--SUMMARY--  
18-Jul-2022  
Decision No. 1642/21  
M.Crystal  
Causation (medical evidence) (standard of proof)  
Evidence (epidemiological)  
Exposure (chemicals)  
Exposure (lead)  
Exposure (polycyclic aromatic hydrocarbons)  
Exposure (radiation)  
Exposure (polyvinyl chloride)  
Initial entitlement (eligibility)  
Cancer (brain) (glioblastoma multiforme)  
The worker, through his estate, sought entitlement to benefits for glioblastoma multiforme (GBM), a type of brain cancer.  
The appeal was denied.  
The Vice-Chair agreed with statements contained in the Demers Report, which noted that all cancers are likely to have  
multiple causes, and that in some cases, there may be synergy between causes and the joint effects can be much  
greater. The Vice-Chair noted that where the evidence does not disclose that it is probable that an occupational  
exposure made a significant contribution to the development of the cancer, and unless there is evidence about a  
particular synergy existing between the occupational exposure and another factor which is present, then it would be  
speculative to allow entitlement on the basis of a synergy between or among factors based on the general proposition  
that all cancers are likely to have multiple causes. The Vice-Chair determined that the medical and epidemiological  
evidence in this case did not indicate a synergistic effect that would support, on a balance of probabilities, that the  
worker's GBM was due to work-related factors.  
In summary, the Vice-Chair concluded that the case materials did not provide information supporting the conclusion that  
the worker's occupational exposures or potential exposures made a significant contribution to the worker's GBM in  
relation to following agents: lead; polyvinyl chloride (PVC/PVMs); Polycyclic Aromatic Hydrocarbons (PAHs) including  
exposures to solvents, combustion products and other process emissions; mercury; arsenic; other environmental agents  
listed in the Advisory Committee Report, such as asbestos, copper, hydrogen cyanide, chromic acid, dicumyl peroxide,  
and other agents; exposures from TIG welding; and, ionizing radiation.  
Furthermore, the estate's representative submitted that the evidence of the rate of incidence of brain cancer at the  
employer's production facility, around the period of the worker's employment there, should be considered. It was his  
submission that the rate of incidence of brain cancer of individuals employed at the facility from 1976 to 2018 greatly  
exceeded the expected rate of the incidence of brain cancer in the general population, and that this provided evidence  
that the worker's occupational exposures, while employed by the accident employer, made a significant contribution to  
his brain cancer.  
From the information presented in the case materials, the Vice-Chair determined that he was unable to give weight to  
the submissions, as they did not appropriately take into account the number of persons to be studied or the duration of  
such a study, which would be necessary to capture the six claims relating to brain cancer arising from the employer's  
facility that were registered with the Board from 1976 to 2018.  
The Vice-Chair noted that where there is a lack of evidence supporting the cause of the cancers, other evidence, such  
as the circumstantial evidence provided by the fact that the cancers occurred at the same employment location and at  
contemporaneous times, might nevertheless provide the basis of a finding that the cancers were occupationally related.  
However, the circumstances in this case differed. The submissions indicated that six brain cancer claims (which may  
have involved different histopathologic types of brain cancer) were registered to the employer's production facility over  
42 years. The employer's production facility in this case encompassed a large physical area, apparently about the size  
of a city block, and included multiple buildings and departments. Many of the buildings presented diverse environments,  
including a nuclear facility in a corner of the area. The employer's facility also employed thousands of workers (the  
actual number was not available), over a period of 42 years. The Vice-Chair determined that this information did not  
provide significant circumstantial evidence to conclude, in the absence of stronger epidemiological or other scientific  
evidence related to causation of the brain cancer, that the worker's occupational exposures at the employer's facility  
made a significant contribution to the development of his GBM.  
Lastly, the worker's claim to the Board was not related to his work as a voluntary firefighter, and it was exclusively  
related to his entitlement arising from his occupational exposures while employed by the accident employer, a company  
in the private sector. The Board had not provided a final decision on the question of whether the worker was entitled to  
benefits in relation to his service as a volunteer firefighter, and the Vice-Chair lacked jurisdiction to address the  
question. Therefore, the worker could not obtain the benefit of the statutory presumption included in the Act in favour of  
firefighters.  
43 Pages  
References: Act Citation  
WSIA  
Other Case Reference  
[w3622s]  
CASES CONSIDERED: British Columbia (Workers’ Compensation Appeal  
Tribunal) v. Fraser Health Authority, 2016 SCC 25, [2016] 1 S.C.R. 587 refd  
to; Fraser Health Authority v. Workers Compensation Appeals Tribunal,  
2013 BCSC 524 distd  
TRIBUNAL DECISIONS CONSIDERED: Decision No. 726/15R, 2021  
ONWSIAT 680 refd to  
Style of Cause:  
Neutral Citation: 2022 ONWSIAT 1111  
WORKPLACE SAFETYAND INSURANCE  
APPEALSTRIBUNAL  
DECISION NO. 1642/21  
BEFORE:  
M. Crystal: Vice-Chair  
HEARING:  
November 3, 2021 at Toronto  
Oral  
Post-hearing activity completed on November 12, 2021  
DATE OF DECISION:  
July 18, 2022  
NEUTRAL CITATION:  
2022 ONWSIAT 1111  
DECISION(S) UNDER APPEAL: WSIB ARO decision dated November 6, 2019  
APPEARANCES:  
For the worker:  
For the employer:  
Interpreter:  
Mr. J. Patterson, Office of the Worker Adviser  
Did not participate  
Not applicable  
Workplace Safety and Insurance  
Appeals Tribunal  
Tribunal d’appel de la sécurité professionnelle  
et de l’assurance contre les accidents du travail  
505 University Avenue 7th Floor  
Toronto ON M5G 2P2  
505, avenue University, 7e étage  
Toronto ON M5G 2P2  
Decision No. 1642/21  
REASONS  
(i) Introduction  
[1]  
[2]  
This appeal was heard in person, on November 3, 2021 at Toronto. The worker, through  
his estate, appeals the decision of Appeals Resolution Officer (ARO) J. Manghoff, dated  
November 6, 2019. That decision determined that the worker, through his estate, is not entitled  
to benefits for glioblastoma multiforme (GBM), a type of brain cancer.  
The worker passed away on September 4, 2012. His estate was represented by Mr. Jason  
Patterson, Office of the Worker Adviser. The worker’s widow, as well as one of the worker’s  
former co-workers, Mr. D., testified at the appeal hearing. Oral submissions were provided at  
the hearing by Mr. Patterson.  
(ii) Synopsis  
[3]  
In the circumstances of this appeal, the worker was employed by the accident employer,  
the operator of a facility that manufactured electrical and related products, including large and  
small electrical motors and related componentry. The facility carried on welding operations, and  
also produced wire, rubber and plastic for wire installation. The facility was a complex, which  
included multiple different buildings where operations were carried on. The worker was  
employed in several different departments at the complex between 1965, when he was 16 years  
old, and 2007, when he retired from this employment. Although the materials did not include  
precise information about the number of employees who worked at the complex from time to  
time, information included in submissions provided by the worker’s representative indicated that  
at the height of production at the complex in the late 1990s and early 2000s, more than 6,000  
individuals were employed at the complex.  
(a) The Board’s Occupational Hygiene Exposure Assessments  
[4]  
[5]  
The Board carried out three occupational hygiene (OH) exposure assessments, which  
sought to provide detailed information about the worker’s occupational exposures while he was  
employed at the employer’s complex. The initial OH exposure assessment report, dated  
September 17, 2012, was prepared by Derrick Chung, occupational hygienist. This report  
provided information about the worker’s work history from 1965 to 2007.  
The report stated that the worker was employed at the accident employer’s complex for  
42 years, performing a variety of jobs in the “Armature” (an area of the complex which  
manufactured various sizes of coils for generators, motors and subcomponents), the wire and  
cable department, and in the Formex building, where wire and cable were processed. The report  
provided the following history of the worker’s jobs at the complex.  
From 1965 to 1970 the worker performed various jobs, including punch press  
operator and manufacturing small motors;  
From 1970 to 1984, the worker worked as a Formex machine operator;  
From 1984 to 1989, the worker performed brazing and assembly work;  
From 1989 to 1995, the worker performed the job of “wind, wedge and connect” in  
the armature department;  
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Decision No. 1642/21  
From 1995 to 2007, the worker performed the job of “wind, wedge and connect” on  
a different floor in the Armature building.  
[6]  
The 2012 OH exposure assessment report also provided the following information  
concerning the worker’s overall work history:  
Details of the worker's [accident employer] employment history from 1965 to 2007 were  
provided by the employer. During this period he was primarily employed in the armature  
years) and Formex… (13.6 years), buildings #7 and #24, respectively. In addition to these work areas the  
worker spent short periods of time in punch press (2 .6 yr.), index press (1.25 yr.), small motors (2.67 yr.),  
wire and cable: [building #22] (4.75 yr.)…  
[7]  
The report indicated that during the period from 1965 until 1995, the worker had  
potential exposure to process emissions, organic solvents, and combustion products.  
[8]  
In relation to “process emissions”, the report stated that “the lower level of Armature  
contained a variety of processes, including the VPI tanks, epoxy cure ovens, metal coating, silver  
brazing and mild steel welding (a variety of metal fumes including cadmium, lead, and copper).”  
[9]  
In relation to “organic solvents”, the report stated:  
A variety of cleaning solvents were used, including “l500 Thinners” (toluene), methyl  
ethyl ketone, acetone, mineral spirits and possibly trichloroethylene as a degreaser. Other  
organic vapours could have included vinyl toluene and epoxy resins. Information from  
Lal (2006) noted that MSDS information indicated the epoxy adhesive (L-62 77 A)  
contained diglycidyl ether /bisphenol A epoxy (60 100%) and butyl glycidyl ether (10  
30%); decomposition byproducts include aldehydes, ketones, chlorinated hydrocarbons.  
Epoxy hardener might have included L-5142 B contained triethylenetetramine (l00%).  
[10]  
The report stated in relation to “combustion products”, that “a variety of lubricating oils,  
coatings and cleaning solvents came into contact with the heating elements of the coil presses.  
This probably resulted in some combustion by-products, such as aldehydes, nitrogen oxides,  
carbon monoxide and carbon dioxide.”  
[11]  
[12]  
In relation to “particulates and fibres”, the report stated that “several types of insulating  
tapes were used including mica, fiberglass, epoxy-coated and asbestos.”  
The report provided the following information under the heading “Exposure  
Assessment”:  
A review of available references and the claim file suggested that the assessment should  
consider the worker's potential exposure to epoxy resins; in addition, the assessment  
included other process emissions. The assessment was based on available information  
collected from the employer, OHCOW [Occupational Health Clinics for Ontario  
Workers], and Ministry of Labour.  
Epoxy Resin: The worker's exposure to epoxy resins possibly occurred during his  
approximately 17.5-year tenure in the Armature building. This work area [was] involved  
with the manufacture of copper coils and other electrical components. The available  
process information suggested that epoxy resins were applied as a coating onto the coils.  
This suggests that the worker was potentially exposed on a routine basis to epoxy resins,  
via airborne vapours and possibly via dermal contact.  
Process Emissions: The worker was primarily located in process buildings #22, #24 and  
#7 during 42-year career with [the accident employer]. Available process information  
suggested that workers in these buildings were potentially exposed [to] a number airborne  
contaminants. During his tenure in building #22 the worker was primarily involved with a  
brazing process. This work process potentially exposed the worker to metal fumes that  
Page: 3  
Decision No. 1642/21  
possibly included cadmium, lead and copper. No information was available to suggest  
that the worker was routinely located near the rubber or PVC handling areas during his  
tenure in building #22.  
While in building #24 the worker operated machines that applied varnish coatings onto  
copper cables for about 13.5 years. The composition of these coating were not available.  
Information [from] OHCOW… indicated that the Formex process involved the use of  
several organic solvents, including MEK and toluene.  
The worker was located on the lower floor of Armature (building #7) for a total of 5.75  
years. While in this area the worker was potentially exposed to emissions from the VPI  
process tanks. These large vacuum-pressure tanks impregnate the coils assembly with a  
resin. As suggested [above in the report], coils were coated with polyester or epoxy resin;  
the polyester resin containing vinyl toluene. In addition to organic solvents emissions  
from coil coatings, workers in the area were potentially exposed to combustion by-  
products from various heated processes such as welding, various ovens and furnaces.  
The worker's available employment history did not suggest that he worked in the nuclear  
products building. Information from the [accident employer’s] Health Study…indicated  
exposures to arsenic were limited to buildings 16A and 10A. The available work history  
information did not suggest that the worker was located in these buildings.  
[13]  
In 2014, the Board received information indicating that the worker had performed TIG  
(Tungsten Inert Gas) welding in his employment with the accident employer. According to a  
Board “OH referral” memo, dated November 18, 2014, the worker’s family had requested  
clarification on the worker’s job activity and had specifically requested clarification on whether  
he performed TIG welding. The memo stated that “the employer has confirmed that [the worker]  
did TIG welding on rotors on [a] daily basis.” The memo noted that this question had not been  
addressed in the initial OH Exposure Assessment report, and that a further OH assessment was  
initiated by the Board.  
[14]  
Mr. Chung prepared a further “Occupational Hygiene Review”, dated February 3, 2015,  
in relation to the issue of the worker’s exposures related to TIG welding. Under the heading  
“Summary”, the report stated:  
A review of the available process and work history information suggests that the worker  
was potentially exposed to radiation while performing TIG welding. The available  
information suggests that under normal conditions the worker's potential exposure to  
radiation was likely below occupational guidelines.  
[15]  
The report went on to provide the following information about the process of TIG  
welding. In this regard, the report stated:  
Information from an industry publication indicated that Tungsten Inert Gas Welding, also  
known by its acronym as TIG welding, is a welding process that uses the heat produced  
by an electric arc created between non-consumable tungsten electrode and the weld pool.  
This electric arc is produced by the passage of current through a conductive ionized inert  
gas that also provides shielding of the electrode, molten weld pool and solidifying weld  
metal from contamination by the atmosphere. The process may be used with or without  
the addition of filler metal using metal rods.  
Burgess (1981) noted that the metal fumes from TIG welding can originate from the base  
metal, filler metal and electrode. Other hazards include gases and vapours, including  
ozone and nitrogen dioxide. The use of an electric arc suggests the potential for  
electromagneticradiation.  
[16]  
The report went on to provide exposure values for full time TIG welders, noting that “the  
available information did not suggest that the worker was a full-time welder; as such his  
Page: 4  
Decision No. 1642/21  
exposure to ionizing radiation was likely less than the levels reported above” for a full-time TIG  
welder. The report also indicated that “arc welders are potentially exposed to magnetic  
radiation.” Under the heading, “Comments & Conclusions”, the report stated:  
The assessment focused on the worker's potential exposures while performing TIG  
welding. These exposures included metal fumes, most likely from the base metal and  
filler rod. TIG welding involves an electrical arc; as such workers performing this work  
are potentially exposed to radiation. The literature suggests that under normal operating  
conditions exposures to ionizing radiation and magnetic fields are likely to be below  
occupational guidelines.  
[17]  
The case materials included a document entitled “The Report of the Advisory Committee  
on Retrospective Exposure Profiling of the Production Processes at the [name of accident  
employer] Production Facility in [name of city] 1945 – 2000.” The report, dated  
February 5, 2017, was prepared by Robert DeMatteo B.A., M.A., D.O.H.S. and Dale DeMatteo,  
B.A., M.Sc., together with eleven individuals who were “Retiree Members of the Advisory  
Committee” (i.e., individuals who had retired from employment with the accident employer at  
the production facility). The document included an “Introduction”, which began with the  
following paragraphs:  
The purpose of this research project was to develop retrospective exposure profiles of the  
work processes at the [accident employer] electrical productions facility in [name of city]  
between 1945 and 2000. As such, it involved a systematic effort to collect and analyze  
empirical information about how production was carried out in this very complex heavy  
industrial operation. Historically, this workplace is an example of the intersection of 20th  
century industrial and chemical “revolutions”. This work was undertaken to document  
the extent and nature of chemical and physical exposures that are possibly linked with the  
various cancers and other diseases that many [accident employer] employees and their  
families suffered over the years.  
The major source of this information came from the workers themselves through a series  
of intensive focus group and key informant interviews that went on for over 8 months.  
This information was corroborated by government inspection reports from 1945 to 2000  
in addition to joint health and safety committee minutes, internal memoranda, and  
industrial hygiene literature.  
[18]  
In an operating level decision, dated November 27, 2015, the Board denied entitlement to  
benefits for the worker’s GBM. The worker’s representative at the time requested a  
reconsideration of the decision, and upon the publication of the Report of the Advisory  
Committee, the Board referred the case for a further OH assessment. The materials included an  
OH Referral memo, which stated that “new exposure information contained in Advisory  
Committee Report is noted” and that Board was seeking an OH opinion on the question, “Does  
information presented in the Advisory Committee report alter the assessment of the worker’s  
exposure to radiation?”  
[19]  
Mr. Chung prepared a further “Occupational Hygiene Review”. The document stated  
that “this review will focus on ionizing and non-ionizing radiation using available information  
collected from [the accident employer’s] Health Study and the Advisory Committee Report; and  
where appropriate, information from the published literature.” The document included the  
following information:  
Ionizing radiation: a review of information from [the accident employer’s]  
Health Study noted exposure to ionizing radiation could have occurred in  
Nuclear Products (bldg. 21) during the manufacture of uranium fuel bundles.  
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Decision No. 1642/21  
Similar information was contained in the Advisory Committee Report. In  
addition, the Report noted potential exposure during the operation of x-ray  
machines. These machines were used, by radiographers, to perform non-  
destructive testing of weldments. The Report mentioned worker concerns in the  
following buildings:  
Punch Press (bldg. 12): JHSC [Joint Health and Safety Committee]:  
11/15/82: re: radiation: “Query radiation checks since x-ray room  
beside this work area has been increased. Workers upset this problem  
has persisted for over a year.” pg. 71  
Structural Steel (bldg. 14/14A): “After welding, all tanks were grit  
blasted, x-rayed, cleaned and grinded, horizontally machined,” pg. 82  
[emphasis in original]  
The worker's employment records did not indicate he was located in building 21. None of  
his job titles suggested he performed work as a radiographer or operated non-destructive  
testing equipment; as such, the available records do not suggest the worker was directly  
exposed to known sources of ionizing radiation at the [name of city] site.  
The worker was located in punch press for about 2.6 years, from 1965 to 1970. No  
information was available to describe the worker worker's location in building 12 in  
relation to the x-ray room.  
Non-ionizing radiation: a review of information from Advisory Committee Report  
noted several locations of potential exposure to electromagnetic fields (EMF), as  
presented below:  
Building 10: "Exposure to Electromagnetic fields during electrical testing  
at very high voltages. Workers were chronically exposed to EMFs at very  
high amperages." pg. 67  
Structural Steel (bldg. 14/14A): ''A great deal of the welding was electric  
arc welding. The welding machines could operate at 600 amperes and  
produced very strong magnetic fields. Welders worked in close proximity to  
these welding units while others nearby worked in by-stander positions to  
these fields." pg. 85  
Switchgear (bldg. 16): ''Aluminum Welding in Bay 319 used very high  
amperages exposing workers to very high EMFs." pg. 92  
Transportation/Diesel Equipment (bldg. 16A): The process of rebuilding of  
diesel motors involved testing the reassembled motors. "Testing went on  
throughout the remanufacturing process to ensure product met performance  
standards for quality control. Motors were run with high voltages called  
heat runs. This produced high EMFs and Ozone gas." pg.100 [emphasis in  
original]  
The Advisory Committee Report contained a number of supporting documents pertaining  
to radiation, including reports from the MOL and the JHSC. A review of this supporting  
information noted: the use of radium luminous paints in a December 23, 1955 memo, a  
March 23, 1983 health and safety committee report noting a microwave oven requiring  
maintenance, and a November 9, 1987 MOL report that described the RF electromagnetic  
fields from the induction brazing units used to weld fuel bundles, presumably in building  
21.  
The worker's employment records did not suggest he was located in work areas noted  
above. Further, none of his job titles suggested he performed high amperage testing of  
motors or generators. As noted above, a portion of the worker's duties involved TIG  
welding. His nonionizing exposure from this source was described in the 2015 EA Report  
on file.  
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Decision No. 1642/21  
(b) Testimony at the appeal hearing  
[20]  
[21]  
The worker’s widow, Mrs. C., testified at the hearing for this appeal that was held on  
November 3, 2021. She testified that she married the worker in 1967, and that she was married  
to him until his death in September 2012, just prior to their 45th wedding anniversary. She noted  
that the worker had already been employed by the accident employer for about one and a half  
years when they met.  
Mrs. C. testified that the worker had never been a smoker. She stated that he ate a  
healthy diet, which included meat and plenty of fruits and vegetables. She testified that the  
worker brought his lunch to work every day, and that he typically ate his lunch and had coffee at  
his work station. She also testified that, outside of work, the worker had been an active person  
during their marriage, and that he participated in walking, cycling, and sports including baseball,  
skating and hockey. She testified that the worker had never experienced a concussion or any  
other type of head injury.  
[22]  
Mrs. C. testified that, at the start of the worker’s employment with the accident employer,  
the worker worked in the punch press, wire and cable, fractional motors and armature  
departments. As will be discussed below, the employer had a routine of shutting down certain  
areas of the complex during a few weeks of the year for heavy industrial cleaning and  
replacement of some equipment. Mrs. C. testified that the worker performed cleaning work  
during the shutdowns.  
[23]  
Mrs. C. also testified that the worker smelled of different odours, depending upon in  
which department he had been working. She stated that after working in the armature  
department, she detected a sweet smell. She also noted that when the worker returned home  
from working in the punch press or wire and cable departments, he had an unpleasant odour, and  
the worker took off his boots and clothes in an outside shed, before entering their home. She  
stated that the worker would have a shower after removing his clothes, but that the smells from  
the employer’s workplace lingered on him. She stated that she did the worker’s laundry and that  
his work clothes smelled bad.  
[24]  
Mrs. C. also testified that the worker frequently had cuts on his hands, many of them  
deep, particularly on his thumbs, and that while working, he frequently had band-aids on his  
hands. She stated that when the worker was on vacation from work, his hands would heal up.  
She also noted that the worker had lesions on his face and hands, which were dry and flaky, and  
that he applied cream to his face and hands a few times per day. She stated that when she asked  
the worker about these lesions, he did not provide a clear answer, but stated that he believed that  
the problem was caused by “chemicals at work”. Mrs. C. also described “hot spots” that the  
worker had on his head, and that he would put ice packs on his head while he was watching TV.  
She stated that she learned about the “hot spots” only a few weeks prior to his diagnosis of  
GBM/brain cancer.  
[25]  
Mrs. C. stated that the worker also experienced nosebleeds while he was working in the  
armature department, and that it was her estimate that the nosebleeds occurred about once per  
week when he was working in that department.  
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Decision No. 1642/21  
[26]  
Mrs. C. testified that by the time of the worker’s first seizure, which led to his diagnosis  
of GBM/brain cancer, the worker had retired from his employment with the accident employer.  
She stated that he retired in 2007, when he was 58 years old, because he was not feeling well and  
because “he was exhausted”. She stated that she believed that had he not felt unwell, he would  
have worked for three or four more years, and retired at age 62. She stated that after the worker  
had been diagnosed with GBM/brain cancer, he stated that he believed that the cancer had been  
caused by his chemical exposures at the accident employer’s workplace. She also testified that it  
was her view that the worker’s cancer was caused by his exposure to toxins at the employer’s  
workplace.  
[27]  
Mr. D., who was a co-worker of the worker at the employer’s workplace also testified at  
the appeal hearing. Mr. D. testified that he worked for the accident employer for over 33 years,  
and that he worked in a variety of departments at the employer’s workplace. He stated that two  
functions he performed for a significant time was operating a hitch driving crane, and operating  
the “VPI tanks” which were used in the armature department. He later explained in his  
testimony that a VPI tank was used to a submerge a wound rotor to be used in a motor. He  
explained that a wound core had to be dipped in a tank which contained a type of “varnish” or  
resin to consolidate the rotor. He stated that in the armature department the wound item would  
be dipped in the varnish, squeegeed, baked and then grinded, and that the process of “dip, bake,  
grind” would be repeated three times as part of the armature production process. Mr. D. stated  
that he was not certain about the composition of the chemicals in the VPI tanks because the  
composition changed frequently.  
[28]  
[29]  
Mr. D., who stated that he was 70 years old at the time of the appeal hearing, testified that  
he was hired in 1974, at about age 23, and that he was a co-worker with the worker for about  
15 years in the employer’s armature department. He stated that he also worked with the worker  
in other departments, where he assisted the worker as a crane operator.  
Mr. D testified that shutdowns of the employer’s production facility occurred on a regular  
basis, once per year. He noted that the duration of the shutdowns was typically about three  
weeks, although the length of the shutdown could be different from area to area. Mr. D. stated  
that he worked on shutdowns, and that involved draining tanks, cleaning sludge and cleaning up  
cuttings. Mr. D. stated that he was not certain about the extent that the worker worked on  
shutdowns, because they worked in different departments. He stated that he did not think that  
the worker worked too much on shutdowns, but that the worker would likely have had to work  
on some shutdowns, particularly early in his career, given that this work was generally  
performed by workers with low seniority. Mr. D. stated that he was aware that during shutdown,  
workers would typically be exposed to coolant, and that workers performing shutdown cleaning  
could be exposed to other chemicals, including acids.  
[30]  
Mr. D. also testified that ventilation was generally poor at the employer’s production  
facility. He noted that the facility was comprised of a large building that was divided into  
smaller departments, which were also referred to as buildings, and smaller separate buildings  
located to the north of the large building. He noted that in the large building, there were not  
always doors between the departments and areas, and that, where there were doors, the doors  
frequently remained open. He noted that the large building had large doors at one end, and that  
in good weather, these doors remained open and ventilation was better. He noted, however, that  
in colder weather, the doors were closed and ventilation was poor. He noted that when he started  
his employment, no exhaust fans were in use. He also noted that welding was performed in the  
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Decision No. 1642/21  
armature department, but that exhaust hoods were not used. Mr. D. stated that the status of the  
ventilation at the plant did not improve significantly during his period of employment with the  
accident employer. Mr. D. noted later in his testimony that chemical fumes, from products like  
trichloroethylene, could migrate throughout the large building.  
[31]  
Mr. D. was questioned about the use of personal protective equipment (PPE) by the  
worker. He stated that where workers worked inside a VPI tank, they were provided with simple  
filtering masks which were not fit-tested, and that he was not aware of any cartridge type  
respirators being used at the plant. He noted that he and the worker typically wore jeans and a T-  
shirt to work and that they typically did not have PPE available to them, with the exception of  
occasional use of filtering masks or cotton gloves.  
[32]  
Mr. D. testified about fires, particularly in the armature department where the worker was  
employed from about 1989 to 2007. He noted that, in 1972, a VPI tank “blew up” and caused a  
significant fire, but that small fires, which workers would put out themselves with rags and a fire  
extinguisher, might occur once per month. He noted that fires could arise from TIG and MIG  
welding, if the welding coil flared and that ovens might also flare up when they became  
overheated. He noted that the plant had a sprinkler system which was not working.  
[33]  
[34]  
Mr. D. also testified that he was aware that the worker performed TIG welding while  
employed by the employer. He stated that the worker used a welding shield but that he did not  
use much other PPE when welding. He stated that welding work was remunerated on a piece  
work basis and that workers were paid more if they could complete welds more quickly.  
Mr. D. also testified that he was aware that the worker had worked as a volunteer  
firefighter during about 14 years from 1978 to 1992. He stated that he believed that the worker  
probably typically attended at about one fire per month as a volunteer firefighter, but that he did  
not believe that the worker would have been exposed to radiation or electromagnetic fields as a  
volunteer firefighter.  
(c) Medical evidence  
[35]  
The case materials included a “Cardiology/ICU Admission Note”, dated March 24, 2012,  
prepared by Dr. Warren Ball, cardiologist, which provided a history of the worker’s condition  
and progress. The report stated that the worker had been admitted to hospital with a decreased  
level of consciousness which had not yet been diagnosed. It stated that, during the month of  
February 2012, the worker was on vacation outside of Ontario, when his family indicated that he  
reported feeling unwell, becoming easily agitated and impatient, which was unlike him. The  
worker also reported severe night sweats, although no fever or chills. The report indicated that,  
in mid-March 2012, he was eating at a coffee shop with friends, when he collapsed and there was  
a suggestion that he may have experienced tonic clonic seizures for a few minutes. The worker  
was subsequently discharged from hospital, although a few days later, he exhibited some unusual  
behaviour at home, and collapsed again, and again returned to hospital.  
[36]  
The worker underwent an MRI of the brain on March 27, 2012, which disclosed that the  
worker had a “4 cm mass in the left temporal lobe as described most likely related to a primary  
CNS [central nervous system] tumor as opposed to metastasis given the appearance”, and a  
referral to a neurosurgeon was made. On April 4, 2012, brain tissue was surgically obtained for  
biopsy. The biopsy was performed on April 4, 2012, and the report on the biopsy stated that  
“permanent sections show characteristic features of glioblastoma multiforme [GBM].”  
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Decision No. 1642/21  
According to a further report, dated April 30, 2012, prepared by Dr. John Beamish, specialist in  
family medicine and carrying on a practice in palliative care, the worker understood that “his  
disease is incurable”, that “he has discussed his options thoroughly with his family and does not  
want to pursue chemotherapy or radiation therapy”, and that “his preference is to spend this time  
when he is feeling well with his family and not be travelling for therapy.” Dr. Beamish noted  
that “given his diagnosis, this is not an unreasonable decision.” As noted above, the worker  
passed away on September 4, 2012.  
[37]  
[38]  
[39]  
The worker’s case was subsequently referred to Dr. Noel Kerin, a physician with  
Occupational Health Clinics for Ontario Workers (OHCOW). Dr. Kerin is not accredited in any  
area of medical specialization. The worker had previously consulted with Dr. Kerin about a  
claim at the Board for occupational asthma. The case materials included a report, dated  
November 28, 2008, which concerned the worker’s claim for occupational asthma. The worker’s  
claim for occupational asthma was allowed by the Board in November 2015, following the  
worker’s death.  
Dr. Kerin prepared an Addendum Report, dated May 7, 2012, which indicated that the  
worker had been diagnosed with GBM, and which provided information about his condition and  
Dr. Kerin’s views concerning the relationship between his condition and the worker’s  
occupational exposures, referred to further below. Dr. Kerin also prepared a Health  
Professional’s Report (Form 8), which was undated but appears to have been prepared on or  
about May 7, 2012. The Form 8 indicated a diagnosis of glioblastoma multiforme (GBM), and  
referred the reader back to the report for further information.  
Dr. Kerin’s report, dated May 7, 2012 noted that “of particular note was the intensity of  
exposures to various chemicals including asbestos and quartz silica in the Wire & Cable  
Department for approximately 16 years.” After setting out the worker’s work history, which is  
noted above, the report went on to provide the following information under the heading  
“Opinion”:  
Causation of Malignant Tumours:  
The worldwide incidence of primary malignant brain and central nervous system tumours  
is higher in the developed countries (males 5.9 per 100,000 person years). Glioblastomas  
(GBMs) are the second most frequently reported histology and the most common  
malignancy. They account for 16% of all primary brain tumors (Central Brain Tumor  
Registry of the United States 2004-8).  
The levels of industrial dust/chemical exposure in [the worker’s] case is typical in that  
there was no industrial hygiene data available on chemical exposures during much of his  
employment time at [the accident employer]. Review of the literature with respect to  
causation of brain cancers suggests that there are several toxins capable of increasing the  
risk of developing malignant changes such as GBM, e.g.:  
Lead  
Vinyl chloride  
PAHs  
Ionizing radiation  
Solvents/Benzene  
Arsenic  
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Decision No. 1642/21  
Lead  
Edwin van Wijngaarden and Mustafa Dosemeci Int. J. Cancer: 119, 1136-1144 (2006),  
evaluated the association between potential occupational lead exposure and the risk of  
brain cancer mortality in the National Longitudinal Mortality Study (NLMS), which is a  
prospective census-based cohort study of mortality among the noninstitutionalized United  
States population (1979-1989). The present study was limited to individuals for whom  
occupation and industry were available (317,968). Estimates of probability and intensity  
of lead exposure were assigned using a job-exposure matrix (JEM). Risk estimates for the  
impact of lead on brain cancer mortality were computed using standardized mortality  
ratio (SMR) and proportional hazards and Poisson regression techniques, adjusting for  
the effects of age, gender and several other covariates. Brain cancer mortality rates were  
greater among individuals in jobs potentially involving lead exposure as compared to  
those unexposed (age- and gender-adjusted hazard ratio (HR) 5 1.5; 95% confidence  
interval (CI) 5 0.9-2.3) with indications of an exposure -response trend (probability: low  
HR 5 0.7 (95% CI 5 0.2-2.2), medium HR 5 1.4 (95% CI 5 0.8-2.5), high HR 5 2.2 (95%  
CI 5 1.2-4.0); intensity: low HR 5 1.2 (95% CI 5 0.7-2.1 ), medium/high HR 5 1.9 (95%  
CI 5 1.0-3.4)). Brain cancer risk was greatest among individuals with the highest levels of  
probability and intensity (HR 5 2.3; 95% Cl 5 1.3-4.2). These findings provide further  
support for an association between occupational lead exposure and brain cancer  
mortality, but need to be interpreted cautiously due to the consideration of brain cancer as  
one disease entity and the absence of biological measures of lead exposure.  
Poly vinyl chloride (PVC)/vinyl chloride (VMC) [sic – VCM?]  
Vinyl chloride is the organochloride with the formula H2C:CHCl. It is also called vinyl  
chloride monomer (VCM) or chloroethene. At room temperature vinyl chloride is a gas  
with a sickly sweet odor. It is highly toxic, flammable and carcinogenic. Classified as a  
human carcinogen by ACGIH, IARC, OSHA, EPA and European Union, polyvinyl  
chloride is a polymer of VMC [sic] and can off gas VMC [sic] when disturbed or heated.  
USA Environmental Protection Association's (EPA) 2001 updated Toxicological Profile  
and Summary Health Assessment for VCM (EPA, Toxicological Review of Vinyl  
Chloride, Support of Information on the IRIS. May 2000) in its Integrated Risk  
Information System (IRIS) database concludes that “because of the consistent evidence  
for liver cancer (angiosarcoma) in all the studies ... and the weaker association for other  
sites, it is concluded that the liver is the most sensitive site, and protection against liver  
cancer will protect against possible cancer induction in other tissues.” The International  
Agency for Research on Cancer (IARC 1979, 1987) suggesting that vinyl chloride is a  
multisite carcinogen in humans and experimental animals.  
Coating of electric wire manufacturing in the Formex area of the Wire and cable in [the  
accident employer] was manufactured using PVC [and] made extensive use of PVC  
covering. PVC itself is said to be ‘safe’, however, when heated its off-gassing/outgassing  
of contaminants/breakdown products or additives and breakdown products e.g. VMC,  
dioxins and phthalates or plastic softeners are considered to be the principle health risks  
in the heating of PVC. VCM is considered a likely carcinogenic agent in the development  
of brain cancer. As part of the wire coverings in the Wire & Cable Department, [the  
worker] would also have been exposed to polyvinyl chloride degradation as it was heated  
in ovens. He would have also been exposed to the off gassing of vinyl chloride which is  
considered to be a risk factor in developing brain cancer.  
Polycyclic Aromatic Hydrocarbons (PAHs)  
GBM malignant changes trend is found in occupational exposure to solvents and  
petroleum products. It is unknown if [the worker] was exposed to ionizing radiation as  
industrial radiography practices were common in [the accident employer] to x-ray for  
proper quality welding of joints. Ionizing radiation is known to be a risk factor for brain  
cancer. It is clear from coworker histories that x-rays were taken on the shop floor, at  
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Decision No. 1642/21  
times without proper radiation protection for bystander workers. Exposure to arsenic;  
arsenic was commonly used in manufacturing of epoxies at [the accident employer]. It is  
unclear how much exposure [the worker] may have experienced secondary to arsenic  
exposure in epoxies – he did work closely with epoxies.  
Therefore, in the absence of familial tendency to developing brain tumours, the risks of  
prolonged exposure to a chemical factory (Formex area of Wire & Cable Division of [the  
accident employer]) including other exposures, such as those enumerated above, were  
known to be routinely present in the Formex area. [The worker] makes reference to  
mercury being used in a bath where wire coating was checked for integrity of insulation.  
This practice often gave rise to mercury spillage, which would have been apparent on the  
floor of the Formex area on a regular basis.  
When one compares [the worker’s] prolonged daily exposure to a highly chemicalized  
environment, including incomplete products of combustion, other known neurotoxic and  
probably brain carcinogenic agents, it is reasonable to compare [the worker’s] exposures  
to those of a firefighter. In the case of firefighters, brain cancer is considered to be an  
occupational disease when certain minimum exposure criteria are met. In comparison to  
firefighters, [the worker] would have met or exceeded all of the minimum requirements;  
therefore, from an occupational medicine point of view, it is not unreasonable to compare  
his chemical exposures to those workers (firefighters) who are covered under  
presumptive legislation with respect to the occupational origin of brain tumours in  
firefighters.  
A form 8 will be submitted on [the worker’s] behalf claiming an occupational-basis for  
his brain cancer.  
[40]  
Following the receipt of Dr. Kerin’s report, dated May 7, 2012, the Board’s Occupational  
Disease Adjudicator requested a referral to a occupational disease physician for a file review.  
The memo requesting the review provided an “Exposure History”, in relation to which, from the  
wording of the memo, the worker appears to have provided at least some of the information.  
This portion of the memo stated:  
Exposure History: The worker said he worked in the punch press area 1965 to 1967 and  
the environment was very dusty. They didn't have proper ventilation to remove smoke,  
and the location where he worked when he was on the Punch Press machine, was beside  
the oven that insulated steel. When he worked in the Formex building (moved there in  
1970) the worker said the area lacked proper ventilation and when there were fires (which  
were frequent), the smoke and fumes of the varnish drippings off the sheaves would be  
inhaled. If there was a break out on the test pod on the machine was full of mercury, it  
could easily land in your mouth and you would ingest mercury.  
In 1977 he moved to Wire and Cable. Here they produced various types of wires and it  
had a glass covering over it. When there were fires it would emit overwhelming toxic  
fumes that were then inhaled. The worker said they had no breathing apparatus or proper  
ventilation at that time. The worker said he always saw the fibres in the air and he would  
inhale them throughout his shift. Ever since working in the Wire and Cable area, he had a  
constant smell like he had been a heavy smoker and it smelled like burnt pipes. He then  
worked in Armature from 1989 until he retired. He said here dangerous type of brazing  
was done on large bars used for generators. One of the materials used for brazing was  
cadmium. They used K-Wool for cooling down the material and cleaning coils consisted  
of dipping in acetone and the fumes were caustic.  
The worker said he was exposed to the following cancer causing exposures at [the  
accident employer]: vinyl chloride, PAHs, blue smoke, lead, ionizing radiation (x-ray  
with welding) and benzene and solvents. However the worker advised OHCOW that the  
worker was potentially exposed to the following agents aluminum chloride; asbestos;  
benzene; cadmium; chromium; copper; cutting oils or mists; cyanide; DDT; ethylene  
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Decision No. 1642/21  
oxide; epoxy; fibreglass; formaldehyde; MEK; MOCA; naphtha; nickel; nitrogen oxide;  
PCBs; phenols; pipe dope; PVC; silica; styrene; talc; tetra ethyl lead; toluene;  
trichloroethylene; varsol; vinyl chloride; welding fumes; xylene; zinc and polyvinyl.  
[41]  
The memo went on to outline the exposures identified by Dr. Kerin in his report dated  
May 7, 2012 and the exposures identified in the OH Assessment Report, dated  
September 17, 2012, prepared by Mr. Chung, both referenced above. It requested answers to the  
following two questions that the adjudicator wished to pose to the physician undertaking the file  
review:  
1) Could the exposures, as outlined in the occupational hygiene assessment, have  
significantly contributed to the brain cancer?  
2) If not, is there any supporting evidence that the agents cited by OHCOW and the  
worker (which were not confirmed in the occupational hygiene assessment),  
could have resulted in the type of cancer the worker had, whether alone or as a  
combined effect?  
[42]  
The referral to an occupational disease physician was made to Dr. Sean Somerville,  
specialist in Occupational Medicine. Dr. Somerville prepared a memo, dated January 17, 2013,  
setting out his analysis in relation to the questions asked by the Tribunal. The body of the memo  
stated (footnotes have not been included):  
PertinentMedicalInformation/Considerations:  
[The worker] was a long time employee of [the accident employer]. He worked there  
from September 1965 until November 2007. [The worker] was diagnosed with brain  
cancer, namely glioblastoma multiforme, in 2012, which he attributes to workplace  
exposures. He did not have a family history of brain cancer. WSIB Occupational Hygiene  
Exposure Assessment report notes [the worker] potentially exposed to epoxy resin,  
organic solvents, and combustion by-products, including from welding. Apparently, [the  
worker] did not wear personal protective equipment until a few years before his  
retirement.  
….  
Conclusions/Opinion/Response to Question(s):  
Brain tumors are a diverse group of neoplasms arising from different cells of the central  
nervous system. Although brain tumors account for only 2 percent of all cancers, there is  
some evidence that the incidence of these tumors has been increasing for the past fifty  
years. The highest incidence rates are noted in industrialized nations such as the United  
States, Canada, Australia, and the United Kingdom, while developing nations have lower  
rates. Overall survival in patients with malignant brain tumors has not improved  
significantly over the last five decades. However, survival rates vary according to age and  
histologic type. There is a slight male predominance in the incidence of malignant brain  
tumors. Whites have a higher incidence of malignant brain tumors. Gliomas, of which  
glioblastoma multiforme is one type, are primary brain tumors that display histological  
features of glial cells. Glioblastoma multiforme (GBM) rarely occurs before the age of 15  
but dramatically increases after the age of 45.  
Because of their rarity among cancers, the causes and risk factors of brain tumors have  
been difficult to study. Much of the epidemiological research, especially older studies,  
has tended to group all brain tumors together which is problematic since various types of  
tumors appear to have different causes and risk factors. Additionally, the data is often  
inconsistent and limited by small numbers of cases and inadequate or absent exposure  
data. Non-modifiable risk factors for glioblastoma multiforme are male sex, age over 50,  
genetic predisposition and white ethnicity. Some of the proposed modifiable risk factors  
for brain tumors are head trauma, infections, diet, allergies, exposure to electromagnetic  
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Decision No. 1642/21  
fields, oil refinery work, agricultural work, radiation exposure, and exposure to some  
chemicals such as vinyl chloride, petrochemicals and lead. The only firmly established  
modifiable risk factor though is ionizing radiation exposure, especially among children.  
A Medline/PubMed search of "occupational risk factors for glioblastoma multiforme"  
since 1997 resulted in 9 articles, several of which were reviews that concluded the only  
environmental factor unequivocally associated with an increased risk of brain tumors,  
including gliomas, is therapeutic x-rays. Another study of potential risk factors for  
glioblastoma multiforme looked at a cohort of 8006 Japanese-American men, with nine  
histologically confirmed GBM cases. A multivariate Cox proportional hazards model  
demonstrated sugar intake and occupational exposure to carbon tetrachloride were  
independently and significantly associated with development of GBM. The number of  
disease cases is small in this study, and quantification of exposure is lacking. The results  
of this study have not been replicated as yet. Another study was conducted to explore a  
perceived increase in glioblastoma diagnosis at a jet engine manufacturing facility in  
North Haven, Connecticut. Subjects were 212,513 workers ever employed in 1 of 8  
manufacturing facilities from 1952 to 2001 and at risk from 1976 to 2004. 722 cases of  
CNS neoplasms were identified mainly by tracing through 19 state cancer registries.  
Standardized incidence ratios (SIRs) were computed based on state and national rates and  
modeled internal relative risks (RRs). Overall deficits were found in cases for  
glioblastoma (275 cases, SIR = 0.77, Cl = 0.68-0.87) and a not statistically significant  
overall 8% excess in glioblastoma in North Haven (43 cases, SIR = 1.08, Cl = 0.78-1.46).  
No conclusion could be made as to the cause of the excess glioblastoma cases, but non-  
occupational factors and workplace factors unmeasured in the study would need to be  
considered.  
Bhatti and colleagues (4) looked at the possibility that lead exposure was causative in  
GBM formation. Using a hospital-based case-control study, they examined the potential  
carcinogenicity of lead through examination of effect modification of the association  
between occupational exposure and brain tumors by single nucleotide polymorphisms in  
genes with functions related to oxidative stress. Lead exposure was estimated by review  
of detailed job history data for each participant. In analyses restricted to cases with  
glioblastoma multiforme, RAC2 rs2239774 and two highly correlated GPX1  
polymorphisms (rs1050450 and rs18006688) were found to significantly modify the  
association with lead exposure (P < or = 0.05) after adjustment for multiple comparisons.  
The conclusion was that the results of the study showed some evidence that lead may  
cause glioblastoma multiforme and meningioma through mechanisms related to oxidative  
damage, but the results need to be confirmed in other populations. Without occupational  
hygiene data incorporated into the study, the results are hardly verifiable though.  
[The worker] was 65 years old at time of diagnosis of glioblastoma multiforme. The  
WSIB Occupational Hygiene Exposure Assessment indicates he had the potential for  
exposure to epoxy resins on a routine basis for about 17.5 years at work. This exposure  
was via airborne vapors and possibly via dermal contact. [The worker] was also  
potentially exposed to metal fumes that possibly included cadmium, lead and copper.  
Furthermore, exposures were possible to organic solvents and combustion by-products.  
[The worker’s] employment history did not suggest that he worked in the nuclear  
products building, or that he was exposed to arsenic. The OHCOW addendum report of  
May 7, 2012 speculates about a number of exposures, including leading [sic – lead?] ,  
vinyl chloride, polycyclic aromatic hydrocarbons (PAHs), and arsenic.  
Of the four non-modifiable risk factors for glioblastoma multiforme, [the worker] had  
three, namely male sex, age over 50 and ethnicity. He does not have proven workplace  
exposure to ionizing radiation, which is the only known modifiable risk factor for GBM.  
There is no evidence in the medical literature of clear-cut increased risk of glioblastoma  
multiforme from exposure to epoxy resins, metal fumes, organic solvents or combustion  
by-products.  
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Decision No. 1642/21  
Furthermore, there is no increased risk confirmed in the current medical literature for  
exposure to lead, vinyl chloride, PAHs, or arsenic, as suggested by the OHCOW  
addendum report. The one research article included in the OHCOW addendum report  
pertains to lead exposure but does not distinguish between histopathologic types of brain  
cancer. It did not have any biological measures of lead exposure either. Its results do not  
provide evidence of increased risk of GBM from lead exposure. No research studies were  
provided to support increased risk of GBM due to polyvinyl chloride exposure, only  
information regarding increased risk of liver cancer. Once again it is problematic to  
conflate different types of cancer when discussing causation. No medical literature is  
reviewed in the OHCOW addendum report regarding PAHs, arsenic, or other proposed  
exposures. No references are provided regarding the combined effects of various  
exposures and the risk of GBM. The OHCOW addendum report speculates that [the  
worker] may have been exposed to x-rays at work, but there is no evidence to support  
this, or quantification of dose.  
There is no well-established scientific evidence that any of the exposures as outlined in  
the Occupational Hygiene Exposure Assessment report likely significantly contributed to  
the [worker’s] diagnosis of glioblastoma multiforme. The OHCOW addendum report  
suggests a number of other potential exposures. None of them, with the exception of  
ionizing radiation, has been firmly established to increase GBM risk. There is no  
evidence [the worker] was exposed to ionizing radiation.  
Recommendations/Next Steps (if applicable):  
1) The exposures as outlined in the WSIB Occupational Hygiene Exposure  
Assessment report likely did not significantly contribute to the [the worker’s]  
brain cancer (glioblastoma multiforme).  
2) There is no accepted evidence in the current medical literature that the agents  
cited by OHCOW (with the exception of ionizing radiation), either alone or  
combined, could have resulted in the [the worker’s] glioblastoma multiforme.  
There is no evidence [the worker] was exposed to ionizing radiation at work.  
[43]  
As noted above, in 2014, the Board received further information which indicated that the  
worker had performed TIG welding in his employment with the accident employer. As is also  
noted above, upon receipt of this information, the Board requested a further occupational  
hygiene assessment in order to identify the worker’s exposures which were associated with this  
activity. The report on that occupational hygiene assessment, prepared by Mr. Chung, is  
excerpted above. Following the receipt of that report, the Board requested a further occupational  
medicine physician review from Dr. Somerville, in relation to the new occupational hygiene  
assessment prepared in relation to TIG welding. The referral memo requesting the review asked  
the following question:  
Could the exposures outlined in the occupational hygiene assessment dated February 6,  
2015 [i.e., the occupational hygiene assessment made in relation to TIG welding] have  
significantly contributed to the glioblastoma multiforme (GBM)?  
[44]  
The referral memo also included the following information:  
I contacted [the accident employer] and confirmed that the worker did TIG welding on  
rotors on a daily basis. Depending on the products that are being manufactured, he could  
have potentially performed TIG welding but could have also performed MIG or copper  
welding. [The accident employer] was unable to confirm how long he performed TIG  
welding or which specific job he may have performed this task, noting he had performed  
various jobs during his tenure at [the accident employer].  
The original exposure assessment reviewed processes and emissions encompassing the  
areas and buildings where the worker worked. Besides the TIG welding, there was no  
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Decision No. 1642/21  
other information in the binder [i.e., information recently provided by the worker’s  
family] that would change our understanding of the worker's potential exposures.  
Additional Occupational Hygiene Assessment Review  
A further occupational hygiene assessment was carried out to assess the worker's  
potential exposure during TIG welding. The available information indicates the worker  
spent a portion of his shift performing arc welding such as TIG, Metal Inert Gas (MIG) or  
copper welding. The employment information indicates he was not a full time welder.  
Information to characterize the shift duration of his TIG welding duties, or the base  
metals and filler metals that were used was not available. A 2003 study replicated TIG  
welding condition and sampled airborne thorium exposure during welding and grinding  
tasks. The effective dose from inhalation for a full-time TIG welder under realistic work  
conditions was below 0.3 mSv [ i.e., a “millisievert” which is unitized measure of health  
effect of ionizing radiation] and with conservative assumption around 1 mSv or lower.  
His potential exposure to ionizing radiation was likely less than the levels reported since  
he was not a full-time welder.  
In addition arc welders are potentially exposed to magnetic radiation. This exposure can  
be modified by a number of factors, including power source, position and distance of the  
cables relative to the body.  
The occupational hygienist concluded the worker's potential exposures while performing  
TIG welding included metal fumes, most likely from the base and filler rod. TIG welding  
involves an electric arc; as such the worker was potentially exposed to radiation. The  
literature suggests that under normal operating conditions exposures to ionizing radiation  
and magnetic fields are likely to be below occupational guidelines.  
[45]  
In response to the referral, Dr. Somerville provided a further memo, dated June 15, 2015,  
which included the following information:  
PertinentMedicalInformation/Considerations:  
[after a brief summary and reference to Dr. Somerville’s earlier memo]  
…A new Occupational Hygiene Review is now on file dated February 3, 2015. The  
report describes [the worker’s] potential exposures during TIG welding. The review  
indicates the majority of [the worker’s] tenure at [the accident employer] was spent  
performing a variety of jobs in the Armature, wire and cable and Formex buildings. A  
portion of the [the worker’s] duties involved welding, including TIG welding. The  
review provides an exposure assessment and states that a 2003 study reported that for a  
full-time TIG welder under realistic work conditions ionizing radiation exposure was  
below 0.3 mSv and with conservative assumptions around 1 mSv or lower. The  
information on file did not suggest that [the worker] was a full-time welder and as such  
his exposure to ionizing radiation was likely less than these levels. The occupational  
hygiene review concludes that TIG welders are potentially exposed to radiation, however  
the literature suggests that under normal operating conditions exposures to ionizing  
radiation and magnetic fields are likely to be below occupational guidelines.  
Conclusions/Opinion/Response to Question(s):  
The incidence of glioblastoma multiforme is 3.19/100,000 population, with the median  
age at diagnosis being 64 years. As stated in my Initial Case File Review Memo, the  
incidence is higher in men and those of white ethnicity. Many genetic and environmental  
factors have been studied with respect to this cancer, but the majority of cases are  
sporadic, and no risk factor accounting for a large proportion of cases has been identified.  
As mentioned in the previous Case File Review Memo, ionizing radiation has been  
established as a risk factor for glioblastoma multiforme. An association with high-dose  
ionizing radiation and brain tumors has been observed in atomic bomb survivors, nuclear-  
test fallout data, therapeutic radiation for cancer, and occupational and environmental  
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Decision No. 1642/21  
studies, however the evidence is more limited at the level of the specific histologic type  
of tumor, particularly for low to moderate dose settings. In this case, the occupational  
hygiene review stated that for a full-time TIG welder under realistic work conditions  
ionizing radiation exposure was below 0.3 mSv and with conservative assumptions  
around 1 mSv or lower. [The worker] was not a full-time TIG welder, and so his likely  
exposure was even lower. According to Health Canada, the amount of natural  
background radiation individuals receive each year in Canada is between 2 and 4 mSv,  
and the Canadian Nuclear Safety Commission sets a limit of 50 mSv in a single year and  
100 mSv over five years (a 20 mSv per year average). A consensus of radiation experts  
has concluded that the lowest acute dose of X or gamma radiation for which there is good  
evidence of increased cancer risk is approximately 10 to 50 mSv. The current evidence  
on file suggests [the worker’s] potential exposure to ionizing radiation was very modest,  
and the scientific literature does not clearly support increased risk of glioblastoma  
multiforme from such low-level ionizing radiation exposure. Furthermore a Medline  
search for welding and glioblastoma multiforme did not result in any studies.  
A possible association between occupational exposure to extremely low frequency  
magnetic fields and brain tumors has been examined in a number of studies, with mixed  
results, however the International Agency for Research on Cancer (IARC) concluded in  
2002 that the evidence was inadequate to classify extremely low frequency magnetic  
fields as a carcinogen for brain tumors.  
In my opinion there is insufficient medical and scientific evidence the exposures outlined  
in the Occupational Hygiene Assessment dated February 3, 2015 significantly  
contributed to [the worker’s] glioblastoma multiforme.  
[46]  
[47]  
[48]  
As noted above, the case materials included a document entitled “The Report of the  
Advisory Committee on Retrospective Exposure Profiling of the Production Processes at the  
[name of accident employer] Production Facility in [name of city] 1945 – 2000”, dated  
February 5, 2017, prepared by Robert DeMatteo B.A., M.A., D.O.H.S. and Dale DeMatteo,  
B.A., M.Sc., together with eleven individuals who were “Retiree Members of the Advisory  
Committee”. According to an Occupational Hygiene Referral memo, dated December 14, 2017,  
a further occupational hygiene assessment was requested, in order to review “new exposure  
information contained in the Advisory Committee Report.” The referral memo requested an  
opinion on the question:  
Does information presented in the Advisory Committee report alter the assessment of  
worker’s exposure to radiation?  
Mr. Chung prepared a third “Occupational Hygiene Review” document, dated  
December 28, 2017, which is excerpted above. After receiving this additional occupational  
hygiene review, the Board requested a further Medical Consultant file review. The requesting  
memo stated that the referral question to the occupational medicine consultant was:  
There has been a request for reconsideration of the initial entitlement decision for this  
claim for brain cancer. Documents submitted to WSIB by [the worker’s union] and the  
Advisory Committee Report for [accident employer] Production Facility, [name of city]  
2017, mentions ionizing and non-ionizing radiation. The supporting documents include  
reports from the Ministry of Labour and the Joint Health & Safety Committee. Please  
note the Industrial Hygiene review on file dated December 28, 2017 with respect to  
radiation. Please provide an opinion on the occupational relatedness of this worker’s  
brain cancer.  
Dr. Somerville provided a further memo, dated January 18, 2018, to the Board, in  
response to this further referral from the Board. The background information included in  
Dr. Somerville’s report included much of the same information that was included in his earlier  
Page: 17  
Decision No. 1642/21  
memos, and also included some of the information included in Mr. Chung’s occupational  
hygiene assessment. Dr. Somerville’s report provided the following conclusions:  
Conclusions/Opinion/Response to Question(s):  
I concluded in my Initial Physician Case File Review Memo that the exposures outlined  
in the Occupational Hygiene Exposure Assessment, at that time, likely did not  
significantly contribute to [the worker’s] brain cancer. I concluded in my Subsequent  
Review Memo of June 15, 2015 that there was insufficient medical and scientific  
evidence the exposures outlined in the Occupational Hygiene Assessment of February 3,  
2015 significantly contributed to [the worker’s] glioblastoma multiforme. I had noted that  
ionizing radiation has been established as a risk factor for glioblastoma multiforme,  
however, the evidence is more limited at the level of the specific histologic type of tumor,  
particularly for low to moderate dose settings. Furthermore, I noted that a possible  
association between occupational exposure to extremely low frequency magnetic fields  
and brain tumors has been examined in a number of studies, with IARC concluding that  
the evidence was inadequate to classify extremely low frequency magnetic fields as a  
carcinogen for brain tumors. A new Occupational Hygiene Review is on file with respect  
to [the worker’s] potential for ionizing and non-ionizing radiation exposures with the  
[accident employer]. The most recent review states [the worker’s] employment records  
did not indicate he was located in building 21 where ionizing radiation exposure could  
have occurred and none of the [the worker’s] job titles suggested he performed work as a  
radiographer or operated non-destructive testing equipment and as such, it does not  
appear he was directly exposed to known sources of ionizing radiation. Additionally, the  
[worker’s] employment records did not suggest he was located in work areas where non-  
ionizing radiation exposure could have occurred, and none of his job titles suggest that he  
performed high amperage testing of motors or generators.  
Given there is no evidence of significant exposure at work to ionizing radiation, I cannot  
conclude [the worker’s] brain cancer (glioblastoma multiforme) is work-related.  
[49]  
I have reviewed the medical information that was included in the case materials and I  
conclude that the worker’s treating physicians who treated him for brain cancer did not directly  
or explicitly address the issue of causation in relation to the worker’s brain cancer.  
(iii) Applicable law and policy  
[50]  
[51]  
The worker was diagnosed with brain cancer/glioblastoma multiforme (GBM) in 2012.  
Accordingly, the worker’s entitlement to benefits in this appeal, through his estate, is governed  
by the Workplace Safety and Insurance Act, 1997.  
The Board does not have a policy which applies to GBM and related occupational  
exposures. Accordingly, this appeal must be determined according to the facts of the case and  
the relevant medical and scientific evidence using the disablement section of the definition of  
“accident” under s. 2(1) of the Act.  
[52]  
General entitlement to benefits is governed by section 13:  
13(1) A worker who sustains a personal injury by accident arising out of and in the  
course of his or her employment is entitled to benefits under the insurance plan.  
(2) If the accident arises out of the worker’s employment, it is presumed to have occurred  
in the course of the employment unless the contrary is shown. If it occurs in the course  
of the worker’s employment, it is presumed to have arisen out of the employment unless  
the contrary is shown.  
Page: 18  
Decision No. 1642/21  
[53]  
[54]  
The statutory presumption set out in section 13(2) does not apply to an injury by  
disablement. See, for example, Decision Nos. 268, 1987 1992 (ON WSIAT) and 42/89,  
1989 2559 (ON WSIAT).  
Tribunal jurisprudence applies the test of significant contribution to questions of  
causation. A significant contributing factor is one of considerable effect or importance. It need  
not be the sole contributing factor. See, for example, Decision No. 280, 1987 1996 (ON  
WSIAT).  
(iv) The issue under appeal  
[55]  
[56]  
The sole issue to be determined in this appeal is whether the worker, through his estate,  
has initial entitlement to benefits for glioblastoma multiforme (GBM), a type of brain cancer, as  
a result of his occupational exposures while employed by the accident employer.  
(v) Analysis  
At the hearing, I discussed with the estate’s representative the question of whether this  
was an appropriate case to refer to Tribunal Medical Assessor. The estate’s representative  
indicated during his submissions that he believed that, in light of the legal considerations, the  
evidence on file was adequate and sufficient to determine the appeal. I agree with the  
representative that the evidence in this case is sufficient to determine the appeal. Accordingly,  
this appeal was not referred to a Tribunal Medical Assessor to obtain additional medical  
information.  
[57]  
My approach to the analysis of the worker’s entitlement to benefits in this appeal will be  
to focus initially on the worker’s exposures which were identified as potential factors which  
could have contributed significantly to the development of the worker’s cancer. These will be  
the exposures identified in the occupational hygiene exposure assessments carried out by  
Mr. Chung and also identified by Dr. Kerin’s report, dated May 7, 2012. The exposures  
indicated in the report of the Advisory Committee were also considered. This analysis will also  
address a report, dated January 9, 2020, prepared by Paul A. Demers, Ph. D., Occupational  
Cancer Research Centre, Ontario Health, entitled “Using Scientific Evidence and Principles to  
Help Determine the Work-Relatedness of Cancer”, which the estate’s representative submitted  
identified factors which tend to result in the under recognition of work-related cancers.  
[58]  
Should this initial analysis determine that, on a balance probabilities, one or more of the  
worker’s work exposures, while he was employed by the accident employer, made a significant  
contribution to the development of his GBM, entitlement to benefits for GBM will be in order.  
Should the analysis not result in a determination that one or more of the worker’s work  
exposures made a significant contribution to the development of his cancer, I will consider the  
information about the rate of incidence of GBM during the years when the worker was employed  
by the accident employer. It was the submission of the estate’s representative that the incidence  
of GBM at the employer’s production facility significantly exceeded the rate in the general  
population and that this excessive rate of incidence should be considered as a basis of entitlement  
even in the absence of strong evidence of causation by specific factors, particularly in light of the  
decision of the Supreme Court of Canada in British Columbia (Workers’ Compensation Appeal  
Tribunal) v. Fraser Health Authority, 2016 SCC 25, [2016] 1 S.C.R. 587.  
Page: 19  
Decision No. 1642/21  
[59]  
I note that it was the submission of the estate’s representative that the Workplace Safety  
and Insurance Act, 1997 (“the Act”), includes a provision which creates a presumption for  
persons employed as firefighters. Section 15.1 of the Act provides that if such a worker suffers  
from or is impaired by a disease listed in the regulations (which include “primary-site brain  
cancer”) “the disease is presumed to be an occupational disease that occurs due to the nature of  
the worker’s employment as a firefighter…” It was the submission of the estate’s representative  
(and also the view of Dr. Kerin, in his report dated May 7, 2012) that the worker’s exposures in  
his employment with the accident employer were comparable to that which would be  
experienced by a firefighter, and that the worker ought to be given the benefit of this  
presumption. I will also address this submission in my analysis.  
[60]  
From my review of the materials prepared by Mr. Chung, I conclude that the worker had  
potential for exposure to:  
Epoxy Resins/Process Emissions;  
Organic Solvents;  
Combustion byproducts; and  
Exposures from TIG welding, including magnetic radiation  
[61]  
[62]  
Mr. Chung also considered the worker’s potential exposure to ionizing radiation, but  
concluded that the worker did not have significant exposure to ionizing radiation.  
Dr. Kerin’s report focused on the worker’s potential workplace exposure to:  
Lead;  
Vinyl chloride;  
PAHs;  
Ionizing radiation;  
Solvents/Benzene; and  
Arsenic  
(a) Lead Exposure  
[63]  
Dr. Kerin’s report, dated May 7, 2012, referred to a study prepared by Edwin van  
Wijngaarden and Mustafa Dosemeci, published in Int. J. Cancer: 119, 1136-1144 (2006), which  
“evaluated the association between potential occupational lead exposure and the risk of brain  
cancer mortality in the National Longitudinal Mortality Study (NLMS), which is a prospective  
census-based cohort study of mortality among the noninstitutionalized United States population  
(1979-1989).” Dr. Kerin noted that the study disclosed that “brain cancer mortality rates were  
greater among individuals in jobs potentially involving lead exposure as compared to those  
unexposed” and that “brain cancer risk was greatest among individuals with the highest levels of  
probability and intensity” of exposure to lead. Dr. Kerin concluded that “These findings provide  
further support for an association between occupational lead exposure and brain cancer  
mortality, but need to be interpreted cautiously due to the consideration of brain cancer as one  
disease entity and the absence of biological measures of lead exposure.”  
Page: 20  
Decision No. 1642/21  
[64]  
I also note that Mr. Chung identified lead as a potential process emission exposure for the  
worker in the context of :  
“mild steel welding” which could produce “a variety of metal fumes including  
cadmium, lead and copper”;  
“a lead pot used to coat copper wires, welding and brazing”; and  
“The work process in building #22 involved the application of various types of  
coatings and cladding onto the wires, including lead a steel cladding [sic—lead and  
steel cladding ?]”  
[65]  
[66]  
In addition, Mr. Chung’s further report, dated February 3, 2015, which considered the  
worker’s probable exposures associated with his work activity of TIG welding, noted that “no  
information was available to suggest that the worker’s TIG welding involved base of filler metals  
that contained lead.”  
Dr. Somerville considered Dr. Kerin’s report, in his Board memo, dated January 8, 2013.  
His memo noted caution should be exercised in considering the epidemiological literature  
associated with occupational risk factors related to the development of brain cancer, noting that  
“much of the epidemiological research, especially older studies, has tended to group all brain  
tumors together which is problematic since various types of tumors appear to have different  
causes and risk factors.” The memo also noted that, in addition, “the data is often inconsistent  
and limited by small numbers of cases and inadequate or absent exposure data.” After  
recounting the “non-modifiable” risk factors for GBM, which were “male sex, age over 50,  
genetic predisposition and white ethnicity”, the memo noted that “proposed modifiable risk  
factors for brain tumors” have included “exposure to some chemicals such as vinyl chloride,  
petrochemicals and lead.” It stated, however, that “the only firmly established modifiable risk  
factor though is ionizing radiation exposure, especially among children.”  
[67]  
Dr. Somerville considered a study by “Bhatti and colleagues” which “looked at the  
possibility that lead exposure was causative in GBM formation.” Dr. Somerville noted that “the  
conclusion was that the results of the study showed some evidence that lead may cause  
glioblastoma multiforme and meningioma through mechanisms related to oxidative damage, but  
the results need to be confirmed in other populations” and that “without occupational hygiene  
data incorporated into the study, the results are hardly verifiable though.”  
[68]  
One of the listed references to Dr. Somerville’s memo was a journal article, authored by  
Hiroko Ohgaki and Paul Kleihues P. entitled “Epidemiology and etiology of glioma” published  
in Acta Neuropathol (205)109: 93-108, which was also included in the case materials. The article  
noted that a study by Cocco et al. which “applied a job-exposure matrix for lead to occupational  
and industry codes given on the death certificate of 27,060 brain tumour cases [and control  
cases]” and found that “as significant twofold excess brain tumor risk was seen among Caucasian  
men with high levels of lead exposure…” The article noted, however, “in contrast, in a cohort of  
male US workers exposed to lead, mortality was significantly raised for cancers of the stomach,  
lung, and endocrine organs, but not for CNS tumors [i.e., central nervous system tumors, which  
would include brain tumours].” The article noted in its abstract that:  
Several occupations, environmental carcinogens, and diet (N-nitroso compounds) have  
been reported to be associated with an elevated glioma risk, but the only environmental  
Page: 21  
Decision No. 1642/21  
factor unequivocally associated with an increased risk of brain tumors, including gliomas,  
is therapeutic X-irradiation.  
[69]  
[70]  
Dr. Somerville also indicated that the article referenced in Dr. Kerin’s report, which  
pertained to lead exposure, “does not distinguish between histopathologic types of brain cancer”,  
that “it did not have any biological measures of lead exposure either” and that “its results do not  
provide evidence of increased risk of GBM from lead exposure.”  
From my review of the case materials which address a potential relationship between  
exposure to lead and the development of GBM, I conclude that it is not probable that the worker  
had significant exposure to lead in his employment with the accident employer, and that it is not  
probable that any occupational exposure that the worker had to lead made a significant  
contribution to the development of his GBM.  
[71]  
I find that, if the worker had exposure to lead, it was most likely related to his work as a  
welder. The occupational hygiene assessment report, dated September 17, 2012, noted that the  
worker performed “mild steel welding” and that “a variety of metal fumes including cadmium,  
lead and copper” could be associated with this work. In this regard, the occupational hygiene  
assessment in relation to the worker’s TIG welding, dated February 3, 2015, prepared by  
Mr. Chung, indicated that “metal fumes from TIG welding can originate from the base metal,  
filler metal and electrode”. That memo stated, however, that “no information was available to  
suggest that the worker’s TIG welding involved base or filler metals that contained lead.”  
[72]  
[73]  
I find that there was potential for the worker to be exposed to lead fumes when  
performing TIG welding because lead was employed, in some circumstances, as the base or filler  
metals used in the welding. In the worker’s case, however, there was no evidence before me that  
lead was used in this manner at the employer’s production facility. The evidence indicated that  
the worker was only a part time welder, and this would also limit his exposure.  
I also note that the OH Exposure Assessment, dated September 17, 2012, indicated that  
the worker had other potential exposures to lead. It indicated that the lower floor of the  
Armature department “contained other work processes including a lead pot used to coat copper  
wires…” It also stated that, in Building #22, which was part of the Wire and Cable department,  
work processes “involved the application of various types of coatings and cladding onto the  
wires, including lead a steel cladding and jute/burlap. a rubber and PVC sheaths [sic –  
“…including lead and steel cladding and jute/burlap and rubber and PVC sheaths” ?].  
Mr. Chung noted, however, that “no information was available to suggest that the worker was  
routinely located near the rubber or PVC handling areas during his tenure in building #22.”  
[74]  
Based on the OH exposure assessment information, prepared by Mr. Chung, I conclude  
that, apart from exposures to which the worker was subject as a result of performing TIG  
welding, which I have addressed above, it is not probable that the worker had significant  
exposure to lead. Apart from his TIG welding, the OH exposure assessment from Mr. Chung  
indicated that the worker’s other potential exposure to lead occurred while he was working in  
building #22. The assessment stated that the worker was located in Building #22 for a total of  
4.75 years and that “while in this building the worker was involved with the winding and  
inspection of large magnetic cables (0.83 yr.), brazing (3.57 yr.) and operation of a forklift (0.25  
yr.).” I find that it is not probable that the worker had significant exposure to lead during his  
tenure in Building #22, either while performing TIG welding, or due to the other work processes  
in Building #22, related to the production of wire and cable. I make this finding based on the  
Page: 22  
Decision No. 1642/21  
occupational hygiene information related to TIG welding, as noted above, and based on the work  
processes in which the worker was employed in the Wire and Cable department.  
[75]  
Finally, and perhaps most significantly, I accept Dr. Somerville’s opinion, as stated in his  
memo, dated January 17, 2013, that “there is no accepted evidence in the current medical  
literature that the agents cited by OHCOW (with the exception of ionizing radiation), either  
alone or combined, could have resulted in the IW's glioblastoma multiforme.” It follows that the  
current medical literature does not provide support for the view that, if the worker had significant  
exposure to lead (and I find that the occupational hygiene assessment information does not  
support such a finding, on a balance of probabilities), that such exposure significantly  
contributed to the development of his GBM.  
(b) Exposure to Polyvinyl chloride (PVC/PVMs)  
[76]  
Dr. Kerin’s report, dated May 7, 2012, stated that the worker was exposed to PVCs,  
primarily on the basis that “coating of electric wire manufacturing in the Formex area of the  
Wire and cable in [the accident employer] was manufactured using PVC made extensive use of  
PVC covering.” Dr. Kerin noted that “PVC itself is said to be ‘safe’, however, when heated its  
off-gassing/outgassing of contaminants/breakdown products or additives and breakdown  
products e.g. VMC, dioxins and phthalates or plastic softeners are considered to be the principle  
health risks in the heating of PVC.” Dr. Kerin noted that “VCM [sic – VCM or vinyl chloride  
monomer ?] is considered a likely carcinogenic agent in the development of brain cancer.” He  
also noted that the worker “would also have been exposed to polyvinyl chloride degradation as it  
was heated in ovens” and that “the off-gassing of vinyl chloride…is considered to be a risk factor  
in developing brain cancer.”  
[77]  
I have reviewed the OH exposure assessment reports prepared by Mr. Chung.  
Mr. Chung’s report, dated September 17, 2012, stated that the Wire and Cable department  
included “PVC mixers” in building #26, but stated that the “work history information did not  
suggest that the worker was located in this building. It also noted that “the work process in  
building #22 involved the application of various types of coatings and cladding onto the wires,  
including lead a steel cladding and jute/burlap, a rubber and PVC sheaths” but added that “No  
information was available to suggest that the worker was routinely located near the rubber or  
PVC handling areas during his tenure in building #22.” I note that neither the report, dated  
September 17, 2012, nor any of the other OH exposure reports prepared by Mr. Chung, indicated  
that the worker had occupational exposure to “off-gassed” or “outgassed” PVC or other forms of  
polyvinyl chloride. Had there been information available to Mr. Chung about “off-gassed” or  
“outgassed” PVC, I would have expected the information to have been presented in the 2012  
report, under the heading, “Process Emissions”, however, this portion of the report does not  
indicate that the worker was exposed to “off-gassed” or “outgassed” PVC. The only reference to  
PVCs in this portion of the report is the statement that “no information was available to suggest  
that the worker was routinely located near the rubber or PVC handling areas during his tenure in  
building #22.”  
[78]  
In his memo, dated January 17, 2013, Dr. Somerville stated that “exposure to some  
chemicals such as vinyl chloride” have been proposed as a risk for brain tumours, but that “the  
only firmly established modifiable risk factor though is ionizing radiation exposure, especially  
among children.” In discussing Dr. Kerin’s report, Dr. Somerville noted that “no research  
studies were provided to support increased risk of GBM due to polyvinyl chloride exposure, only  
Page: 23  
Decision No. 1642/21  
information regarding increased risk of liver cancer” and that “it is problematic to conflate  
different types of cancer when discussing causation.” Dr. Somerville indicated that “there is no  
increased risk confirmed in the current medical literature for exposure to… vinyl chloride…as  
suggested by the OHCOW Addendum Report.”  
[79]  
On the basis of my review of the OH Exposure Assessment reports, prepared by  
Mr. Chung, and the information provided by Dr. Kerin and Dr. Somerville, I conclude that it is  
not probable that the worker had significant exposure to PVC/PVMs in the form of “off-gassed”  
or “outgassed” PVC. Further, I find that if the worker did have a level of exposure to this agent,  
based on the available current medical literature, it is not probable that such exposure contributed  
significantly to the development of the worker’s GBM.  
(c) Exposure to Polycyclic Aromatic Hydrocarbons (PAHs) including  
solvents, combustion products and other process emissions  
[80]  
The case materials included limited information which referred explicitly to the worker’s  
exposure to PAHs, or an increased risk of GBM due to exposure to PAHs. I note that  
Dr. Kerin’s report stated that “review of the literature with respect to causation of brain cancers  
suggests that there are several toxins capable of increasing the risk of developing malignant  
changes such as GBM…” The report went on to list six agents in bullet points, one of which was  
“PAHs” (the other listed agents were lead, vinyl chloride, ionizing radiation, solvents/benzene  
and arsenic). Later in the report, it included the subheading “Polycyclic Aromatic Hydrocarbons  
(PAHs)”, under which the report stated, “GBM malignant changes trend is found in occupational  
exposure to solvents and petroleum products”, however, following that sentence, the report  
discussed the issue of the worker’s potential exposure to ionizing radiation, and the report did not  
refer again to PAHs.  
[81]  
In this context, I interpret Dr. Kerin’s report to imply that Dr. Kerin was considering the  
various solvents to which the worker was exposed in his employment with the accident employer  
to be PAHs. Although this is not clear from the case materials, I will address the question of  
whether the worker’s exposure to solvents made a significant contribution to the development of  
his GBM under this subheading. I note that Mr. Chung’s report, dated September 17, 2012,  
referred to the worker’s potential exposure to “Process Emissions”, “Organic solvents” and  
“Combustion products” and, (with the exception of exposures related to brazing and welding,  
which is addressed below) these will be addressed in this portion of these reasons. Mr. Chung  
identified the following exposures in the report:  
Process Emissions: The lower level of Armature contained a variety of processes,  
including the VPI tanks, epoxy cure ovens, metal coating, silver brazing and mild steel  
welding (a variety of metal fumes including cadmium, lead, and copper).  
Organic solvents: a variety of cleaning solvents were used, including “1500 Thinners”  
(toluene), methyl ethyl ketone, acetone, mineral spirits and possibly trichloroethylene as a  
degreaser. Other organic vapours could have included vinyl toluene and epoxy resins.  
Information from Lal (2006) noted that MSDS information indicated the epoxy adhesive  
(L-6277 A) contained diglycidyl ether /bisphenol A epoxy (60- 100%) and butyl glycidyl  
ether (10-30%); decomposition byproducts include aldehydes, ketones, chlorinated  
hydrocarbons. Epoxy hardener might have included L-5142 B contained  
triethylenetetramine(l00%).  
Combustion products: a variety of lubricating oils, coatings and cleaning solvents came  
into contact with the heating elements of the coil presses. This probably resulted in some  
Page: 24  
Decision No. 1642/21  
combustion by-products, such as aldehydes, nitrogen oxides, carbon monoxide and  
carbon dioxide.  
[82]  
Mr. Chung’s 2012 report commenced with a brief Summary, which explained in general  
terms, the nature of the worker’s potential exposure to organic solvents, combustion products  
and other process emissions. This portion of the report stated:  
A review of the available process and work history information suggest that the worker  
was potentially exposed to epoxy resins, especially during his tenure in Armature, from  
1989 to 2007. In addition to these emissions the worker was potentially exposed to  
organic solvents, combustion by-products from various heated processes such as brazing,  
oven and furnaces during his tenures in Armature, wire and cable and Formex.  
[83]  
The report went on to describe the specific circumstances in which the worker was  
subject to these occupational exposures. One of the processes in which the worker was  
employed which was considered as a potential source of exposure was the manufacturing of coils  
which were used in the production of large and small motors. After the coils were assembled,  
they were placed in VPI (vacuum pressure impregnation) tanks, and subsequently cured in  
ovens. The process was described in Mr. Chung’s report, as follows:  
…The low voltage coils were constructed as follows: Bonding paper was placed in  
between layers of long copper bars. The layered bars were then placed in a heated press,  
wrapped with a mylar tape and formed into an oval hoop. The hoop was then placed in a  
spreader that formed it into the required shape while it was manually wrapped using a  
variety of insulating tapes, such as tape coated with epoxy resins. A 1973 MOL  
[Ministry of Labour] report noted that the mica tape contained an epoxy resin consisting  
of a phenol-formaldehyde polymer etherified with glycidal groups. In addition, several  
ancillary processes were performed upstairs. These processes included the dipping of  
fibreglass tape into a liquid resin; silver brazing copper wires and other components; and  
the manual brush application of resins onto the coils. A 1987 report from the employer  
noted that a portion of the DC armatures were dipped in a resin (lsonel 51) containing  
xylene and mineral spirits.  
The assembled coils were then transported to the lower floor. While in this area the high  
voltage coils were connected into the stators and placed in VPI tanks. The vacuum-  
pressure tanks impregnate the coils assembly using an unsaturated polyester resin with  
vinyl toluene. An employer report suggested that during the latter part of the 1980s the  
VPI process used tertiary butyl styrene to dilute the vinyl toluene resin. During the early  
1970's the MOL noted that this process used polyester or epoxy resins containing the  
catalyst boron trifluoride-monoethylamine. The coated coils were allowed to cure prior to  
shipment to the next process building. In addition, the lower floor contained other work  
processes including a lead pot used to coat copper wires, welding and brazing; metal  
grinding that was conducted in a large walk in booth; and epoxy coating process that  
involved the manual application of an epoxy resin onto coils, the coils were then baked in  
a large oven. An MOL report from 1976 indicated that 1" strips of asbestos boards were  
cut using ban saws. In addition, a 1957 MOL report suggested that the coil building  
process involved the annealing of copper bars used during the assembly of the coils. Prior  
to annealing, the bars were clean using a cold degreasing tank that contained  
trichloroethylene. The bars were then soaked in a sodium nitrate-nitrite salt bath and  
finally quenched in water. Information contained in the MOL report suggest that this  
process might have occurred in Armature, however, the exact location and period of  
operation was not available.  
[84]  
Mr. Chung’s report noted that “the worker was located in Armature (building #7) for a  
total of about 17.5 years.” The report indicated that for about 11.75 of his years spent in the  
Armature department, the worker performed the job of “Wind, Wedge & Connect (VPI)”. The  
Page: 25  
Decision No. 1642/21  
report stated that, although there was no job descriptions for the “Wind, Wedge & Connect  
(VPI)” job, “it was assumed that [the worker] might have been involved with the VPI process as  
described above.”  
[85]  
[86]  
Given the information included in the case materials, and the testimony provided by  
Mr. D. at the hearing, I find as a fact that the worker was involved in the VPI process, as  
described in the 2012 report prepared by Mr. Chung.  
Mr. Chung’s 2012 report indicated that, in addition to the occupational exposures  
associated with the coil building and VPI processes, the worker was also potentially exposed to  
solvents during his years in the employer’s wire and cable department, in that, during the  
manufacturing of wire, the wire was “cleaned using an organic solvent/soap solution”. The  
report suggests, however, that this work was performed in Building #26 and that “work history  
information did not suggest that the worker was located in this building.”  
[87]  
[88]  
Mr. Chung’s 2012 report also indicated that the worker was employed in the employer’s  
Formex department, and that the work processes employed in the Formex department “involved  
cleaning surface impurities from wires.” The report indicated that “a varnish was then applied to  
the surface of the wire via drip” and that excess varnish was removed from the wires by passing  
it through a series of dyes, and that “finally, the coated wires passed through a bake oven.”  
Near the conclusion of the 2012 report, under the heading “Exposure Assessment”,  
Mr. Chung noted that the worker had exposure to the following solvents, combustion products  
and process emissions:  
Epoxy resin associated with the work processes in the Armature department,  
including exposures from the VPI tanks, to which the worker “was potentially  
exposed on a routine basis…via airborne vapours and possibly via dermal contact.”  
The report indicated that the coatings were polyester or epoxy resin and that “the  
polyester resin [contained] vinyl toluene.”  
Organic solvents used in the Formex process in Building #24 which applied varnish  
coatings onto copper cables. The report indicated that the composition of these  
coatings was not available, although other information indicated that “the Formex  
process involved the use of several organic solvents, including MEK [methyl ethyl  
ketone] and toluene  
Combustion byproducts from various heated processes such as welding, various  
ovens and furnaces.  
[89]  
[90]  
I also note that, in his testimony, Mr. D. referred to fires that occurred at the employer’s  
production facility, including a large fire that arose in 1972 when a VPI tank “blew up”, as well  
as smaller fires that workers extinguished on their own on about a monthly basis. I have taken  
this information into account as it relates to the worker’s exposure to combustion byproducts.  
Dr. Somerville’s memo, dated January 17, 2013, accepted the exposures identified by  
Mr. Chung, noting that the worker was “potentially exposed to epoxy resin, organic solvents and  
combustion by-products, including from welding.” The memo concluded, however, that “there  
is no increased risk [for GBM] in the current medical literature for exposure to lead, vinyl  
chloride, PAHs, or arsenic, as suggested by the OHCOW addendum report.” The report also  
stated, near its conclusion, that “there is no well well-established scientific evidence that any of  
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Decision No. 1642/21  
the exposures as outlined in the Occupational Hygiene Exposure Assessment report  
[Mr. Chung’s report dated September 17, 2012] likely significantly contributed to the [the  
worker’s] diagnosis of glioblastoma multiforme.”  
[91]  
At the hearing, the estate’s representative referred to six medical journal articles which  
were included in the case materials. The representative indicated that this literature had been  
provided to him as information that was used in developing the legislative presumptions that  
have been enacted in favour of firefighters. These six articles were:  
An Analysis of Occupational Risks for Brain Cancer, Brownson, et al., AJPH  
February 1990, Vol. 80, No. 2;  
Occupation, Exposure to Chemicals and Risk of Gliomas and Meningiomas in  
Sweden, Navas-Acient, et al., American Journal Of Industrial Medicine, 42:214-  
227 (2002);  
Epidemiology and etiology of gliomas, Ohgaki, et al., Acta Neuropathol (2005)  
109: 91-108;  
Epidemiology of Brain Tumors, Ohgaki; Cancer Epidemiology, (M. Verma, ed)  
pp.323 -342 (Chapter 14);  
Occupational Risk Factors for Brain Cancer in Canada, Pan, et al., Occupational  
Hazards and Brain Cancer, JOEM, Vol 47, Number 7, July 2005  
Occupational Medicine Forum, Guy Perry Jr., JOEM, Vol. 37, Number 9,  
September 1995.  
[92]  
[93]  
[94]  
The article by Brownson, et al., indicated that increased risk for brain cancer could be  
observed in white collar occupations as well as agricultural crop production, printing and  
publishing and brick masons and tile setters. The abstract for the article stated that “this  
exploratory study indicates a need for further studies of occupational risks of brain cancers”.  
The article by Navas-Acient, et al., noted that exposure to petroleum products showed a  
possible association with glioma among men and that although exposure to some solvents and  
PAHs has been related to brain cancer, no association with these substances was found in the  
data developed by the authors.  
The first article by Ohgaki, et al, noted that several occupations, environmental  
carcinogens, and diet (N-nitroso compounds) have been reported to be associated with an  
elevated glioma risk, but the only environmental factor unequivocally associated with an  
increased risk of brain tumors, including gliomas, is therapeutic X-irradiation.  
[95]  
[96]  
Similarly, the second article by Ohgaki (which appears to be a chapter in a textbook)  
included similar information indicating that the only environmental factor unequivocally  
associated with an increased risk of brain tumors, including gliomas, is therapeutic X-irradiation.  
The article by Pan, et al., stated that an increased risk of brain cancer might be associated  
with exposure to asbestos, benzene, mineral or lubricating oil, isopropyl oil, and wood dust and  
with the following occupations: teaching; protective service; metal processing and related jobs,  
and metal shaping and forming; knitting in textile processing; construction trades; and transport  
equipment operating. The article stated that the study suggested a possible role for occupational  
exposure in the etiology of brain cancer.  
Page: 27  
Decision No. 1642/21  
[97]  
The article by Perry, was primarily related to a possible connection between brain cancer  
and electrical utility work. It stated that recent studies have implicated firefighting as a risk factor  
for increased mortality because of brain cancer, but that “not all studies that have shown  
increased risk include analyses of the exposures during the latent period” and that “because of  
the small number of cases present in many studies, it is difficult for the results to be statistically  
significant.”  
[98]  
I conclude from these articles that some studies have shown an elevated risk for exposure  
to some of the solvents, combustion products and other process emissions, however, I find that  
they do not provide evidence which could be the basis of a finding on a balance of probabilities  
that the worker’s occupational exposures made a significant contribution to the development of  
the worker’s GBM. In some instances, the studies provide some evidence of elevated risk for  
brain cancer from environmental exposures, however, the studies indicated that a connection was  
a possibility rather than a probability. Some studies noted that because brain cancer is generally  
a rare condition it may be difficult for a study to generate statistically significant results  
[99]  
From my review of the OH assessment data prepared by Mr. Chung, the medical  
information prepared by Dr. Somerville and Dr. Kerin, the epidemiological articles that were  
included in the case materials, including the medical literature referenced immediately above, I  
conclude that the evidence does not support a finding that it is probable that the worker’s  
exposure to PAHs, including, solvents, combustion products and other process emissions, made a  
significant contribution to the development of his GBM.  
(d) Other possible environmental exposures  
[100]  
The 2017 Advisory Committee Report, referred to above included (at page 30 of the  
report) a list of about 41 “known chemicals used or produced” at the employer’s production  
facility. Most of the agents on this list are either explicitly included in the group of exposures  
identified in Mr. Chung, or fall within the categories of exposures identified by Mr. Chung as  
“process emissions”, “organic solvents”, or “combustion products” in his 2012 OH Exposure  
Assessment. There are other substances listed, which may not have been included by  
Mr. Chung, such as asbestos, copper, hydrogen cyanide, chromic acid, dicumyl peroxide, as well  
as other agents. From my review of the case materials there was not significant information  
included in the case about whether exposure to these other agents could make a significant  
contribution to the development of the worker’s GBM. I find that the evidence before me did not  
include persuasive information which would cause me to conclude that any of the agents listed  
on page 30 of the report made a significant contribution to the development of the worker’s  
GBM.  
[101]  
One substance which is not included on the list on page 30 of the report, which was  
otherwise referenced in the materials is mercury. I note that Mr. Chung’s 2012 report noted that  
“mercury testing pots” were present in Building #26, however, Mr. Chung noted that the “work  
history information did not suggest that the worker was located in this building.” Another  
document, which was included in the materials, was entitled “[Accident employer] Work history  
for [the worker]”. The document included four pages, each page signed by the worker. The  
document appears to present information provided by one of the worker’s children, given that  
several of the entries in the document refer to the worker as “Dad” (e.g., “Dad tried to take all the  
necessary precautions to keep himself safe over the years…”) In relation to mercury exposure  
the document stated:  
Page: 28  
Decision No. 1642/21  
If you had a break out on the test pod on the machine which was full of mercury it could  
easily land in your mouth and you would ingest mercury  
[102]  
[103]  
The Advisory Committee Report also referred to a “Mercury Test Area” where “wire was  
run through open mercury trough” and that “workers used bare hands to draw hot wire through  
trough”.  
I am not able to conclude, however, that the worker had significant exposure to mercury  
in his employment with the accident employer. There was evidence to indicate that mercury was  
present at the employer’s production facility, however, I interpret the information included in  
Mr. Chung’s 2012 report to mean that that mercury testing of wire occurred in Building #26, and  
that the worker’s work history information did not suggest or indicate that the worker was  
located in this building. I note that Dr. Kerin’s report also referred to the presence of mercury at  
the employer’s production facility, but did not indicate that the worker had direct exposure to  
mercury. Dr. Kerin’s report and the information provided by one of the worker’s children  
referred to mercury exposure in terms of “spillage’ and I conclude that if the worker was directly  
exposed to mercury, it would have occurred only on an occasional basis, and such exposure does  
not appear to be directly related to the worker’s regular work processes.  
[104]  
In any event, the materials include limited information related to the question of whether  
mercury exposure significantly contributes to the development of GBM. Mercury exposure as a  
potential factor related to GBM was not highlighted in the information provided by Mr. Chung or  
Dr. Somerville. Dr. Kerin’s report refers to mercury being present at the accident employer’s  
production facility, but does not list mercury among the six bulleted items in the report “capable  
of increasing the risk of developing malignant changes such as GBM” (i.e., lead, vinyl chloride,  
PAHs, ionizing radiation, solvents/benzene and arsenic). Some of the medical literature,  
referenced above, refers to a possible increased risk for brain cancer arising from mercury  
exposure, (e.g., the paper by Navas-Acien, et al, notes at page 218 that “occupational exposure to  
mercury has an important and almost statistically significant RR [relative risk] [emphasis  
added].” This information does not cause me to conclude that, in the worker’s case, any  
exposure to mercury experienced by the worker in his employment with the accident employer  
made a significant contribution to the development of his GBM. Accordingly, I find, on a  
balance of probabilities, that any exposure to mercury experienced by the worker in his  
employment with the accident employer did not make a significant contribution to the  
development of his GBM.  
[105]  
I have also considered whether exposure to arsenic at the employer’s production facility  
could have made a significant contribution to the development of the worker’s GBM. I note that  
Mr. Chung’s 2012 report indicated that “exposures to arsenic were limited to buildings 16A and  
10A” and that “the available work history information did not suggest that the worker was  
located in these buildings.” The case materials did not include other significant information  
indicating that the worker had significant exposure to arsenic in his employment with the  
accident employer. Accordingly, I find on a balance of probabilities that exposure to arsenic did  
not make a significant contribution to the development of the worker’s GBM.  
(e) Exposures arising from TIG welding  
[106]  
I note that the worker’s occupational exposures arising from TIG welding were  
considered by Mr. Chung in his Occupational Hygiene Review, dated February 3, 2015. That  
report indicated that information about the type of base metals and filler metals that were used by  
Page: 29  
Decision No. 1642/21  
the worker in TIG was not available, but that, as noted in greater detail above, there was no  
information available to indicate that the worker was probably exposed to lead in this context.  
The same report noted that arc welders are potentially exposed to magnetic radiation, but that  
“the literature suggests that under normal operating conditions exposures to ionizing radiation  
and magnetic fields are likely to be below occupational guidelines.” In a Board memo, dated  
June 15, 2015, Dr. Somerville reviewed Mr. Chung’s February 2015 report. After reviewing  
some of the literature relating to the relationship between ionizing radiation and low frequency  
magnetic fields, and the development of brain cancer, the memo stated:  
In my opinion there is insufficient medical and scientific evidence the exposures outlined  
in the Occupational Hygiene Assessment dated February 3, 2015 [Mr. Chung’s memo  
which exclusively addressed TIG welding exposures] significantly contributed to [the  
worker’s] glioblastoma multiforme.  
[107]  
[108]  
On the basis of this information I conclude, on a balance of probabilities that the worker’s  
exposures from TIG welding did not make a significant contribution to the development of his  
GBM.  
(f) Exposure to ionizing radiation  
From my review of the materials, I conclude that there is a level of epidemiological  
consensus that exposure to ionizing radiation is a factor which is related to the development of  
GBM. This was indicated in all of Dr. Somerville’s memos to the Board, as well as in much of  
the epidemiological literature referenced above. I find, however, that there was no persuasive  
evidence upon which to conclude, on a balance of probabilities, that the worker had significant  
exposure to ionizing radiation in his employment with the accident employer. Accordingly, I  
find on a balance of probabilities that occupational exposure to ionizing radiation did not make a  
significant contribution to the development of the worker’s GBM.  
[109]  
Mr. Chung’s report, dated December 28, 2017, noted that the employer’s production  
facility included a department which produced nuclear products (Building #21) including the  
manufacture of uranium fuel bundles. The report indicated, however, that the worker’s  
employment records did not indicate that he worked in Building #21. There was no other  
significant evidence to support a finding that the worker worked in Building #21 or that he was  
exposed to ionizing radiation in that building. I find that the worker was not exposed to ionizing  
radiation through exposure at Building #21.  
[110]  
Another possible source of ionizing radiation indicated in the materials was as a result of  
exposure to x-rays, which, according to Mr. Chung’s report “were used, by radiographers, to  
perform non-destructive testing of weldments.” Mr. Chung noted that the x-ray inspection of  
welding occurred in the Structural Steel building (Building 14/14A, and that “none of [the  
worker’s] job titles suggested he performed work as a radiographer or operated non-destructive  
testing equipment.” On this basis Mr. Chung concluded that “the available records do not  
suggest the worker was directly exposed to known sources of ionizing radiation at the [name of  
city] site.” I note that Mr. D. also indicated in his testimony at the appeal hearing that welds  
were not x-rayed in the Armature department, but rather at the south end of the Structural Steel  
department, which confirms the information provided by Mr. Chung on this point. In his memo,  
dated January 18, 2018, Dr. Somerville agreed that ionizing radiation did not make a significant  
contribution to the development of the worker’s GBM, on the basis that it does not appear that  
the worker was employed in a capacity where he would be subject to significant ionizing  
radiation exposure.  
Page: 30  
Decision No. 1642/21  
[111]  
[112]  
I find that ionizing radiation did not make a significant contribution to the development  
of the worker’s GBM, on the basis that the evidence does not support a finding that the worker  
was exposed to significant ionizing radiation in his employment with the accident employer.  
(g) Consideration of the Demers Report  
In his submissions at the hearing, the estate’s representative referred to a paper, which  
was included in the case materials, prepared by Dr. Paul Demers, entitled “Using Scientific  
Evidence and Principles to Help Determine the Work-Relatedness of Cancer” (referred to  
hereinafter as the “Demers Report”). The estate’s representative submitted that the paper by  
Dr. Demers, appropriately reflects a robust and pragmatic approach to the adjudication of claims  
for work-related cancer, points out the limitations of scientific epidemiological literature in cases  
where a worker is subject to multiple occupational exposures, and highlights the potential  
synergistic effects of multiple occupational exposures.  
[113]  
The Demers Report was considered previously by the Tribunal in Decision No. 726/15R,  
2021 ONWSIAT 680. In this regard, that decision stated, beginning at paragraph 13:  
The submissions of the worker’s representative in support of the worker’s request for  
reconsideration referred to a report by Dr. Paul Demers, entitled “Using Scientific  
Evidence and Principles to Help Determine the Work-Relatedness of Cancer”. I have  
reviewed this report. The report included an Executive Summary, which included a  
section entitled “Occupational Cancer in Ontario”. This part of the report stated, in part:  
Adjudication and management of occupational cancer claims in Ontario are  
handled by the WSIB's Occupational Disease and Survivor Benefits Program. In  
determining entitlement to compensation for occupational cancers specifically,  
and occupational diseases more generally, the key adjudicative question to be  
resolved is that of causation (i.e., what caused the cancer).  
Three general principles govern how causation is evaluated and entitlement is  
determined:  
1. Employment does not have to be the predominant or primary cause.  
2. Absolute certainty is not required.  
3. The worker is afforded the benefit of the doubt.  
The Executive Summary also highlighted the point that cancer may be caused through the  
synergism of multiple factors. In this regard, the Executive Summary stated:  
Part 3 of the report focuses on the following theories and principles that are  
relevant to determining the work-relatedness of cancer:  
Multi-stage theories of carcinogenesis emphasize the importance of  
considering multiple exposures as well as the time intervals between  
multiple exposures in the carcinogenesis process.  
All cancers are likely to have multiple causes. If these causes are  
independent of each other, we generally assume that the risk of both is  
the sum of the two. However, in some cases there may be synergy  
between causes and the joint effects can be much greater.  
….  
Why the compensation of occupational cancers is so challenging  
In adjudicating a claim, decision-makers seek to determine whether the disease  
is due to the nature of the worker's employment (i.e., is the disease work-  
Page: 31  
Decision No. 1642/21  
related?). Part 4 briefly presents some major challenges faced by the workers'  
compensation system in Ontario and elsewhere.  
These include:  
….  
Exposure to multiple established or suspected human carcinogens is  
common. However, too few epidemiologic studies have looked at the  
impact of multiple occupational exposures because their focus is almost  
always on establishing whether a single agent is, or is not, a cause of  
disease.  
….  
…Although this report may be considered to be new evidence, the report provides  
general information about the manner in which accident claims for occupational disease  
involving a cancer diagnosis should be approached. Neither the report, nor any other  
information submitted in support of the worker’s request for reconsideration, provides  
any new medical information about the worker’s specific case. In contrast, the original  
Panel obtained a medical assessor's report which specifically considered the worker's  
medical and exposure information and relied on it in reaching their conclusions.  
I have considered the three general principles, noted above, cited in Dr. Demers’ paper as  
governing how causation is evaluated and entitlement is determined.  
The first principle is, “Employment does not have to be the predominant or primary  
cause.” The corollary of this principle is that employment factors need only make a  
significant contribution, rather than a predominant or primary contribution to the subject  
condition. This principle is well established in the Tribunal’s jurisprudence (see Decision  
No. 915, 7 W.C.A.T.R. 1 at 134, under the subheading “The Accidental Injury Need Only  
be One of the Significant Contributing Factors”). I am satisfied that the Panel in  
Decision No. 726/15 was aware of this principle and that it was considered in the  
decision…  
The second principle is, “Absolute certainty is not required.” I am satisfied that in  
Decision No. 726/15, the Panel applied the evidentiary standard of “on a balance of  
probabilities” and that it did not deny the worker’s appeal on the basis that there was a  
lack of certainty in relation to causation. The appeal was denied on the basis that is was  
not probable that the worker’s cancer was work-related, according to the applicable  
evidentiary standard. The fact that the Panel applied the standard of proof of “on a  
balance of probabilities” was clearly articulated at paragraphs 3 and 18 of Decision No.  
726/15.  
The third principle cited by Dr. Demers is “The worker is afforded the benefit of the  
doubt.” I interpret this statement of principle to be shortened statement of the principle  
which is codified in section 124(2) of the Workplace Safety and Insurance Act, 1997,  
which states:  
124…  
(2) If, in connection with a claim for benefits under the insurance plan, it is not  
practicable to decide an issue because the evidence for or against it is  
approximately equal in weight, the issue shall be resolved in favour of the  
person claiming benefits.  
A more complete statement of this third principle is that where the evidence for and  
against entitlement is approximately equal in weight, the worker is afforded the benefit of  
the doubt. Given the three central factors which were the basis of the Panel’s decision,  
which are set out above in bullet points, as well as the latency period for any  
occupational exposures, it is apparent that the Panel did not conclude that the evidence  
for and against entitlement was approximately equal in weight. Instead, the Panel  
Page: 32  
Decision No. 1642/21  
concluded on a balance of probabilities that the cancer was not caused by the workplace  
exposures. Accordingly, the principle related to “benefit of the doubt” did not arise in the  
worker’s case.  
I have also considered the information included in the report prepared by Dr. Demers in  
relation to his statement that “all cancers are likely to have multiple causes” and that “in  
some cases there may be synergy between causes and the joint effects can be much  
greater.” As I have indicated, I am satisfied that the Panel in Decision No. 726/15 found  
that there was strong evidence associating the worker’s tongue cancer with HPV (i.e., the  
cellular evidence found on biopsy, the location of the cancer and the latency period of the  
cancer) as well as other evidence which ruled out causation arising from the occupational  
factors (i.e., the latency period was too short for cancer arising from the occupational  
factors). In these circumstances, in the absence of other specific evidence which would  
support the synergistic effect of the occupational factors together with effect of HPV, I  
conclude that it would be speculative to conclude on a balance of probabilities that the  
occupational factors were related to the development of the worker’s tongue cancer. I  
note that the benefit of the doubt does not apply to speculation.  
Accordingly, I am not persuaded that the information included in the report from  
Dr. Demers would change the outcome of Decision No. 726/15, or cause me to conclude  
that the decision included a significant defect in the administrative process or content of  
the decision which, if corrected, would probably change the result of the original  
decision.  
[114]  
[115]  
Similar to the analysis presented in Decision No. 726/15R, although I agree with the  
principles set out by Dr. Demers in his paper, the information presented in the paper does not  
change my analysis on the question of whether the worker’s occupational exposures made a  
significant contribution to the development of his GBM.  
In this case, I have considered the worker’s non-occupational risk factors as well as his  
occupational exposures. In this case, the worker was a non-smoker. As Dr. Somerville pointed  
out in his memo, dated January 17, 2013, the worker was subject to “non-modifiable” risk factors  
for GBM, namely male sex, being over age 50 and his ethnicity. I accept the principle that  
“employment does not have to be the predominant or primary cause.” I have considered the  
worker’s non-occupational risk factors together with his occupational exposures, however, I have  
concluded that, on a balance of probabilities, the worker’s occupational exposures did not make a  
significant contribution to the development of his GBM.  
[116]  
[117]  
I also accept the principle that “absolute certainty is not required.” Throughout the  
analysis set out above, I have indicated that the evidentiary standard in this appeal is “on a  
balance of probabilities”, which is the applicable evidentiary standard in Tribunal appeals.  
I have also considered the application of section 124(2), which provides the worker with  
the “benefit of the doubt” which is the subject of Dr. Demers’ third principle. In this case, I have  
concluded that the evidence for and against entitlement is not approximately equal in weight, and  
based on the evidence before me, I have concluded that it is more probable that the worker’s  
occupational exposures did not make a significant contribution to the development of his GBM  
than it is probable that the occupational exposures made such a significant contribution. Because  
the evidence for and against entitlement is not approximately equal in weight, this case is not one  
in which section 124(2), or the principle that “the worker is afforded the benefit of the doubt.”  
applies  
[118]  
I also agree with the statements in the Demers Report that “all cancers are likely to have  
multiple causes” and that “in some cases there may be synergy between causes and the joint  
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Decision No. 1642/21  
effects can be much greater.” Where the evidence does not disclose that it is probable that an  
occupational exposure made a significant contribution to the development of the cancer, unless  
there is evidence about a particular synergy existing between the occupational exposure and  
another factor which is present, in my view, it would be speculative to allow entitlement on the  
basis of a synergy between or among factors based on the general proposition that “all cancers  
are likely to have multiple causes.” I find the medical and epidemiological evidence in this case  
does not indicate a synergistic effect that would support on a balance of probabilities that the  
worker's GBM was due to work-related factors.  
(h) Conclusions on significant contribution of occupational exposures to the  
development of GBM  
[119]  
For reasons that are provided above, I conclude that the evidence before me does not  
support a finding that the worker’s environmental exposures while he was employed by the  
accident employer between 1965 and 2007 made a significant contribution to the development of  
his GBM. I have indicated that the case materials do not provide information supporting the  
conclusion that the worker’s occupational exposures or potential exposures made a significant  
contribution to the worker’s GBM in relation to following agents:  
lead;  
polyvinyl chloride (PVC/PVMs);  
Polycyclic Aromatic Hydrocarbons (PAHs) including exposures to solvents,  
combustion products and other process emissions;  
mercury;  
arsenic;  
other environmental agents listed in the Advisory Committee Report, such as  
asbestos, copper, hydrogen cyanide, chromic acid, dicumyl peroxide, and other  
agents;  
exposures form TIG welding; and  
ionizing radiation  
[120]  
I make this finding on the basis that the epidemiological and medical information before  
me does not support the conclusion, made on a balance of probabilities, that the worker’s  
exposures while he was employed by the accident employer made a significant contribution to  
the development of his GBM. I also find, on a similar basis that the worker’s occupational  
exposures while he was employed by the accident employer did not, in combination or as a result  
of a synergistic process, make a significant contribution to the development of his GBM.  
Accordingly, I find, on a balance of probabilities, that the worker’s occupational exposures while  
he was employed by the accident employer did not make a significant contribution to the  
development of his GBM.  
[121]  
The case materials also included a medical article entitled “Risk factors for brain tumors”  
authored by Dominique Michaud, Sc.D. and Tracy Batchelor, M.D. M.P.H., which was an  
“Official reprint from UpToDate” a literature review service of Wolters Kluwer. Under the  
subheading “Occupational Exposures” the article stated:  
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Decision No. 1642/21  
A large number of studies have been conducted to examine whether occupational  
exposures are associated with the risk of brain tumors. Although some positive  
associations have been reported, there are many inconsistencies in the literature and  
results are often difficult to interpret given numerous methodologic issues.  
….  
Many studies have focused on electrical, rubber, and petroleum workers, where earlier  
studies had detected strong positive associations; however, the overall findings from  
these studies do not provide strong support for positive associations. No excess mortality  
from brain cancer was detectable in a meta-analysis summarizing risk estimates from 20  
studies of rubber workers (relative risk [RR] 0.90, 95% CI 0.79-1.02) [32]. Similarly, at  
least two meta-analyses have found no significant overall increase in brain cancer  
mortality in petroleum workers. Finally, for electrical workers, while a number of studies  
suggested that individuals in electrical occupations were at increased risk of brain tumors,  
with relative risks ranging between 1.5 and 2.5, other studies did not confirm these  
findings [footnotes not included].  
[122]  
The article concluded with the following bullet points included under the heading  
“Summary”:  
Ionizing radiation is the only firmly established environmental risk factor for  
brain tumors. Cohort studies of atomic bomb survivors and childhood cancer  
survivors have demonstrated that cranial radiation is associated with increased  
risk for a variety of brain tumors, including meningiomas, gliomas, and nerve  
sheath tumors…  
The association between forms of nonionizing radiation, such as low-frequency  
electromagnetic fields and radiofrequency fields, and cancer is less clear, and  
the data do not support an important role for these types of radiation as risk  
factors for brain tumors…  
A small proportion of brain tumors are due to genetic syndromes that confer an  
increased risk of developing tumors of the nervous system. These include  
neurofibromatosis type 1 (NF1), neurofibromatosis type 2 (NF2), von Hippel-  
Lindau syndrome, Li-Fraumeni syndrome (LFS), familial adenomatous  
polyposis, and the basal cell nevus syndrome…Genetic susceptibility has also  
been noted to play a role in determining risk of brain tumors, although  
collectively these variants do not account for a large proportion of risk.  
Possible causative factors that require further investigation include allergies,  
nonionizing radiation, physical and acoustic trauma, and certain infections.  
[123]  
[124]  
I interpret the information included in this article to provide further support for the  
conclusion that the worker’s occupational exposures while he was employed by the accident  
employer did not make a significant contribution to the development of his GBM.  
(i) Incidence rate of brain cancer tumours at the accident employer’s  
production facility from 1976 to 2018  
At the appeal hearing, the estate’s representative made the submission that, should I  
determine that the evidence in relation to the potential contributing causes of the worker’s GBM,  
as alleged by the estate, did not support a finding that the worker’s occupational exposures while  
he was employed by the accident employer made a significant contribution to the development of  
his GBM, I should consider the evidence of the rate of incidence of brain cancer at the  
employer’s production facility around the period of the worker’s employment there. It was his  
submission that the rate of incidence of brain cancer of individuals employed at the facility from  
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Decision No. 1642/21  
1976 to 2018 greatly exceeded the expected rate of incidence of brain cancer in the general  
population, and that this provided evidence that the worker’s occupational exposures while  
employed by the accident employer made a significant contribution to his brain cancer.  
[125]  
In this regard, the case materials included a document entitled “[Name of City – accident  
employer] Claims, Registered 1976 – 2018 with Ca [Cancer]” The document included  
information provided by the WSIB in relation to claims from the accident employer registered  
with the WSIB from 1976 to 2018, which were related to a cancer diagnosis. The document  
indicated that, during this period, 6 claims from the accident employer were registered with the  
Board which were related to brain cancer.  
[126]  
Submissions made by the estate to the Board’s Appeals Branch, dated  
September 16, 2019, which the estate’s representative adopted at the appeal hearing, provided  
the following information:  
Dr. Somerville, in physician consultant review memo 11 outlines incidence rate for  
glioblastoma multiforme diagnoses in the general population is 3.19/100,00 people. The  
incidence rate for brain cancer in Ontario is 7.6/100,000 which includes meningiomas  
and gliomas. According to the WSIB's own numbers, (attached as exhibit 1), from 1976-  
2018 there were no less than 6 brain cancer claims registered with the Board.  
At its height of production, [the accident employer] employed approximately 6600  
workers and gradually decreased from there. I calculated the attributable risk of these as  
due to workplace exposure compared to the incidence rate in the general population of  
Ontario. I calculated this for 3 different estimates of the worker population and converted  
these into an incidence rate per 100,000 population to compare with the Ontario rate for  
brain cancer. The incident rate for Ontario is 7.6/100,000 for that period and the age  
groups selected. Data for Ontario was from the Ontario Cancer Registry for the years  
1997 to 2006 as the years of diagnosis. They are:  
1. 7000 employees the incidence rate for [the accident employer] is 11.2 times higher;  
2. 6000 employees the rate is 13 times higher;  
3. 5000 employees the rate is 15 times higher.  
The numbers provided by WSIB only includes reported brain cancer claims and does not  
include any brain cancer diagnoses not reported to WSIB. On its own, these stark  
numbers represent a staggeringly statistically significant increased incidence rate of brain  
cancer that does not appear to have even been reviewed or considered throughout the  
adjudicative process thus far.  
[127]  
[128]  
The concern that I have with the approach presented in the estate’s submissions at the  
appeal hearing, and in writing to the Board, noted above, is that it does appropriately take into  
account the period of time over which the six brain cancer claims noted occurred.  
I note that, in the information provided by Dr. Kerin, and in the epidemiological studies  
presented in the case materials, incidence rates of cancer are expressed using the statistical unit  
of “person years”. For example, Dr. Kerin stated on page 2 of his report, dated May 7, 2012, that  
“the worldwide incidence of primary malignant brain and central nervous system tumours is  
higher in the developed countries (males 5.9 per 100,000 person years) [emphasis added].  
Similar language is used in the Navas-Acien article, referred to above, which stated on the  
second page of the article:  
The base population for this historical cohort is comprised of all Swedish men and  
women who were gainfully employed at the time of the 1970 census, had also been  
recorded in the 1960 census, and were still alive and over the age of 24 years as on  
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Decision No. 1642/21  
January 1, 1971. This encompassed 1,779,646 men and 1,066,346 women, 25-64 years of  
age at the beginning of the study in 1971, and subsequently followed for 19 years until  
year-end 1989, rendering a total of 33,359,168 and 20,808,750 person-years for men and  
women, respectively [emphasis added].  
[129]  
It is apparent from this passage that the number of “person years” is calculated by  
multiplying the number of persons who were studied by the number of years over which the  
study occurred. A similar approach is also taken in the article by Ohgaki and Kleihues, referred  
to above, which stated on the second page of the article:  
The age-adjusted incidence rates of brain tumors generally tend to be highest in  
developed, industrial countries. In Western Europe, North America, and Australia, there  
are about 6-11 new cases of primary intracranial tumors (including meningiomas) per  
100,000 population per year in men and 4-11 new cases in women [emphasis added]  
[130]  
From the information that was provided by the Board, referred to by the estate’s  
representative in his submissions, one can conclude that six people made claims to the Board for  
brain cancer during the 42 year period from 1976 to 2018. If the information provided by the  
Board (6 brain cancer claims registered over 42 years) is to be compared to the incidence rate in  
the general population, the same units of measurement should be used in order for the  
comparison to be meaningful. Assuming that all six claims involved a diagnosed case of brain  
cancer, the question arises as to the number of people who would need to be included in a 42  
year study, in order to capture all six cases. The total number of people who were employed by  
the accident employer at its production facility between 1976 and 2018 is not information which  
is included in the case materials, and given turnover among workers at the facility from year to  
year, one would expect that it would be a greater number than the 5,000 or 6,000 people who  
were employed in any one year. If, however, only 5,000 persons were studied over 42 years, the  
number of “person years” associated with six brain cancer claims would be 210,000 person  
years.  
[131]  
From the information presented in the case materials, I am not able give weight to the  
submissions presented by the estate’s representative concerning the incidence of brain cancer  
which has developed in workers at the employer’s production facility as compared to the  
incidence of brain cancer in the general population. The submission does not appropriately take  
into account the number of persons to be studied or the duration of such a study, which would be  
necessary to capture the six claims relating to brain cancer arising from the employer‘s facility  
that were registered with the Board from 1976 to 2018.  
[132]  
I have also considered the submissions of the estate’s representative in relation to the  
decision of the Supreme Court of Canada (S.C.C) in British Columbia (Workers’ Compensation  
Appeal Tribunal) v. Fraser Health Authority, 2016 SCC 25 (), [2016] 1 SCR 587. At  
paragraph 3, the decision stated:  
[The three named appellants in the case] were among seven technicians at a single  
hospital laboratory who were diagnosed with breast cancer. Each of them applied for  
compensation under the [British Columbia Worker’s Compensation Act] on the basis that  
the cancer was an “occupational disease”.  
[133]  
At paragraph 10, the decision stated:  
The OHSAH [Occupational Health and Safety Agency for Healthcare in British  
Columbia] reports contained a review of the scientific literature on factors associated  
with the risk of breast cancer, an epidemiological analysis of the cancer cluster among  
workers in the laboratory, and a field investigation into possible exposure among  
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Decision No. 1642/21  
laboratory technicians to potentially carcinogenic substances. They confirmed that the  
number of diagnoses of breast cancer (7 of the 63 workers studied were so diagnosed)  
represented a statistically significant cluster, with a “standardized incidence ratio” for  
breast cancer approximately eight times the rate that would have been expected in the  
general population. As to potential causes, the authors of these reports observed no  
current occupational chemical exposures, but noted that past exposures were “likely  
much higher”, and included one known human carcinogen (Final Report, at p. 35).  
[134]  
As noted, the decision referred to the group of breast cancer cases as a “cluster”. It is  
implicit in the decision that this cluster of breast cancer cases occurred contemporaneously. The  
decision of the British Columbia Court of Appeal, (Fraser Health Authority v. Workers  
Compensation Appeals Tribunal, 2013 BCSC 524) which was the subject of the appeal to the  
S.C.C. noted that:  
Cluster research has shown that elevated rates occur by chance at some geographic  
locations and times. In fact, clusters always occur and it is a statistical phenomenon -  
even when there is no causal factor that is responsible for the increased