Decision #169/07 - Type: Workers Compensation

Preamble

A hearing was held on April 11, 2007 at the request of an advocate, acting on behalf of the worker. The panel discussed this appeal on several occasions, the last one being October 19, 2007.

Issue

Whether or not the claim is acceptable.

Decision

That the claim is acceptable.

Decision: Unanimous

Background

This case was previously the subject of an appeal hearing which took place on June 9, 1999. The issues considered at that time were “Whether the claim for compensation should be adjudicated using the dominant cause test as provided by Section 4(4) of the Act which became effective January 1, 1992” and “Whether the claim is acceptable.” For a complete background of this case leading up to the June 9, 1999 hearing, please refer to Appeal Commission Decision No. 161/99 dated November 23, 1999.

Briefly, the worker filed a claim with the Workers Compensation Board (WCB) related to carcinoma of the tonsil and pharynx which he attributed to his exposure to grinding dust and welding fumes from stainless steel spark arrestors (honeycombs) in his work environment. In February 1994, the WCB’s occupational disease unit denied the claim as it could not establish a relationship between the worker’s occupation as a welder and diagnosis of carcinoma of the tonsil and pharynx. On August 25, 1995, Review Office concluded that the dominant cause of the worker’s disease/condition was not work related. It based its decision on the weight of medical evidence and subsection 4(4) of The Workers Compensation Act (the Act) and the findings of a Medical Review Panel (MRP) which concluded that the worker’s employment was not the dominant cause of his carcinoma.

Review Office reconsidered the case on January 22, 1999 based on further arguments put forth by the worker’s advocate. It found that the claim should be adjudicated using the dominant cause test found in subsection 4(4) as it was amended on January 1, 1992. It found that the MRP did not support the worker’s contention that his employment as a boiler maker was the dominant cause of his diagnosed medical condition. It found that the available evidence did not support the worker’s claim that he had an occupational disease arising out of and in the course of his employment.

On November 23, 1999, the appeal panel concurred that the claim was not acceptable. It stated,

“After consideration of all the evidence, we place the greatest weight on and accept the findings of the Medical Review Panel that there is no clear evidence of a linkage between any of the diagnosed cancers of the left tonsil, the left branchial cyst and the nasopharyngeal areas suffered by the claimant and his occupational exposures in the workplace. As such, we find that there is no “occupational disease” as defined in subsection 1(1) of the Act, and thus we find that there is no “accident” as required under the same subsection. On this basis, we find that the claim is not acceptable, and deny the claimant’s appeal.”

On August 21, 2006, the worker’s advocate requested reconsideration of Appeal Commission Decision No. 161/99 based on a medical report dated June 20, 2006 from an occupational health physician.

The occupational health physician advised that he had a conducted a literature review on the association of occupational exposures and squamous cell carcinoma of the upper airways. He indicated that he had reviewed an epidemiological study which he considered directly relevant to the worker’s case.

In his report, the occupational health physician noted that this study found that pharyngeal cancer was 2.26 times higher in individuals with more than eight years of exposure to welding fumes compared to a control group. The study concluded that welding may cause an increase risk of pharyngeal as well as laryngeal cancer.

More particularly the study found:

“Exposure to welding fumes seemed to increase the RRS for both pharyngeal and laryngeal cancer (table 2). The risk correlated with number of years exposed for both pharyngeal and laryngeal cancer (table 5), but there was no obvious dose-response pattern with cumulative dose. The risk of cancer at both sites was significantly increased after more than eight years of exposure to welding fumes...”

While previous studies had noted a relationship between welding stainless steel and an increased risk of lung cancer due to exposure to chromium, this study concluded the excess of laryngeal and pharyngeal cancer could not be attributed solely to exposure to chromium during stainless steel welding:

“There was increased risks of cancer of the larynx and pharynx after more than eight years of exposure to welding fumes. Welding involves exposure to many chemicals, including metal dust, irritant gases, and PAHs. Welding in stainless steel is associated with an increased risk of lung cancer, due to exposure to hexaavalent chromium. Welding in other materials has not been consistently shown to be associated with an increased risk of lung cancer. The present data indicates that other components of welding fumes may be carcinogenic as well…the excess of laryngeal and pharyngeal cancer cannot be attributed solely to exposure to chromium during stainless steel welding.”

The occupational health physician noted that there is usually a latency period on exposure to carcinogenic substances in the development of cancer. In his view, a latency period of 10 years was a reasonable assumption, although it may be high in some situations.

The occupational health physician concluded that welding exposures were the dominant cause of the worker’s development of cancer of the oropharynx.

“You have worked for more than 14 years as a boilermaker/welder at the time of your initial diagnosis and had 14 years of latency. Of all the studies I reviewed the most pertinent one to your case is that of [physician’s name] and his colleagues because this group specified all included cancers of tonsils in their study population, analyzed pharyngeal cancers separately, reported specifically on welders as an occupational group and welding fumes as an exposure, studies duration of exposure to welding fumes, and had a reasonably large number of cases in welders. This study…supports the position that welding fume exposures can lead to cancers of the oropharynx. In this study prolonged, more than 8 year, welding fume exposure was associated with more than doubling of the risk of pharyngeal cancer.

Alcohol consumption and cigarette smoking have been associated with oropharyngeal cancers. You have a limited smoking and drinking history as detailed in the attached letter. Your work history is consistent with the increased risk or oropharyngeal cancer associated with welding exposures…welding exposures were the dominant cause of your development of cancer of the oropharynx.”

On January 30, 2007, the Chief Appeal Commissioner directed that the Appeal Commission reconsider Decision No. 161/99 as it was his opinion that the study provided by the occupational health physician was new, substantive and material evidence which was not known to the worker at the time of the hearing and could not have been discovered through the exercise of due diligence.

On April 11, 2007, a new hearing was convened to consider the issue of whether or not the worker’s claim was acceptable. On behalf of the worker, his advocate argued that his disease was caused by “his occupational exposure to grinding dust, welding fumes, from working with stainless steel and other metals during the 14 years prior to the discovery and diagnosis of the disease in 1991 and 1992.”

During the course of the hearing, there was a considerable discussion regarding the worker’s exposure to welding fumes including but not restricted to stainless steel welding fumes. The worker indicated that he started with his employer in 1979 and that throughout his work history with his employer as a boilermaker “there has always been welding”. The worker noted, “first of all, the whole shop, there was welding going on from the pipefitters, from the machinists, the boilermakers throughout the whole shop.”

The worker indicated that for part of the early years of his employment with his employer “we did wash out and general repairs on units that were quickly coming through, so there was welding there but not as much.”

In the early 1980s, the worker was primarily involved with locomotives “just rebuild them, making up plates and welding everything back together. It’s just like a body shop for a car. We were just doing locomotives.” During this period of time, the worker estimated that welding involved 30 to 40 percent of his time.

By the mid 1980s, the worker was working in the boiler shop where he worked extensively with stainless steel welding rods. The worker provided a detailed description of his work with honeycombs. “They’re all stainless steel and they have to cut them out, grind, put the new one in, weld it with stainless steel rods.” “The stainless steel welding, I was welding and grinding it, was going on in periods of (eight hours a day) probably two or three weeks or so at one time.” Work in this area continued until the early part of the 1990s.

Following the hearing, the appeal panel wrote to the occupational health physician and asked that he submit all the scientific literature he referred to in his letter of June 20, 2006.

On May 28, 2007, the appeal panel met to discuss the case. It decided that before rendering a decision on the issue of claim acceptability, it would ask an independent medical specialist to provide them with his/her opinion regarding the etiology of the worker’s current medical condition and whether there was scientific evidence to support a conclusion that the nature of the worker’s employment duties and work environment increased the likelihood of him developing his current medical conditions.

A report was later received from the independent specialist dated September 28, 2007 and was forwarded to the worker’s advocate for comment. In his opinion, the independent specialist concluded that in terms of the causal relationship between the worker’s cancer and his work “a causal relationship is probable but not certain”. In his view, the etiology of the worker’s carcinoma was likely multifactorial with about 50 percent being attributable to his work.

In drawing his conclusions, the independent specialist noted a lengthy history of exposure from the late 1970s to the early 1990s “to particulates in the workplace including soot and welding fumes from his work as a boilermaker. Little or no protective gear was used for most of that time, except for the last year when a respirator was used.

In reviewing the scientific literature, the independent specialist concluded:

“There is general acknowledgement that environmental exposure to welding fumes…increases the risk of lung cancer…There is good evidence that nickel exposure (present in welding fumes) can increase the risk of nasal cancer and sinus cancer…Also, there is evidence that other cancers – such as laryngeal cancer – are increased by exposure to welding fumes…There is in-vitro evidence that nickel and chromium present in welding fumes can induce malignant changes in cell cultures and genetic mutational changes…A case control study from Sweden was published supporting an increased risk of pharyngeal cancers with exposure to welding fumes for longer than 8 years.”

Although he posited that caution must be used in extrapolating in terms of causation at a particular site, the specialist observed

“. . . it appears that the tumor arose in the oropharynx/tonsillar area – consistent with one of the locations deemed to be at risk in the study…”

On October 19, 2007, the panel met and made its final decision.

Reasons

Overview

Based on a balance of probabilities and considering the record as a whole, the panel finds that the worker’s cancer arising in the oropharynx/tonsillar area is an occupational disease particular to or characteristic to the worker’s trade of boilermaker/welder and not an ordinary disease of life. While the panel recognizes the etiology of the worker’s cancer may have been multi-factorial, it finds, based on a balance of probabilities, that the worker’s employment was the dominant cause of the disease.

Under subsection 1(1) of the Act, an occupational disease means a disease arising out of and in the course of employment and resulting from causes a) peculiar to or characteristic of a particular trade or occupation but does not include an ordinary disease of life or stress. Subsection 4(4) provides where a workplace injury consists of an occupational disease that is due in part to the employment of the worker and in part due to causes other than employment, the board may determine that the injury is a result of an accident arising out of and in the course of employment only where, the employment is the dominant cause of the occupational disease.

Board Policy 44.20 notes that in matters where it is argued that the employment of the worker has caused the disease, the concept of dominant cause is applicable and the claim must be adjudicated using “occupational disease criteria.” Under the policy, a disease will be described as characteristic of a particular trade, work process, or occupation if there is a preponderance of scientific evidence to support the conclusion that the nature of the work processes have significantly increased the likelihood of causing a particular disease in the workers who work in that trade or occupation. If the combined effect of the employment causes exceed the combined effect of non-employment causes then the work will be deemed to be the dominant cause of the disease.

Findings of Fact

The panel notes that the worker was employed as a boilermaker/welder at his workplace from the late 1970s to the early 1990s. The panel also notes that the worker’s job duties for at least 12 years (1979 – 1990) and perhaps longer involved welding. The panel concludes, based on a balance of probabilities, that while the worker’s duties between 1979 and the early 1990s always involved welding, there was an increased intensity in his welding duties dating from the early 1980s until the early 1990s. This was the time period in which he worked on locomotives or in the boiler shop and the panel finds, that it took place for at least eight years and likely more.

The panel notes that the recollection of the worker was challenged somewhat by the passage of time but finds the worker credible and considers his evidence in this proceeding to be supported by the evidence he gave in an earlier related proceeding.

The panel accepts the opinion of the independent specialist that it appears that the tumor arose in the oropharynx/tonsillar area.

The Scientific Evidence

The panel notes that the literature and scientific evidence in this area is evolving. It has carefully considered the scientific evidence available and the thoughtful reviews provided by the independent specialist. It accepts the conclusion of the occupational health physician that the study he referenced was most pertinent because it:

“Specified all included cancers of tonsils in their study population, analyzed pharyngeal cancers separately, reported specifically on welders as an occupational group and welding fumes as an exposure, studies duration of exposure to welding fumes, and had a reasonably large number of cases in welders. This study… supports the position that welding fume exposures can lead to cancers of the oropharynx. In this study prolonged, more than 8 years, welding fume exposure was associated with more than doubling of the risk of pharyngeal cancer.”

Considering the scientific evidence as a whole but relying in particular upon the above noted study, the panel concludes, based on a balance of probabilities, there is a preponderance of scientific evidence to support the conclusion that the nature of the work processes have significantly increased the likelihood of causing a particular disease in the workers who work in that trade or occupation.

The Dominant Cause of the Disease

The occupational health physician had no hesitation in ruling out factors such as smoking and drinking and concluding “welding exposures were the dominant cause of [the worker’s] development of cancer of the oropharynx.”

In examining the relationship between the worker’s cancer and his work, the independent specialist concluded “a causal relationship is probable but not certain”. In his view, the etiology of the worker’s carcinoma was likely multifactorial with about 50 percent being attributable to his work.

While the panel finds both opinions helpful to its conclusion, it places more weight on that of the occupational health physician because he more expressly considers risk factors such as alcohol or cigarette smoke.

The panel concurs, based on a balance of probabilities with the view of the occupational health physician, that it is unlikely that the worker’s cancer was related to any exposure to cigarette smoke or alcohol. While recognizing the potential that the etiology of the worker’s carcinoma was multifactorial, the panel finds, based on a balance of probabilities, that the worker’s employment was the dominant cause of the disease.

In making this finding on a balance of probabilities, the panel places particular reliance on:

  • the significant relationship identified in the study between the risk of pharyngeal cancer after more than eight years of exposure to welding fumes;

  • the development of the tumor in the worker’s pharynx;

  • the worker’s prolonged exposure to welding fumes for a period of at least 12 years; and

  • the lack of evidence supporting an etiology related to other known risk factors.

Conclusion

The panel finds, based on a balance of probabilities, that the claim is acceptable. Accordingly, the appeal is allowed.

Panel Members

B. Williams, Presiding Officer
R. Koslowsky, Commissioner
M. Day, Commissioner

Recording Secretary, B. Kosc

B. Williams - Presiding Officer

Signed at Winnipeg this 13th day of December, 2007

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