WORKPLACE SAFETY AND INSURANCE APPEALS TRIBUNAL DECISION NO. 2381/10

Transcription

1 WORKPLACE SAFETY AND INSURANCE APPEALS TRIBUNAL DECISION NO. 2381/10 BEFORE: S. Martel : Vice-Chair A.D.G. Purdy : Member Representative of Employers M. Ferrari : Member Representative of Workers HEARING: November 30, 2010 at Kitchener Oral DATE OF DECISION: January 21, 2011 NEUTRAL CITATION: 2011 ONWSIAT 171 DECISION UNDER APPEAL: WSIB Appeals Resolution Officer (ARO) decision dated July 28, 2009 APPEARANCES: For the worker: For the employer: Interpreter: L. Horne, Office of the Worker Adviser Did not participate N/A 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 7 th Floor 505, avenue University, 7 e étage Toronto ON M5G 2P2 Toronto ON M5G 2P2

2 Decision No. 2381/10 REASONS (i) Introduction [1] The worker s estate appeals the ARO decision dated July 28, 2009, which found that the worker s lung cancer was not causally related to his employment with a tire manufacturer. The worker s estate submits that the worker s employment in various job functions with the tire manufacturer from 1966 to 1991 significantly contributed to his lung cancer diagnosed in The worker unfortunately passed away as a result of lung cancer on October 28, [2] The worker s spouse and daughter attended the hearing and testified. Ms. Horne made submissions. We also considered six documents entered as exhibits. (ii) Background [3] The worker s estate filed a claim with the Board in 2002 as part of a cluster of rubber industry claims. The worker worked for a tire manufacturer in various positions from September 1966 to December 1992, although he was on a leave of absence for illness reasons the last year of his employment. The worker was diagnosed with cancer in 1992 and died on October 28, 1993 at the age of 62. The autopsy revealed a large bronchogenic adenocarcinoma of the right lung that had metastasized. [4] The Board conducted extensive investigations in this claim including obtaining an occupational hygienist exposure assessment and a scientific review of cancer in the rubber industry from the Board s Medical and Occupational Disease Policy ( MODP ) Branch. The worker had a significant smoking history and the Claims Adjudicator and the ARO ultimately denied the worker s claim. The estate now appeals to the Tribunal. While the estate admits that the worker s smoking history likely contributed to his lung cancer, it submits that the worker s occupational exposure to various substances, notably nitrosamines, also significantly contributed to his lung cancer. (iii) Employment history [5] The worker was hired by the tire manufacturer in September 1966 and retired on December 16, He worked at the tire plant or the rubber machinery shop ( RMS ) as follows: September 19, 1966 to October 13, 1970: janitor and stores, RMS October 13, 1970 to March 6, 1972: salvage helper, salvage March 6, 1972 to June 9, 1975: RMS June 9, 1975 to April 19, 1988: tire builder, passenger tire building April 19, 1988 to June 20, 1988: leave of absence (cataract surgery) June 20, 1988 to February 6, 1989: salvage wire belts, passenger tire building February 5, 1989 to April 17, 1989: leave of absence (cataract surgery for the other eye) April 17, 1989 to December 16, 1991: salvage wire belts, passenger tire building December 16, 1991 December 16, 1992: leave of absence.

3 Page: 2 Decision No. 2381/10 (iv) Smoking history [6] Both the worker s spouse and daughter testified about the worker s smoking. The spouse testified that the worker smoked perhaps half a pack per day although she admitted that she was unsure. She also admitted that the worker smoked in the house. The worker s daughter thought that the worker smoked five to six cigarettes per day although she admitted that she was not always around and also knew that her father smoked during break times at work. She testified that the worker quit cold turkey around [7] Medical information from Dr. Dingle and Dr. Sharkey, who both treated the worker for his cancer, states that the worker smoked one pack per day for 40 years. We note that the worker saw Dr. Smith, a specialist in allergies, in February 1979 and at that time indicated that he smoked about one pack per day. [8] Given that the worker s spouse and daughter were not constantly around the worker in order to know how much he smoked, we prefer the information found in the medical records, which likely originated from the worker himself. We also prefer the information found in the medical records because it was given before a claim was initiated with the Board and prior to the worker s estate trying to establish a link between the worker s cancer and workplace exposures. The information found in the medical reports is, in our view, more objective and reliable. Accordingly, we find that the worker smoked approximately one pack per day for 40 years until he quit in [9] The Tribunal Discussion Paper entitled Evidence for Smoking Causing Lung Cancer dated June 2008 and prepared by Dr. Jones was part of the case materials in this appeal. The paper states that tobacco accounts for over 80% of lung cancers and that the risk increases exponentially with length of time smoked. In the case of a former smoker, the risk declines gradually but takes 15 years before reaching its maximum. The worker had only quit for approximately three years when he was diagnosed with cancer. [10] The scientific review document prepared by the MODP Branch on cancer in the rubber industry, dated February 3, 2005, also discusses the causal link between lung cancer and smoking. As with the Tribunal s Discussion Paper, this paper states that the major cause of lung cancer in both sexes is cigarette smoking, accounting for at least 80% of all new cases in women and 90% of those in men (Health Canada 2005). The average relative risk of smokers compared to non-smokers is approximately ten and the relative risks for heavier smokers who smoked for many years are higher. Smoking cessation causes relative risks to decline towards that of nonsmokers; however, even for periods of abstinence of greater than 40 years, the risk of lung cancer among former smokers remains elevated compared to non-smokers (Alberg and Samet, 2003). [11] The worker s estate admitted that the worker s smoking history significantly contributed to his lung cancer. They submitted, however, that smoking was not the only factor. We find that the smoking history in this case is a very significant contributing factor to the worker s cancer. In the following subsections, we will address whether the worker s employment exposures were also a significant contributing factor.

4 Page: 3 Decision No. 2381/10 (v) Medical diagnosis [12] When the worker was first diagnosed with cancer, there was some initial question regarding the exact type of cancer he had as well as where it originated. Towards the end of his life, however, the medical records consistently referred to bronchogenic cancer of the lung. An autopsy was done and it confirmed that the worker had an adenocarcinoma of the lung as a primary cancer, which had metastasized. We accept the diagnosis of primary adenocarcinoma of the lung. (vi) Occupational hygiene assessment [13] Mr. D. Chung, a Board Occupational Hygienist, was asked to assess the worker s potential exposures to workplace agents, focusing on nitrosamines, asbestos and polycyclic aromatic hydrocarbons ( PAH ). Mr. Chung noted that the facility where the worker worked manufactured rubber tires for passenger cars, trucks, inner tubes and flaps. The production processes were typical of tire manufacturing and included compounding, mixing, stock preparation, building, curing, finishing and warehousing. Mr. Chung provided the following summary of the worker s exposures: Exposure Agent Work Area (year) Pattern of Duration Exposure Exposure A Ranking Level of Confidence D Nitrosamines Asbestos PAHs RMS (non-production) ( & 72 75) Tire Building ( & 75-91) RMS (non-production) ( & 72-75) Tire Building ( & 75-91) RMS (non-production) ( & 72 75) Tire Building ( & 75-91) Rare 7.3 yr. High B Low Routine 17.5 yr. High B Low Routine 7.3 yr. Low C Low Routine 17.5 yr. Low C Moderate Rare 7.3 yr. Low B Low Routine 17.5 yr. Low B Low A Pattern of Exposure: The pattern of the exposure is defined as: routine if the task was conducted on daily basis or if the worker spent >50% of the work shift potentially exposed to the agent; occasional if the task occurred on a weekly/monthly basis or if the worker spent 50-25% of the work shift potentially exposed, and rare if the task was unplanned or if the worker was potentially exposed for <25% of the shift. B Chance of Exposure: In this report Chance of Exposure is defined as a qualitative descriptor of exposure that considers the frequency and the likelihood that the worker came into contact with the exposure agent. This descriptor is typically used to assess exposures that do not lend themselves to quantitative assessments or where adequate air monitoring data are unavailable.

5 Page: 4 Decision No. 2381/10 C Intensity of Exposure: The level of exposure is defined as high if it was likely that the airborne concentrations exceed 50% of the current occupational exposure limit. A low level is defined as concentrations below 10% of the OEL and a moderate level is between a high and a low level. 7 A review of the TLV documentation for asbestos (2005 TLV - TWA is 0.1 f/cc) indicated that the TLV was based on minimising the potential for developing of asbestosis and lung cancer. The TLV for coal tar pitch volatiles (2005 TLV-TWA of 0.2 mg/m 3, as benzene solubles) is intended to minimize the potential for an increase in the incidence of lung and other tumors. The TLV documentation for carbon black (2005 TLV-TWA of 3.5 mg/m 3 ) indicated that the TLV is intended to minimize complaints of excessive dirtiness. The recommended TLV applies only to commercially produced carbon blacks; soots derived from combustion sources containing absorbed polycyclic aromatic hydrocarbons are excluded. D Level of Confidence: The ranking of the level of confidence associated with each exposure estimate is defined as: low if the exposure estimates were based primarily on qualitative factors. moderate if a combination of qualitative factors and inferential air sampling data high if the exposure estimates were based on appropriate air sampling data. 7 Mulhausen, J.R. and Damiano, J.): A Strategy for Assessing and Managing Occupational Exposures, Second Edition, American Industrial Hygiene Association Exposure Assessment Strategies Committee, Fairfax, VA: pg. 64 (1998) [14] Ms. Horne also provided a document from the Encyclopedia of Occupational Health and Safety, 4 th Edition, which includes a process description summary of the plant where the worker worked. Ms. Horne submitted this document as evidence that the worker was exposed not just to nitrosamines, asbestos and PAH, but also to many other toxins such as benzene and other solvents. This document notes that in some plants, the majority of the particulate is carbon black. Between July 1972 and January 1977, OSHA conducted 85 surveys of carbon black exposures to determine compliance with the occupational limit of 3.5 mg/m 3. Approximately 20% of inspected workplaces were in violation of the standard and levels in about 60% of these were one to two times above the standard (International Agency for Research on Cancer IARC, 1982). The document notes that the processes are generally quite dusty and that local exhaust ventilation is rarely found at tire building operations. This creates potential sources of exposures to solvents through the air and via the skin. (vii) Scientific evidence [15] The case materials refer to two main external sources that reviewed the literature on cancer in the rubber industry. These are discussed in the MODP Scientific Review of Cancer in the Rubber Industry dated February 3, [16] IARC reviewed the literature on cancer in the rubber industry in 1982 focusing mainly on studies conducted in the tire manufacturing and repair sector, the cable-making sector and the manufacture of other rubber goods. IARC s findings were based on studies conducted in Britain and the United States. British studies in the tire and non-tire sectors reported excess mortality from lung cancer. In the U.S., cases of lung cancer were linked with work in compounding and mixing, extrusion, curing, rubber reclaim and fuel cell and de-icer manufacture. The following table summarizes IARC s 1982 conclusions with respect to various cancers:

6 Page: 5 Decision No. 2381/10 Strength of Evidence Sufficient for excess occurrence in rubber workers & for causal association with occupational exposures Sufficient for excess occurrence in rubber workers & limited for causal association with occupational exposures Limited for excess occurrence in rubber workers & for causal association with occupational exposures Limited for excess occurrence in rubber workers & inadequate for causal association with occupational exposures Inadequate for excess occurrence in rubber workers & for causal association with occupational exposures Type of Cancer Bladder Leukemia Stomach Lung Skin Colon, Prostrate Lymphoma Brain, Thyroid Pancreas, Esophagus [17] To re-evaluate and update their earlier conclusions, IARC re-examined the literature regarding the carcinogenicity of the rubber industry in A large number of studies had then been conducted in the rubber industry worldwide in Canada, China, Finland, Norway, Sweden, Switzerland, the United Kingdom and the U.S. With respect to lung cancer, the report concluded that there were excess cancers in various product areas and departments but that the reports were not consistent. IARC s overall evaluation was that working in the rubber industry entails exposures that are carcinogenic to humans. [18] Another comprehensive review was done in 1998: Cancer risk in the rubber industry, A review of the recent epidemiological evidence (Kogevinas et al., 1998). This review examined the epidemiological studies published after the review by IARC in 1982 and up to Kogevinas et al. focused on the same sectors of the rubber industry as IARC including tire manufacturing and repair, cable making and manufacture of other rubber goods. The review included 12 cohort studies in nine countries, seven industry based nested case-control studies, 48 community based case-control studies in 16 countries and 23 surveyance studies that reported risks for working in the rubber industry. Kogevinas et al. found that most studies reported excess risks for bladder cancer, lung cancer and leukemia, with risks above 1.5 in half of the studies, supporting IARC s conclusions. These studies did not provide information about the association risk with specific exposure agents. [19] The purpose of the Board s MODP review was to summarize the epidemiologic evidence published since the most recent evaluation, which was completed by Kogevinas et al. in With respect to lung cancer, the scientific review reported: Lung Cancer Of three cohort studies that had investigated mortality risks in males, the study suffering from the least number of methodological limitations reported the number of observed deaths as significantly greater than expected for males in the rubber industry (SMR 123). Two cohort studies of lesser quality reported lung cancer mortality risks less than expected, with one of the estimates reaching statistical significance. The rate of incident cancers in one cohort was not elevated. Three cohort studies had investigated lung cancer mortality among female rubber workers. One cohort reported a mortality risk less than expected, while another cohort did

7 Page: 6 Decision No. 2381/10 not observe any lung cancer deaths. A third cohort reported an elevated mortality risk of 140, which lacked statistical significance. No dose response trends of increasing risk with increasing exposure were evident in these cohort studies. Of six case-control studies, five were hospital or study centre-based, a study design best used for screening hypotheses regarding occupational exposures. For males, two hospitalbased studies reported elevated odds ratios of two- and three-fold, and one study reported an odds ratio of less than unity. For females, three hospital- and one study centre-based case-control studies reported elevated odds ratios greater than 2.0 (range 2.4 to 5.6). The single, more informative case-cohort study reported evidence of a dose-response trend of increasing risk of lung cancer with increasing duration of exposure in the tire-curing department. Estimates in this case-cohort study were adjusted for smoking. Overall, the evidence from the more methodologically sound studies suggests increased risks over the different study designs. In summary, the limited scientific evidence published since 1996 suggests a low to moderate excess risk of lung cancer in rubber workers. Sub-group analysis by work area included evidence for an association between excess mortality and employment in the early production stages. A cohort study reported a statistically significant increased mortality risk for those who worked more than 10 years and/or who were hired in 1960 or later in the preparation area, specifically in the area of weighing and mixing. An elevated mortality risk was also reported for those who worked more than 10 years in the area of milling and calendaring. These findings for the preparation stage are congruent with the conclusions from the previous reviews; however, IARC had also reported cases of lung cancer linked to the curing and rubber reclaim departments of the Akron, Ohio cohort. The review by Kogevinas et al. (1998) had also reported elevated risks for the vulcanization departments. One cohort study reported that exposure to nitrosamines was not associated with lung cancer mortality, but an increased dose-response relationship was observed between asbestos/talc exposure and lung cancer. In 1982, IARC had found sufficient evidence for an excess occurrence of lung cancer in rubber workers, and in 1998, Kogevinas et al. had reported a consistent moderate excess risk in rubber industry cohorts and sub-groups. The current review found limited evidence of a low to moderate excess risk of lung cancer in the epidemiological literature published since Two of the cohort studies in the current review conducted subgroup analysis, but one study had many methodological limitations, so statements about excess risks for lung cancer in specific departments of the rubber industry are not conclusive. Generalizations about duration of employment are also difficult because the length of follow-up ranged among the studies. In conclusion, the entire body of evidence suggests a moderate excess risk of lung cancer for employment in the rubber industry. [Emphasis added] [20] The overall conclusion of the MODP review for all cancers studies was as follows: This systematic review found generally consistent evidence of an increased risk of bladder cancer, lung cancer and leukemia mortality for rubber workers. Only suggestive evidence was found for a low risk of stomach and laryngeal cancer. Some evidence of increased cancer risks were found for certain work areas in the rubber manufacturing process, such as an increased risk of bladder cancer for those who worked in the preparation of materials, or to specific occupational exposures, such as nitrosamines. However, there were too few studies, and the evidence was not conclusive. [21] The Panel agrees with Ms. Horne s submission that the last paragraph of the above-noted conclusion was misinterpreted by the ARO. As we read both paragraphs, MODP s review found

8 Page: 7 Decision No. 2381/10 generally consistent evidence of an increased risk of lung cancer mortality for rubber workers. What was not conclusive was whether this increased risk could be linked to a particular manufacturing process or a specific occupational exposure. Overall, however, rubber workers have an increased risk of lung cancer. [22] Dr. Pysklywec at the Occupational Health Clinics for Ontario Workers Inc. reviewed the worker's chart, the IARC and MODP reviews as well as the worker's work history. Dr. Pysklywec noted: The IARC reviews and the WSIB Scientific Review have been used to deny rubber claims of work-related cancers, such as esophageal, laryngeal and kidney cancer. This same information should be used to reasonably allow claims as well. The WSIB scientist suggested that there is adequate literature linking lung cancer, as well as bladder cancer and leukemia, to work in the rubber industry. However in considering [the worker's] claim, the adjudicator suggests, there were too few studies, and the evidence was not conclusive. A causa1 association between employment in tire manufacturing and the development of lung cancer can neither be identified nor ruled out. This conclusion seems inconsistent with the WSIB s Scientist s conclusion, whereby she is much less equivocal about her conclusions. Consideration of other factors The patient was reported to have a 40 pack-year history of smoking. This habit is known to be an independent risk factor for lung cancer. The relative contribution of smoking is always difficult to assess in occupationally exposed workers. As with most disease processes, it is likely that causation is multifactorial. Age is risk factor for most cancers. He was diagnosed with lung cancer at age 61. Conclusion: To summarize the medical evidence, [the worker] developed lung cancer in 1992 at the age of 61. He had spent 26 years in the rubber industry from 1966 to During his tenure, he had routine high exposure to nitrosamines from tire building. Despite his smoking it would be difficult to ignore the contribution of exposures in the rubber industry in causing his lung cancer. He had nearly two decades of heavy nitrosamine exposure as a tire builder. This group of chemicals is a known carcinogen. A WSIB review of cancer in the rubber industry implicates lung cancer, as well as bladder cancer and leukemia as having an association with these exposures. For these reasons, I conclude that his exposures in the rubber industry significantly contributed to causing his lung cancer. (viii) Conclusion [23] As can be seen from the above summary of the various scientific reviews, the IARC, Kogevinas et al. and MODP literature reviews done in 1982, 1998 and 2005 respectively, have all shown an increase of lung cancer risk in the rubber industry. The MODP review ultimately concluded that the entire body of evidence suggests a moderate excess risk of lung cancer for employment in the rubber industry. It is also clear that smoking increases the risk of lung cancer very significantly, accounting for at least 80% of all lung cancers. It is quite possible that the worker would have developed lung cancer independent of any workplace exposures. On the other hand, as opined by Dr. Pysklywec, it is impossible to rule out the likelihood that the worker's work exposures also contributed to his lung cancer.

9 Page: 8 Decision No. 2381/10 [24] The worker was a long time employee of a tire manufacturer and was exposed to various carcinogenic substances in that industry from 1966 to 1991, a period of 25 years, which is quite significant. During that 25 year period, the worker was exposed to known carcinogens, such as nitrosamines. The Board occupational hygienist indicated that the worker s nitrosamine exposure during his tire building years (17.5 years of his 25 year career with the accident employer) was of a routine nature. A routine pattern of exposure is when the worker spends more than 50% of his work shift potentially exposed to the agent. [25] As submitted by Ms. Horne, the test in occupational disease appeals is whether the workplace exposures were a significant contributing factor to the development of the worker's cancer on a balance of probabilities. As explained in a number of Tribunal decisions, including Decision No. 331/89 relied upon by Ms. Horne, the workplace exposures need not be the sole or most significant contributing factor but rather, a significant contributing factor. [26] Noting the length of the worker's employment, the routine exposures to known carcinogens and the literature reviews that suggest an overall moderate increase of lung cancer in the rubber industry, we find on a balance of probabilities that the workplace exposures in this case likely significantly contributed to the worker's lung cancer. Accordingly, we allow the appeal and find that the worker has entitlement for his lung cancer.

10 Page: 9 Decision No. 2381/10 DISPOSITION [27] The appeal is allowed. The workplace exposures significantly contributed to the worker s lung cancer. The worker has entitlement for his lung cancer. DATED: January 21, 2011 SIGNED: S. Martel, A.D.G. Purdy, M. Ferrari