WORKPLACE SAFETY AND INSURANCE BOARD
APPEALS RESOLUTION OFFICER DECISION
DECISION NUMBER: 20110024
OBJECTION BY: Worker
DATE: October 27, 2011
PARTICIPANTS: Worker, Worker Representative
ISSUE
The worker claimed entitlement for large B-cell lymphoma (non-Hodgkin lymphoma) as causally related to his employment exposures between 1980 and 2000.
HOW THE ISSUE ARISES
The claim was submitted to the Workplace Safety and Insurance Board (WSIB) for the worker’s non-Hodgkin lymphoma (NHL) which was diagnosed in 2007.
The worker claimed that, in particular, his exposure to benzene during his occupation as an Electrician/Instrumentation Mechanic between 1980 and 2007 was a significant contributing factor to the development of his disease.
The worker claimed that his exposure to benzene was more probably than not the cause of his condition.
The claim was adjudicated and, with the assistance of the WSIB’s Occupational Hygiene Exposure Review as well as an opinion from the WSIB’s Occupational Medicine Consultant, entitlement was denied on the basis that the evidence did not establish that the worker’s exposure to benzene was a significant contributing factor to the development of the disease.
AUTHORITY
Workplace Safety and Insurance Act (the Act) Section 2(1) and Section 15.
ASSESSMENT OF THE EVIDENCE
The worker confirmed his employment history and his exposure to benzene and other chemicals, as documented in the claim file. In particular, the worker provided testimony with respect to his benzene exposure.
The worker testified as follows:
His job was to check instruments to ensure that the valves and gauges were functioning. On occasion, there would be residual chemicals in the lines, which housed the instruments.
The worker testified that in his earlier years of employment, personal protective equipment was not used. However, they have always been available in the warehouse.
He recalled one occasion, some 12 to 15 years ago, when he was exposed to a sudden blast of benzene. He had to leave the area, sat down and then felt okay enough to return to work.
In December 2000, a major leak occurred when he was not at work. This apparently occurred a few days before he returned to work on the Monday. He noted that the readings on the Monday were 0.2-2 ppm and he had to wear a half mask and later a full mask.
The worker stated that in the early years of his employment, the employer did provide information with respect to the dangers of the various chemicals onsite. He was never required to do any cleanup of any spills and personal protective equipment was always available as he had one at his desk, which he did wear on occasions (some 25 per cent of the time) whenever he worked on lines known to contain benzene.
When removing instruments from the lines, this occurred outdoors, he always stayed upwind of the transmitter so that it would reduce the amount of fumes that he was exposed to.
The worker stated that on numerous occasions he was exposed to benzene while working downwind of others who were working on removing instruments.
Since 1980, the employer has placed him in the Benzene Surveillance Program. This required a yearly physical examination and urine and blood tests. He was never advised of any unusual findings other than on some occasions that he had elevated liver enzymes.
On a daily basis, he worked four to six hours on average outdoors and two to four hours indoors (he worked an eight hour day).
Since 1998, there has been a focus on health and safety, when a union became active at the employer.
With respect to his benzene exposure, the worker testified that this would not have occurred on a daily basis and sometimes not even weekly. He noted that there were times when he had to work in areas away from production, as an example, in one of the five electrical sub-stations, the office, cooling tower or control room. Therefore, he was not exposed to benzene on a daily basis.
When considering the testimony of the worker I note that his exposure history, as testified, is consistent with the WSIB Occupational Hygiene Review. The WSIB Occupational Hygienist noted that spills of benzene at the production area occurred. However, it is difficult to estimate the frequency/duration that the claimant spent on handling devices/instruments containing benzene or with benzene residue inside. It was noted that a review of the history of benzene monitoring data suggests that benzene exposure could be above 0.5 ppm during servicing activities of benzene units in the petroleum industry. Therefore, it is reasonable to assume that the worker could have experienced occasional, periodic exposures over approximately 30 years, to benzene, in excess of the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) of 0.5 ppm during servicing activities of instruments that originate from benzene pipelines. In addition, the employee’s daily exposure to benzene is anticipated to have been below the occupational exposure limit based on his personal hygiene monitoring results.
I also note the conclusion of the WSIB’s decision maker, that the evidence as reviewed by the WSIB’s Medical Occupational Disease Policy Branch (memo 33) concluded:
“There is limited evidence of an increased risk of NHL after exposure to benzene. There is evidence that the overall risks associated with chronic exposure to benzene increase slightly with the level of exposure. There is limited scientific information, however, regarding the amount of benzene exposure needed to result in an increased risk of NHL.”
It was concluded that, noting the worker’s daily exposure which was anticipated to be below the TLV, entitlement will remain denied.
I also note the opinion of the WSIB’s Occupational Medicine Consultant as documented in memo 24. The doctor noted: “I would agree that there is a reported association between benzene exposure and large B-cell lymphoma…”
Since the opinion of the WSIB’s Medical Consultant, additional research has been conducted with respect to a relationship between benzene and NHL.
In particular, I am aware of a number of WSIAT decisions which have denied entitlement for NHL and exposure to benzene. In particular, Decision 1098-11, Decision 855-10 and most recently, Decision 219-11.
In Decision 219-11, the worker’s employment was similar to that of this worker. Between 1959 and 1996, it was accepted that the worker’s jobs exposed him to petroleum products, including benzene, on a regular and consistent basis with the actual exposure levels unknown.
In Decision 219-11, the opinion of an Occupational Medicine Consultant was obtained as a tribunal assessor. Dr. Saary was chosen and a literature review was conducted. The doctor noted that in the case 219-11, the worker also suffered with a B-cell lymphoma. Dr. Saary noted in paragraph 12:
“Taking the above into consideration, of all the papers I examined, the following 46 page report from 2010 provides a detailed overall assessment of the current knowledge of an association between benzene and NHL. A copy of this paper accompanies this submission.”
The paper referenced by Dr. Saary is titled “A Historical Review and Appraisal of Association with Various Diseases”, by D. Galbraith, S. Gross, S. Paustenbach, published in Critical Reviews in Toxicology (2010); 40(S2); 1-46. It is noted that the article considers over 300 published reports on the topic as well as documents published by a number of government agencies. Dr. Saary states:
“ The article explains the effects of advances in immunology and histopathology for reorganizing classification strategies for lymphoma, with a goal of better selecting treatments because previous classification systems correlated poorly with prognosis. ...
Conclusion:
“In summary, there is general agreement that benzene exposure, in high concentrations over many years, leads to an elevated risk for [acute myelogenous leukemia]”.
“Although there have been reports of disease associations with other forms of leukemia, as well as with lymphomas and multiple myeloma, the overall evidence to date has been spotty and does not indicate a consistent causal relationship”.
“The only malignant hematopoietic disease that has been clearly linked to benzene exposure is [acute myelogenous leukemia]”.
[Dr. Saary’s emphasis].”
In paragraph 15 of the decision, Dr. Saary also identifies a recent article published by the International Agencies for Research on Cancer, which reviewed over 100 articles relating to benzene and found that evidence for a linkage with NHL was “deemed limited”.
In paragraph 16, Dr. Saary answered the question of whether the state of the current medical knowledge and research supports an association between exposure to petroleum products and/or benzene and the development of NHL. The doctor stated:
“Although there is well-documented risk for the development of [acute myelogenous leukemia] with benzene exposure, the available data on the association between benzene and NHL is less clear. Many authors acknowledge that a link between benzene and NHL is plausible. Although there is mounting evidence of association, the current state of the literature does not allow the clear establishment of a causal relationship because of limitations with the available data. As more studies are undertaken to address these limitations, I would expect better understanding of the nature of emerging relationship between benzene and NHL. .”
With respect to the causes of NHL, Dr. Saary noted they were:
Advanced age;
Male gender;
Family history of NHL;
Personal history of cancer;
Immune deficiencies or immunosuppressive agents;
Infectious agents such as Epstein-Barr virus, HIV;
Pesticides.
It is noted that the first two risk factors are present. There is insufficient information to comment on the others.
In the case reviewed by Dr. Saary, there are many similarities with this worker. These include:
The level of exposure was most likely low level but chronic, although this is not based on quantifiable data. In Mr. Munroe’s case, the quantifiable, available data indicates that the worker did not have exposures above the TLV for benzene.
The bloodwork results during the time that the worker has been in the Benzene Surveillance Programs have never showed any elevated exposure levels or health-related changes, related to such exposure.
The weight of the evidence does not support that the worker’s NHL condition can reasonably be attributed to his workplace exposures. The current state of the medical and scientific evidence does not support a work relationship between benzene exposure and NHL. The test of entitlement is one of significant contribution and that has not been established in this case.
As noted by the decision maker in Decision 219-11, the WSIB Occupational Disease Policy and Research branch conducted a detailed study of occupational factors for an increased risk of NHL. Certain occupations had an increased risk, but not petroleum workers and not workers who had exposure to petroleum-derived liquids and combustion products such as cutting fluids, aviation gas and gasoline.
As noted by the decision maker under Decision 219-11, Dr. Saary conducted an extensive literature review and concluded that the state of the medical research at this time is not sufficient to establish a causal relationship. This is consistent with the findings of the WSIB Occupational Disease Policy and Research branch.
CONCLUSION
The weight of the evidence does not establish a causal relationship between the worker’s employment exposure to benzene and the development of his NHL. No evidence is presented that any other occupational factors or exposures were significant contributing factors in the development of the worker’s NHL.
The worker’s objection is denied.
DATED December 8, 2011
N. Kissoore
Appeals Resolution Officer
Appeals Branch