Highlights of Noteworthy Decisions

Decision 1861 10
E. Smith - M. Christie - D. Broadbent
  • Cancer (lung)
  • Evidence (epidemiological)
  • Exposure (silica)

The worker's estate appealed a decision of the Appeals Resolution Officer denying the worker entitlement for lung cancer.

The worker was a furnace operator from 1951 to 1972, and worked in the shake out area from 1972 to 1987. He was diagnosed with lung cancer in 1992 and died in 1993. The worker was exposed to silica, the most significant levels while working as the furnace operator from 1951 to 1972, but also in his work from 1972 to 1987. The worker had a 30 pack-year history of smoking. He did not have silicosis.
A medical report estimated the worker's increased risk of lung cancer from silica exposure. One estimate indicated a hazard ratio of 1.39 for a smoker with exposure to the high category of silica. Under this model, the percentage of cases in the group that was work-related was 28%. The other estimate resulted in a hazard ratio of 1.48, and a work-related percentage of 33%. The Panel did not find it necessary to prefer one model over the other. The Panel accepted that the data in that study suggested a finding in the range of 28% to 33% of the case.
The Panel noted the difference between use of a hazard ratio and use of relative risk analysis. Both measures are intended to summarize the comparison of the rate of events in a given population over time, but they differ in how they are calculated. A hazard ratio is based primarily on a time-to-event approach, and it may better account for events over time, a factor that may not always be as fully reflected in other risk analyses.
The finding that from 28% to 33% of cases of lung cancer identified in a cohort can be inferred to be work-related is not sufficient to form a basis for entitlement in the case of an individual worker, in the absence of probative evidence that the worker was at higher risk than the level of risk inferred from the epidemiological evidence. For it to be as probable as not that a worker's cancer is comparable to one of those that is work-related, there must be a 50% probability.
There is now evidence of some level of increased risk from silica exposure even for persons who have not been diagnosed with silicosis. This was previously in dispute. However, this did not affect the finding of the Panel that the identified risk was insufficient for entitlement.
The worker did not have entitlement for the lung cancer. The appeal was dismissed.