Occupational cancer in Canada: what do we know?

To examine the reporting of cases of occupational cancer in Canada in order to determine reporting requirements, the availability of data, the characteristics of reported cancers and the completeness of reporting.

Descriptive epidemiologic study based on data requested from workers' compensation boards (WCBs) and cancer registries in each province and territory from 1980 to 1989.

The number of claims accepted and rejected by the WCBs; year of claim, cancer site, sex of claimant, age of claimant at diagnosis, occupation, industry, exposure agent and reasons for rejection of claims; and new primary cancers according to site, age and sex.

Reporting of occupational cancer by physicians is required in Alberta, Saskatchewan and Newfoundland. Only British Columbia, Saskatchewan and Ontario were able to provide all the requested information about the claims. Of the 1026 claims in these three provinces almost all were by men, and about two-thirds were for cancers of the respiratory tract. Asbestos was listed as the etiologic agent in more than one-third of the cases. A comparison of the proportion of incident cancers accepted as occupational by the WCBs with the estimated proportion of cancers in the general population attributable to occupation (based on population-attributable risk percentages from epidemiologic data) suggests that less than 10% of occupational cancers [corrected] are compensated. The main source of the deficit is underreporting to WCBs rather than rejection of claims.

The availability of data about occupational cancers in Canada is inconsistent from jurisdiction to jurisdiction, and reporting is incomplete. An active disease surveillance system and additional education of physicians and workers about work-related illnesses may be required to improve reporting.