Introduction Burden of cancer methods rely on estimates of the prevalence of exposure to relevant carcinogens.

Methods CAREX has been the primary source of information on the prevalence of occupational exposure to various carcinogens. CAREX reflects exposure in the early 1990s in Developed regions, particularly Western Europe. Information is based on industry. Separate information by gender and age is not available. The information reflects the prevalence of exposure - there is no information on level of exposure.

Results Advantages of CAREX for burden of diseases studies include that the study used sound methodology; covered most countries in Western Europe and included some data from North America; the information has already been collected; and the time period covered is appropriate given latency considerations.

Use of CAREX for burden estimates also raises significant challenges, particularly in developing countries. In terms of geographic variation, the information was not collected from Developing countries and there are few data to indicate the extent to which the prevalence (and level) of exposure is similar for the same type of industry in different countries. In the Global Burden of Disease study, attempts to address these issues have involved using the same CAREX prevalence for all regions but adjusting the relative proportion of people exposed to ‘High’ levels of exposure and ‘Low” levels of exposure. This approach has merit but there are limited data in the literature to guide the relative proportions that should be used. General issues include that exposure is likely to be more homogenous within an occupation rather than an industry; and exposures are probably more common/higher for males compared to females within the same industry.

Discussion and conclusion Improvements in the estimates of the prevalence and level of exposure to occupational carcinogens would usefully contribute to improvements in burden of disease estimates.