A classification scheme for aggregating U.S. census occupation and industry codes.

The use of occupation as a surrogate for workplace exposures when more specific information is unavailable is common yet is particularly challenging in studies involving many diverse occupations. A classification scheme that aggregates workers based on similar job tasks and potential exposures was developed for use in a Canadian study, and its adaptation for a similar U.S. study is described. The 56 occupational categories and 1980 U.S. census occupation and industry codes used to create each are presented. The scheme was developed using the distribution of occupations and industries in two limited study populations, and no exposure measurements were taken in its preparation. However, the aggregation of jobs with similar exposures has practical utility in the analysis of a large number of specific occupations, each with a small number of workers. As a result, the scheme presented can provide a starting point for researchers facing this task in the analysis of case-control occupational data.