Critical literature review of determinants and levels of occupational benzene exposure for United States community-based case-control studies.

This article presents the results of an extensive literature review identifying the uses or occurrences of, and exposures to, benzene in a variety of industries for a community-based case-control study of childhood brain cancer in the United States and Canada. We focused on industries for which quantitative exposure data were identified in studies conducted in North America in the 1980s. Each industry was coded according to the 1987 Standard Industrial Classification (SIC) system. For each industry, information relevant to exposure assessment, including process descriptions, job titles, tasks, and work practices, was summarized when available. Estimates of probability and intensity of exposure, and our confidence in these estimates are presented. Arithmetic means (AMs), weighted for the number of measurements for each industry, were calculated based on measurement data from long-term (i.e., 60+ minutes) personal sampling; short-term or area samples were only used when no other data were available for a given industry. Industries for which no quantitative exposure levels were identified in the North American literature but for which information was found on benzene use are briefly described. Published exposure data indicate that workers in most industries in the 1980s experienced exposure levels below the current standard of 1 part per million (ppm), with a weighted AM of 0.33 ppm across all industries. Despite the longtime recognition of the hematological effects of benzene, little information was available on exposure levels and determinants for many industries with potential exposure. Nevertheless, this review may clarify some of the procedures involved in assessing occupational exposures in community-based studies and may aid in the interpretation of previous occupational studies that relied on job title or industry.