Cumulative exposure estimates for polychlorinated biphenyls using a job-exposure matrix

Abstract

PCB exposure has been associated with increased risk for cancer, neurological disease, and for birth defects in children exposed in utero. Because of the long half-lives of PCB congeners, they remain a public health problem in the United States 30 years after being banned. Workers ( n = 3569) at an Indiana capacitor manufacturing plant were exposed to polychlorinated biphenyls (PCBs) from 1957 to 1977. The purpose of this work was to develop a period-specific job-exposure matrix (JEM) for a follow-up epidemiologic study investigating the increased risks for cancer previously observed in the cohort. Methods: We used eight exposure determinants to estimate PCB exposures systematically. Work history, job description, capacitor production factors, PCB usage trends, and air sample data were used to develop the JEM in four steps: (1) all job titles ( n = 884) were assessed for exposure determinants, (2) jobs with similar exposure determinants were grouped, (3) for each job exposure category, exposure intensity (high–medium–low-background) and frequency (continuous–intermittent) were qualitatively rated separately for inhalation and dermal exposure, and (4) for each job exposure category, the product of intensity (based on air sampling data) and frequency (fraction of day exposed) was calculated. The JEM was then modified for two eras of different PCB exposure conditions. Results: The resulting JEM consists of inhalation and dermal exposure values for 19 job exposure categories. Conclusion: The JEM showed an exposure–response trend associated with increased brain cancer mortality in the epidemiologic study.