The long-term health effects of human exposure to
polybrominated biphenyls are not known. In this nested case-control study, we evaluated the association between site-specific
cancer risk and serum polybrominated
biphenyl levels among a Michigan cohort accidentally exposed to
polybrominated biphenyls in 1973. The Michigan Department of Public Health has followed 3,899 people through 1993, among whom 195 primary
cancers were identified in 187 persons. Controls were 696 randomly selected
cancer-free individuals who were frequency matched to cases by sex and age (in 5-year strata). Baseline serum polybrominated
biphenyl levels were measured using standard methods. We found an increasing dose-response relation for
digestive system cancer risk with higher serum polybrominated
biphenyl category [4-20 parts per billion (ppb), 21-50 ppb, and > 50 ppb] after adjustment for age, family
cancer history, cigarette smoking, alcohol drinking, and baseline serum
polychlorinated biphenyl level. Adjusted odds ratios (
ORs) for each category were 8.23 [95% confidence interval (CI) = 1.27-53.3], 12.3 (95% CI = 0.80-191), and 22.9 (95% CI = 1.34-392), respectively. Univariate analysis for polybrominated
biphenyl level and
lymphoma risk also showed a dose-response relation, with corresponding
ORs of 3.24 (95% CI = 0.24-95.9), 20.5 (95% CI = 1.51-608), and 32.6 (95% CI = 3.33-861).