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Heidi Michels Blanck,¹ Michele Marcus,² Vicki Hertzberg,³ Paige E. Tolbert,^2,4 Carol Rubin,⁵ Alden K. Henderson,⁵ and Rebecca H. Zhang³

¹Biological and Biomedical Sciences Division, Nutrition and Health Sciences Program, ²Department of Epidemiology, Rollins School of Public Health, ³Department of Biostatistics, Rollins School of Public Health, ⁴Department of Environmental and Occupational Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA; ⁵National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA

Abstract

Accidental contamination of the food chain in Michigan in 1973 with polybrominated biphenyls (PBBs) led to the establishment of a registry of exposed individuals in 1976. Serum was collected and analyzed for PBB at the time of enrollment and for targeted studies in the following years. We used the archived PBB data to study the elimination of PBB and to identify factors associated with elimination. A total of 380 women >= 16 years of age who had an initial PBB level of 2 ppb and at least two serum samples drawn when they were not pregnant were included in the analysis. The mean initial PBB level was 20.9 ppb (median 4) and mean time between the first and last measurement was 4.2 years (range 0.5-11.1) . PBB was assumed to reach equilibrium in the body before substantial amounts were eliminated and before the first serum measurements were taken ; therefore, the entire body was modeled as a single compartment for PBB with exponential decay. Subject-specific decay rate estimates were regressed on predictor variables including initial age, body mass index (BMI) , smoking history, breast-feeding duration, and parity. In women with an initial PBB level < 10 ppb, the median half-life was 12.9 years ; in those with > 10 ppb, the median half-life was 28.7 years. Decay was significantly slower among women with an initial BMI at or above the median (BMI >= 23) . The calculated half-life values are estimates of decay and can be used to estimate body burden of PBB at various points in time other than at the time of serum collection. Key words: body mass index, decay, elimination, half-life, pharmacokinetics, polybrominated biphenyl. Environ Health Perspect 108:147-152 (2000) . [Online 6 January 2000]

http://ehpnet1.niehs.nih.gov/docs/2000/108p147-152blanck/ abstract.html

Address correspondence to M. Marcus, 1518 Clifton Road NE, Room 460, Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, GA 30322 USA. Telephone: (404) 727-8010. Fax: (404) 727-8737. E-mail: mmarcus@sph.emory.edu

We acknowledge the assistance and cooperation of the staff of the Michigan Department of Community Health. We also thank V. Burse, W. Zheng, and the staff of the Michigan Public Health Institute for their role in data collection.

This study was supported by grants R 825300-01-1 from the U.S. Environmental Protection Agency and RO1 ES08341-01 from the National Institute of Environmental Health Sciences. The Centers for Disease Control and Prevention provided funds for the maintenance of the PBB cohort.

Received 14 May 1999 ; accepted 2 September 1999.