PBB homologs in sera of Michigan dairy farmers and Michigan chemical workers.

In November, 1976 the Environmental Sciences Laboratory of the Mount Sinai School of Medicine, examined 1029 persons in Michigan for the potential health effects of exposure to PBB. Included in this group were 55 persons from Michigan Chemical Corporation and 237 farming families. Blood serum was analyzed for PBB. FireMaster FF-1 contains several bromobiphenyl components, the major constituent being approximately 60% 2,4,4,2'4'4'-hexabromobiphenyl. Other PBB homologs identifiable as peaks by gas chromatography--mass spectrometry include two pentabromobiphenyl peaks, three additional hexabromobiphenyl peaks, and two heptabromobiphenyl peaks. The relative concentrations, with respect to the major hexabromobiphenyl peak, of these minor constituents (1--20%) of PBB were different for persons from Michigan Chemical Corporation and for farmers. Penta-, hexa-, and hepta-bromobiphenyl components in serum samples analyzed from farming families from Michigan Chemical Corporation employees were compared with relative concentrations of these homologs in FireMaster mixture and in tissue and blood samples from rats fed FireMaster FF-1. Varying concentrations of these PBB components are attributed to different routes of exposure and the relative ease of metabolism and excretion of one pentabromobiphenyl component.