The State of Michigan has a long history of research into human exposure to environmental contaminants through consumption of recreationally caught fish. A large cohort of Lake Michigan residents who eat fish (fish-eaters) and those who do not eat fish (nonfish-eaters) established in 1980 served as the basis for the congener-specific polychlorinated biphenyl (PCB) exposure evaluation reported here. In this paper we present the serum PCB congener profile for a subset of this cohort who were over 50 years of age. Serum samples were collected in 1993-1995 and were evaluated by a dual column capillary column gas chromatography procedure capable of detecting over 90 PCB conners. This evaluation demonstrated significant PCB exposure in the fish-eaters (mean serum PC-Iof 14.26 ppb; n = 101). This elevated exposure allowed the establishment of a detail profile ofthe PCB congeners found in humans exposed by this route. Twenty-two congeners of varying concentrations were the most prevalent and constituted over 95% of the total PCB present in most subjects. Four congeners, 1381163 (2,2',3,4,4',5-PCB/2,3,3',4',5,6-PCB), 180. (2,2',3,4,4',5,5'-PCB), and 153 (2,2',4,4',5,5'-PCB), accounted for 55-64% of the total PCBload. Other congeners, some of toxicologic significance, were also detected by this analytical protocol. Nonfish-eaters had lower total serum PCB levels (mean = 4.56; n = 78), but the same general pattern-ofPCB congeners was present. It was demonstrated that carefil selection of a subset of prevalet PCB congeners could provide a cost-efTective assessment of exposure without losing critical scientific information. Key words: aging, capillary column gas chromatography, fish-eaters, Great Lakes, Lake Michigan, polychlorinated biphenyl (PCB) congener profile. [1979][1980][1981][1982] (1,2). This cohort was unique because of its size (572 fish-eaters and 419 controls), age stratification (18-79 years), elevated fish consumption (24-270 lb/year; median 38.5 lb/year), and era of recruitment (10-20 ppm DDT and PCB levels in trout and salmon). Reported serum levels, based on packed column analytical methodology, showed significant PCB exposure in fish-eaters (median 21.4 ppb) as compared to control subjects who ate little or no sport-caught fish (median 6.6 ppb) (1,2). This confirmed earlier pilot work which indicated that contaminated fish represented the most significant route of PCB exposure for humans and that age, duration of consumption, and amount consumed correlated with exposure (3). Retesting of a portion of this cohort in 1989 showed no significant decline in average serum PCB levels (4). In contrast, fish-eaters recruited more recently have been found to have serum PCB levels far below those in the Michigan cohort (5-7). Although the Michigan cohort does appear to be more highly exposed than other more recently recruited cohorts, it is difficult to make direct comparisons between older studies in which PCBs were determined via packed column chromatography and more recent studies in which PCBs were quantitated...
