Congener profile and toxicity assessment of polychlorinated biphenyls in human adipose tissue of Italians and Chileans

Human exposure to polychlorobiphenyls (PCBs) in humans was determined by analyzing adipose tissue samples collected in 1996–1997 from two different localities: Siena (Italy) and Concepción (Chile). ΣPCBs was higher in Italian samples than that from Chile (493 and 53 ng/g wet wt., respectively). Thirty-seven different PCB congeners were identified in all samples. The prevailing PCB congeners in both groups were 22′44′5 pentachlorobiphenyl (IUPAC no. PCB 118), 22′344′5′ (PCB-138) and 22′44′55′ (PCB-153) hexachlorobiphenyls and 22′33′44′5 (PCB-170), 22′344′55′ (PCB-180) and 22′34′55′6 (PCB-187) heptachlorobiphenyls. PCB-153 accounted for more than 20% of the total PCB residue in both groups, while the remaining six congeners accounted for approximately 70%. Hexachlorobiphenyls were the most abundant congeners in all samples, with 42% of total residue in those from Italy and 43% in the Chilean samples, followed by heptachlorobiphenyls with 41 and 36% in Italian and Chilean samples, respectively. Average concentrations of non-ortho substituted coplanar congeners were below 1 pg/g wet wt. In the samples from Siena no noticeable differences were observed between the three average coplanar concentrations, while in those from Concepción 33′44′tetrachlorobiphenyl (PCB-77) was much higher than 33′44′pentachlorobiphenyl (PCB-126) and 33′44′55′hexachlorobiphenyl (PCB-169). For each sample the contribution to the total toxic equivalent values (ΣTEQs) of each non-ortho, mono-ortho and di-ortho substituted PCB congeners was assessed. The overall TEQs calculated for the monitored PCBs, were 10.16 pg/g wet wt. in Italian samples and 1.09 pg/g wet wt. in Chileans ones. In both groups the main contribution to ΣTEQs were the di-ortho substituted PCB congeners (Siena: 6.17 pg/g wet wt.; Concepción: 0.56 pg/g wet wt.) and the mono-ortho substituted PCB congeners (Siena: 3.97 pg/g wet wt.; Concepción: 0.50 pg/g wet wt.).