Geographic variation of chlorinated pesticides, toxaphenes and PCBs in human milk from sub-arctic and arctic locations in Russia

The concentrations of HCB, α-, β- and γ-HCH, 3 chlordanes (CHLs), p,p′-DDE, p,p′-DDD, p,p′-DDT, and 30 PCBs (polychlorinated biphenyls) were determined in 140 human milk samples from Kargopol (n=19), Severodvinsk (n=50), Arkhangelsk (n=51) and Naryan-Mar (n=20). Pooled samples were used for determination of three toxaphenes (chlorobornanes, CHBs). The concentrations of HCB, β-HCH and p,p′-DDE in Russian human milk were 2, 10 and 3 times higher than corresponding levels in Norway, respectively, while concentrations of sum-PCBs and sum-TEQs (toxic equivalent quantities) of the mono-ortho substituted PCBs were in the same range as corresponding levels in Norway. The PCB-156 contributed most to the sum-TEQs. Highest mean concentrations of HCB (129 μg/kg milk fat) and sum-PCBs (458 μg/kg milk fat) were detected in Naryan-Mar, while highest mean concentrations of sum-HCHs (408 μg/kg milk fat), sum-CHLs (48 μg/kg milk fat), sum-DDTs (1392 μg/kg milk fat) and sum-toxaphenes (13 μg/kg milk fat) were detected in Arkhangelsk. An eastward geographic trend of increasing ratios of α/β-HCH, γ/β-HCH, p,p′-DDT/p,p′-DDE and PCB-180/28 was observed. In all areas the levels of sum-HCHs decreased with parity (number of children born). Considerable variation in levels of the analysed organochlorines (OCs) was found in all the studied areas. Breast milk from mothers nursing their second or third child (multiparas) in Naryan-Mar showed a significant different PCB profile compared to mothers giving birth to their first child (primiparas) from the same area and to primi- and multiparas in the other areas. Both p,p′-DDE and p,p′-DDT showed a significant, but weak, negative correlation with the infants birth weight.