Human milk samples from 28 mothers at Oslo City Hospital, Norway, were collected in 1991 and analyzed for individual polychlorinated biphenyl (PCB) congeners, IUPAC numbers 28, 74, 99, 101, 105, 114, 118, 128, 138, 141, 153, 156, 157, 170, 180, 194, and 206, plus selected non-ortho-substituted compounds, IUPAC numbers 77, 126, and 169. Sum DDTs (sum of concentrations of DDT and related compounds), hexachlorobenzene (HCB), oxychlordane, transnonachlor, and sum hexachlorocyclohexanes (HCHs) (sum of concentrations of alpha-HCH, beta-HCH, and gamma-HCH) were also determined. The mean levels of sum DDTs, HCB, oxychlordane, transnonachlor, and sum HCHs were 338, 41, 9, 19, and 36 ng/g, respectively, in human milk fat. p,p'-DDE and beta-HCH accounted for 81 and 93% of sum DDTs and sum HCHs, respectively. The mean level of sum PCBs (sum of mean concentrations of 20 individual congeners) was 372 ng/g milk fat. A very good correlation was found between sum PCBs and PCB-153 (r = .97). Sum PCBs determined on a capillary column was found to account for 62-79% of total PCBs calculated by using the packed column method used in previous human milk surveys in Norway. Comparison with previous results revealed that the mean sum PCB, HCB and sum DDT levels were decreased by 70, 65, and 75%, respectively during the past 9 yr. The contribution of individual PCDD/PCDF (earlier Norwegian study) and non- and mono-ortho-substituted PCB congeners to the total calculated toxic equivalent values was assessed, and the PCBs were found to constitute a major part of the TCDD equivalents in human milk, with PCB-126 as the main contributor.
In 1993, 30 individual human milk samples were collected in Murmansk and Monchegorsk, and analysed for 23 polychlorinated biphenyl congeners, PCBs (IUPAC nos.) 28, 52, 66, 74, 99, 101, 105, 110, 114, 118, 128, 138, 141, 149, 153, 156, 157, 170, 180, 187, 194, 206, and 209. In addition, the following organochlorine pesticides (OCPs): hexachlorobenzene (HCB), the alpha-, beta-, gamma-isomers of hexachlorocyclohexane (HCH), the chlordanes: oxychlordane, trans-chlordane, cis-chlordane, trans-nonachlor, and cis-nonachlor, and the DDT-compounds: pp-DDE, pp-DDD, op-DDT and pp-DDT were detected. From each city, a pooled sample was made and analysed for non-ortho PCBs, dibenzodioxins (PCDDs) and dibenzofurans (PCDFs). In addition one individual sample from Monchegorsk was analysed for PCDDs/PCDFs because of the very high levels of PCBs in this sample. High levels of pp-DDE and beta-HCH were found in Murmansk and Monchegorsk (in parenthesis) with mean levels of 1269, (892) and 853, (739) micrograms/kg milk fat respectively. Highest individual levels of pp-DDE (2816 micrograms/kg milk fat) and beta-HCH (1988 micrograms/kg milk fat) were found in Murmansk. Significant differences were found between the levels of gamma-HCH, cis-chlordane, trans-nonachlor, cis-nonachlor, pp-DDE, and the PCBs 28, 52, 74, 66, 110, 118, 105, 128, 206, and 209, between the two areas. No geographic differences in the concentrations of PCDDs/PCDFs and non-ortho PCBs in the sample pools from the two Russian areas were observed.
The concentrations of HCB, alpha-, beta- and gamma-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, beta-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 microg/kg milk fat) and sum-PCBs (458 microg/kg milk fat) were detected in Naryan-Mar, while highest mean concentrations of sum-HCHs (408 microg/kg milk fat), sum-CHLs (48 microg/kg milk fat), sum-DDTs (1392 microg/kg milk fat) and sum-toxaphenes (13 microg/kg milk fat) were detected in Arkhangelsk. An eastward geographic trend of increasing ratios of alpha/beta-HCH, gamma/beta-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.
Concentrations of 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) as well as 16 polychlorinated biphenyls (PCBs) have been determined in pooled samples of breast milk from 10-12 mothers living in three different geographical areas in both Norway and Lithuania. The results indicate no apparent dependency of the PCDD/PCDF levels, expressed as toxic equivalents (TEQs), and total PCB levels on the geographical residence of the donors within a country. This confirms the findings from a corresponding Norwegian study in 1985/1986 where individual samples from the same areas were analyzed. Teh total TEQs, including dioxin-like PCBs, ranged from 31 to 42 pg TEQs/g fat in Norway and from 45 to 49 pg TEQs/g fat in Lithuania. The mean concentration of PCDDs/PCDFs in teh Norwegian samples (10.4 pg TEQs/g fat) was slightly lower than in the Lithuanian samples (14.8 pg TEQs/g fat). Dioxin-like PCBs were found to contribute two to three times more to the total TEQs than the PCDDs and PCDFs. Major contributors among the dioxin-like PCBs were PCBs 126, 156, 114, 118, and 170. Comparison of the present data with those obtained in the Norwegian study in 1985/1986 shows that for PCDDs/PCDFs the mean TEQ levels have decreased by about 37% in the 7-yr time span, while the levels of total PCBs, as determined by packed-column gas chromatography, have remained unchanged or only slightly decreased. Future studies are necessary to confirm this potential temporal trend.
Milk samples of 14 women were analyzed for PCBs (polychlorinated biphenyls), p,p'-DDE, and HCB (hexachlorobenzene) during 11 intervals of a 120 day-lactation period. A general downward trend in residue levels was evident, and a statistically significant decline was observed for residue levels of PCBs (P less than 0.01) and HCB (P = 0.02) on the milk fat basis. Primipara (n = 9) had from 1.5 to 2.1 times higher mean residue levels than mothers nursing their second or third child (n = 9). Significant declines in residue levels during lactation of the first child were found, while no pronounced changes in residue levels were observed during lactation of the second or third child. Overall, residue levels in this study were lower than corresponding levels found earlier in Norway, and within the range of the corresponding levels found in another Norwegian human milk survey done at the same time.