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Abstract
Concentrations of 2,3,7,8–substituted polychlorinated dibenzo‐p‐dioxins (PCDDs) and di‐benzofurans (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. The 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 the 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.