Levels of polychlorinated biphenyls (PCBs) and organochlorine pesticides in human milk and blood collected in Osaka Prefecture from 1972 to 1977

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Annual surveys of levels of polychlorinated biphenyls (PCBs) and organochlorine pesticides in human milk and blood obtained from residents in Osaka Prefecture were made for six years from 1972 to 1977. The levels of PCB in human milk were within the range reported by others, and the average concentrations were in the range from 0.03 to 0.04 ppm on the whole basis of milk, and were approximately 10 times higher than those found in blood. There were 15 exceptional milk samples whose PCB level on whole basis exceeded 0.1 ppm. The PCB levels in human milk increased from 1972 to 1974, and decreased from 1974 to 1976. However, these changes are not statistically significant, because there has been continuous environmental contamination with PCB for many years so for. There was a proportional relation between the PCB levels in blood and in milk obtained from the same mothers. The PCB levels in milk and blood of mothers who had given first childbirth were higher than those of mothers who had given the second or more childbirth. A gradual decrease in β-BHC level was observed during this period. The levels of p,p′-DDE, p,p′-DDT and dieldrin were fairly constant from 1972 to 1976. However, remarkable decrease in the levels of the organochlorine pesticides was found in 1977.

Most of the residual PCB components and their chlorobiphenyl contents in the human milk were clarified. It was proven that there were remarkable amounts of tri- and tetrachlorobiphenyls. A specific structure of the residual components was 4,4-substitution pattern.

All mothers and babies did not show any apparent clinical symptoms which were related to the toxic effect of the PCBs over the period of time. However, further studies concerning the toxic effect of PCBs to human infants and understanding of long-term trends of chlorinated hydrocarbon levels in human milk are necessary.