Levels of organochlorine pesticides and polychlorinated biphenyls (PCBs) in mothers' milk collected in Osaka Prefecture from 1969 to 1976.

Long-term investigations of polychlorinated hydrocarbon levels in mothers' milk were made from 1969 to 1976. The levels of p,p'-DDE, p,p'-DDT, dieldrin and PCB in mothers' milk were within the range reported by others. However, beta-BHC(Hexachlorocyclohexane) levels in the milk were 10 times that found in non-Japanese. A gradual decrease in the beta-BHC level in the milk was observed during this period. In contrast, the levels of p,p'-DDE, p,p'-DDT, dieldrin and PCB were consistent for the 7-year period. A significant correlation between the levels of PCB and p,p'-DDE in mothers' milk and blood was observed in the 1974-1976 samples. However, after prohibition of the use of chlorinated hydrocarbons, this relationship was less apparent in the 1972-1973 samples.