The distributions of organochlorine pesticide residues in raw milk and in commercial milk for the seasons in each district (eight prefectures) (January, 1970 to March, 1971) were investigated.
Generally, in the west area of Japan where the organochlorine pesticides were much used in quantity in the fields, the pesticide residue levels in milk were higher, on the other hand, the levels in Hokkaido and Miyagi prefectures were relatively lower. The residues of β- and total BHC in milk were much higher in the west area of Japan. Little difference was observed in the residues of other pesticides (r-BHC, pp'-DDT, pp'-DDE, pp'-DDD, total DDT and dieldrin) in milk. In the present in vestigation aldrin and endrin were not detected in milk. It was found that the contamination of milk by the organochlorine pesticides showed a decrease by about 50% in total BHC residues at the end of this experiment, compared with at the beginning. In order to elucidate from what source the contamination of milk by the organochlorine pesticides, especially β-BHC, was derived, the organochlorine pesticide residues in various kinds of cow feeds were examined. Because BHC was abundantly detected in rice straws, it has been concluded that a large portion of BHC in milk was derived from rice straws used as cow feeds.
At the same time, the variation of organochlorine pesticide residues in commercial milk were examined by location and by season, and also it was found that the organochlorine pesticides were detected in commercial milk.
