Trends in ambient levels of DDT and HCH residues in humans and the environment of Delhi, India.

Monitoring of DDT and HCH residues in abiotic and biotic components of the environment of Delhi during 1988 to 1989 revealed low to moderate levels of these insecticides in soil, earthworms, birds, buffalo milk, water, freshwater clams, fish, human fat, human blood and breast milk samples. Total HCH residues were less than those of DDT in all the samples. This survey indicates (in spite of the continued use of DDT and HCH in the country) a general decline in the levels of DDT residues in most of the samples studied when compared to previous surveys. Although the levels of DDT and HCH residues in fish and river water were below the permissible limits, those in human samples remained fairly high.