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Assessments of human exposure to persistent organochlorine insecticides (OCI) through biological monitoring offers a profound criteria to evaluate the magnitude of potential health risk, if any, due to use of these chemicals. Residues of these chemicals especially DDT and HCH have been identified and reviewed in man and his environment from different parts of the world however, by comparison very high levels of DDT and its metabolites have been reported in human body fat, blood and milk samples in India. Since there is a definite relationship between the amount of DDT and its residues in blood and those present in human fat depot, blood can be easily be used for assessing the total body burden of persistent OCI in various populations. In view of fragmentary reports on the levels of DDT and HCH in human blood samples from India which categorically pertain to the general population of urban areas like Delhi and Lucknow. The authors attempted to provide a database on residues of DDT and HCH including other cyclodiene compounds, e.g. heptachlor, heptachlor epoxide, aldrin, oxygchlordane, HCB and dieldrin in blood samples collected from general population of Ahmedabad (rural) area.

Concentrations of dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH) were determined in 313 human omental fat samples collected from subjects from all five zones of India during 1977-1980. The median concentration of 2,2-bis-(p-chlorophenyl)-1,1-dichloroethylene (p,p'-DDE), total DDT, beta HCH, and total HCH were 3.4, 6.0, 1.3, and 1.9 mg/kg, respectively. The calculated national mean levels for DDT and HCH were 11.1 and 3.5 mg/kg, respectively. Although the values of DDT and HCH were not as high as those reported earlier, there is still a need for close monitoring of the bioaccumulation of these chemical residues in the Indian population.

Urine samples of workers in a small-scale unit manufacturing Direct Black 38 were analyzed by high-pressure liquid chromatography for the presence of benzidine and mono and diacetyl benzidine. Acetylated metabolites were found in all the urine samples, and benzidine was found in all except two. Two workers excreted very high levels of benzidine and its metabolites in their urine. This study highlights the potential risk of bladder cancer in such units of developing countries where manufacture of benzidine-based dyes is yet to be regulated.