Long-term occupational exposure to DDT.

Blood serum of twenty workers occupationally exposed to DDT for an average duration of 14 years was analysed for organochlorine pesticides by gas-liquid chromatography with an electron capture detector. Significant levels of BHC, p,p'-DDT, p,p'-DDD and p,p'-DDE were detected. A higher incidence of total DDT equivalent, about 10 times, was observed in DDT exposed workers when compared with a comparable sample of unexposed persons from the general population. Levels of DDT in serum of occupationally exposed workers were more than the permitted level of 200 ppb. The daily intake was computed to be about 10 mg/man/day as against 0.25 mg--the acceptable daily intake. Abnormal nerve conduction was encountered in a few cases of DDT sprayers. No significant correlation was observed between the total DDT equivalent in serum and duration of occupational exposure in workers. Levels of BHC in controls was 2.3 times the level in exposed workers, possibly due to induction of hepatic drug metabolising enzymes by high levels of DDT in the latter group. Findings are discussed in the light of existing knowledge of the bio-chemical effects evoked due to residual intoxication of DDT during occupational exposure.