STUDIES ON DDT AND ITS METABOLITES IN ENVIRONMENT, HUMAN TISSUES AND THEIR HEALTH EFFECTS

Abstract

DDT residue in soil from 50 sites surrounding a DDT factory in Delhi were monitored. DDT was detected in all the samples. Total DDT ranged from 0.498 to 7.270 ppm with a mean value of 1.670 ppm. The highest concentration of total DDT, 7.270 ppm, was detected in the soil from Durga Nagar in the vicinity of a DDT factory. Other areas surrounding DDT factory contained moderate to high levels of DDT and its metabolites in soil. West Zone soils were heavily contaminated with DDT residues as compared to other zones of Delhi. Blood samples from 50 occupationally unexposed volunteers of Delhi area were examined for DDT residuesl The total DDT concentration in the whole blood ranged from 0.112 to 0.663 ppm in males and 0.053 to 0.560 ppm in females. The DDT metabolites detected were : p,p*-DDE, o,p'-DDT, p,p'-DDT and very low quantities of p,p'-DDD. DDE accounted for most of the total DDT. Age was shown to have no effect on blood DDT levels but dietary habits influenced the accumulation of DDT in the blood; non-vegetarians had higher total DDT in the blood as compared to vegetarians (p<0.05). Transfer of organochlorine pesticides from mother to fetus was studied in 50 women. The concentrations of DDT and its metabolites were examined in maternal blood, placental tissue and umbilical cord blood of the same mother/child pair. Residue levels of DDT and its metabolites were detected in all the samples analyzed indicating their transfer from mother to fetus via placenta. No effect of age and dietetic habits was found on accumulation of DDT and its metabolites in pregnant women. The excretion of DDT and its metabolites in human milk was studied. The circulating blood and breast milk of nursing Indian mothers were examined for the presence of DDT and its metabolites. The mean total DDT in milk (2.030 ppm) was significantly higher than that of blood (0.253 ppm; p<0.001). The daily intake of total DDT residues by an Indian child weighing 5 kgs and consuming 1 kg of milk per day was calculated to be 0.406 mg/kg body weight per day- Premature labour and toxemia of pregnancy due to the higher concentrations of DDT and its metabolites were studied. Considerably higher amounts of DDT residues were reported in the maternal blood, placental tissue and umbilical cord blood of women undergoing premature labour and toxemia of pregnancy as compared with women with full term pregnancy. The following trend was observed: Premature > Toxemia > Full term Storage of DDT residues in relation to disease was investgated. High DDT levels were reported in the blood and uterine tissues of women undergoing hysterectomy as compared to blood and uterine tissues collected at the time of autopsy. The total DDT concentrations in blood and uterine tissues showed no correlation with the age. The health effects posed by DDT residues in general population were studied to explore the possible health hazards. No consistent pattern of abnormalities was present either in medical histories or physical examination, nor were any clinical symptoms found to be associated with the concentration of DDT in the blood. There was also a paucity of abnormal results in the biochemical studies. No correlation was observed between DDT concentration in the blood and altered biochemical test results, if any. The Erythrocyte Sedimentation Rate (ESR) and hemoglobin levels were within the normal limit.