Persistence of ethion residues on cucumber, Cucumis sativus (Linn.) using gas chromatography with nitrogen phosphorus detector.

Residues of ethion were estimated in cucumber by gas liquid chromatography following three applications of the insecticide at 375 and 750 g a.i ha(-1). The average initial deposits of ethion on cucumber fruits were found to be 2.40 and 4.97 mg kg(-1) at single and double dosages, respectively. Residues of ethion dissipated below the maximum residue limit (MRL) of 0.5 mg kg(-1) in 7 days. Half-life (T1/2) for degradation of ethion on cucumber was observed to be 2.92 days at recommended dosage. A waiting period of 7 days is suggested for safe consumption of cucumber.

Risk assessment through dietary intake of total diet contaminated with pesticide residues in Punjab, India, 1999-2002.

Forty-six samples each of vegetarian and nonvegetarian total diet consumed from March 1999 to December 2002 by male subjects in the age group of 19-24 years were analyzed to assess their risk through dietary intake with respect to pesticide residues. The results revealed low dietary intake of levels of Sigma-dichlorodiphenyltrichloroethane (DDT) and which were almost comparable to levels reported in developed countries. The results are indicative of contamination of total diet with pesticide residues despite a ban on the use of DDT and restricted use of lindane in agriculture only. Predominance of lindane residues indicates that liquid milk was a main contributory source as it comprises almost 21% to the total diet consumed per day. Concerted efforts by regulatory authorities and emphasis on judicious use of agrochemicals in pest control are required to decrease the burden of these chemicals in food stuffs to levels safe for dietary intake.

Contamination of bovine (buffalo, Bubalus bubalis (L.)) milk from indoor use of DDT and HCH in malaria control programmes.

Samples of bovine (Buffalo, Bubalus bubalis (L.)) milk collected from randomly selected houses of Ludhiana and Sangrur districts of Punjab, India, where DDT and HCH, respectively, had been sprayed for the control of malaria, were analysed for insecticide residues between September 1985 and June 1986. The average concentration of DDT residues in samples from the DDT sprayed area were approximately 4-12 times higher than those in the corresponding samples from HCH sprayed areas. Mean levels of HCH residues in samples from the HCH sprayed area were greater than those in samples from DDT sprayed areas by factors of 2-11. Milk samples collected from four rural houses in each district before and after applications of DDT or HCH for mosquito control also showed that indoor use of these insecticides results in a substantial increase in residue levels. About 74% of the samples analysed contained DDT residues above the extraneous residue limit of 0.05 mgkg-1 (whole milk basis). Estimated maximum daily intakes of DDT and beta-HCH through consumption of contaminated milk by 1-3-year-old children exceeded their acceptable daily intakes by nearly three and five times, respectively.

Contamination of stored food and feed commodities from indoor use of HCH and DDT in malaria control programmes.

Samples of wheat grain, straw, flour and green fodder taken from houses sprayed with either HCH or DDT for mosquito control showed the presence of HCH residues at concentrations of up to 91.2, 208.8, 33.1 and 459.0 mg kg-1 and DDT residues up to 11.3, 86.1, 2.2 and 5.4 mg kg-1, respectively. The mean level of HCH residues in samples of wheat grain collected from randomly selected houses in areas sprayed with HCH for the control of malaria was approximately 8 times higher than that for corresponding samples from DDT sprayed areas. In contrast, DDT residues in wheat grain samples from the DDT sprayed area were 3 times higher than the samples from the HCH sprayed area. The results suggest that significant amounts of residues of HCH and DDT become transferred to commodities stored in houses sprayed with these insecticides for mosquito control.