Absorption of DDT and HCH residues by wheat during storage in rural houses treated with these insecticides for malaria control

Abstract

Wheat kept in gunny bags of 20 kg capacity in rural houses sprayed with DDT or HCH for mosquito control was found to acquire the residues of these insecticides up to 4.40 or 22.14 mg kg −1, respectively, during an 8 month storage period. Wheat stored in sealed polyethylene bags of 20 kg capacity also absorbed residues of these insecticides up to 3.17 and 14.12 mg kg −1, respectively. Samples kept in gunny or polyethylene packets of 100 g capacity absorbed DDT and HCH residues at levels higher than those kept in bags of 20 kg size. This may be due to their relatively large surface area available for exposure to the ambient environment. Absorption of residues of DDT and HCH by wheat stored in sealed polyethylene bags suggests that considerable transference of these insecticide residues can occur through vapour phase. Thus, the potential exists for the contamination of food commodities with substantial amounts of residues during their storage in rural premises treated with insecticides for malaria control and this may have significant implications in the regulation of insecticide residues in foods.