Risk assessment and management of elected pesticides generally used in Bangladesh

Abstract

Exposure to pesticide imposes serious long term risk to human beings. The exposure level ("0.018 mg/kg/day) of pesticides in Bangladesh is much higher than that of expected level ( 0.005 mg/kg/day). So, there is a significant risk of exposure hazards of pesticides to human and other nontarget species in Bangladesh. Runoff, spillage, washing of pesticides' containers in pond water contribute pesticides residues to ground water and surface water in Bangladesh. 44.8 microgram /liter concentration of DDT entered into pond from adjucent rice field through drains and soil. Concentration of 19.5 ppb, 35ppb, 10ppb of DDT in water samples of Bangladesh Institute "of Technology, Khulna; Kitonkhola, Barishal and Amin Bazar, Mirpur respectively and 0.23 ppb, 0.198 ppb of heptachlor in water samples of Amin Bazar, Mirpur and Kitonkhola, Barishal of Bangladesh exceed acceptable limits of pub in case of DDT and 0.03 ppb in case of heptachlor. So, there is a significant risk of water pollution. Ground water and surface water vulnerability in the case of DDT and Atrazine were carried out. Application of 1-1.12 kg/ha rate for Atrizine in low land rice field of coastal area impose moderate risk on ground water. Pesticide contamination of surface water by runoff and spillage, adulteration of pesticides in pond drainage from irrigation project cause toxicity to fish species and aquatic organisms. Considerable amount of organochlorine insecticides were found in water samples of depressions near rice fields which indicate lacks of control mechanisms. Considering storage loss, Tuyen's equation has been modified to estimate pesticide residue in human body. However this requires further experimental varification. Presence of significent amount of pesticide residue in food, dry fish etc are matter of concern. The residue of pesticide in human body due to consumption of rice and wheat was estimated to be 1.76 x 10-5 mg/day/person in Bangladesh. Although the level of pesticide residue in daily consumption of food is still low as compared to other developing countries, yet it is a matter of concern due to lack of medicre facilities and poverty in Bangladesh. Isotherms of carbicorn, malathion, diazinon in alluvial soil were established. Atraction of carbicorn, malathion to this soil is greater than that of diazinon. Thus use of diazinon impose greater risk than use of carbicorn and malathion.