Minimizing the off-site impact of pesticides from agricultural system - a risk based approach
2009
Varca, L.M. | Fabro, L.E. | Bajet, C.M. | Peralta, G.A., Philippines Univ. Los Baños, College, Laguna (Philippines). National Crop Protection Center
Off-site assessment of impact of pesticides used in agriculture done in selected tributaries of Laguna Lake and Taal Lake [Philippines] indicated that certain pesticides used by farmers in the vicinity of these tributaries were present in water and sediment of these rivers. Some pesticides detected were deltamethrin, cypermethrin, L-cyhalothrin, triazophos, metamidophos, diuron and butachlor. This provided a snapshot assessment to establish whether pesticides were moving off-site or not. The Pesticides Impact Rating Index (PIRI), a computer software developed by scientists from CSIRO [Commonwealth Scientific and Industrial Research Organization], Australia was applied for the assessment of impact of pesticides on surrounding water bodies. The tool was able to classify pesticides of concern due to risk of off-site migration or risk of adverse ecotoxilogical impact from each land use investigated. The PIRI was customized for Philippine conditions. It was populated with local pesticides use data and associated environmental fate and toxicity properties. A version rate of the PIRI was developed in the local language (Filipino) to encourage the wider use of the screening tool by regulators and resource managers. Pesticide residue monitoring validated the mobility impact of the pesticides assessed by the PIRI with some exception: the detection of pyrethroids was not consistent with the PIRI assessment. Ecotoxilogical studies indicated that some pesticides detected in waterways were below the levels at which it can result to acute toxicity to tilapia, local shrimp (Macrobrachium lar), and duckweed (Lemna sp.). Studies on early life stages of Tilapia indicated that certain pesticides can have chronic toxic effects. Abnormalities in fish size, yolk sac distribution, deformities were observed. Environmental fate studies on various Philippine soils indicated a narrow range of half-life. Pesticides have shorter persistence under tropical conditions as compared to those reported from temperate countries. A range of strategies has been suggested to minimize off-site transport of pesticides. Simple measures such as plugging the leaking bunds in rice paddies have been suggested to minimize direct source of pesticides migration into adjacent streams. Other strategies have been suggested. Various stakeholders have been involved since the initiation of the project. Annual workshops were held with the stakeholders to provide regular update on the project and facilitate two-way flow of information. Training-workshop on the use of PIRI was conducted involving researchers from regulatory and monitoring agencies of the government such as LLDA [Laguna Lake Development Authority], BSWM [Bureau of Soils and Water Management] FPA [Fertilizer and Pesticide Authority], EMB-DENR [Environmental Management Bureau-Department of Environment and Natural Resources] and PCARRD [Philippine Council for Agriculture, Forestry and Natural Resources Research and Development].
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