Pesticide fate in farming systems: Research and monitoring

Pesticides, being toxic by design, cause considerable public concern about their possible nontarget impact on the ecosystem and human health. Pesticid e use has increased substantially in Australia and globally over the last t wo decades, partly due to changes in tillage practices. Some 400 chemically active ingredients, of varying properties, are currently available in Aust ralia alone. Pesticide residues have been found, mostly at acceptable level s, in food commodities and in surface and ground water bodies in Australia. Such contamination needs to be minimized. However, the variety of pesticid es, their use under a range of soil and climatic conditions and the complex ity of processes governing their fate make this task particularly daunting. Furthermore, as little local data is available for Australian conditions, there is danger in extrapolating overseas Temperate Zone data, especially f or risk assessment in tropical regions. The effect of farming practices, e. g. conservation tillage, on run-off and leaching losses, needs better under standing and quantification. Such studies aimed at providing knowledge on t he fate and persistence of pesticides must be supported by sound informatio n on pesticide usage (inputs), particularly at catchment-scale. Correct sam pling and analytical protocols are crucial for any research or monitoring s tudy. Analysts are faced with a continuous demand for newer, cost effective and improved analytical methods for pesticides and their metabolites, for better sensitivity and quality control.