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. Pesticide use has increased substantially in Australia and globally over the last two decades, partly due to changes in tillage practices. Some 400 chemically active ingredients, of varying properties, are currently available in Australia alone. Pesticide residues have been found, mostly at acceptable levels, in food commodities and in surface and ground water bodies in Australia. Such contamination needs to be minimized. However, the variety of pesticides, their use under a range of soil and climatic conditions and the complexity 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 for risk assessment in tropical regions. The effect of farming practices, e.g. conservation tillage, on run-off and leaching losses, needs better understanding and quantification. Such studies aimed at providing knowledge on the fate and persistence of pesticides must be supported by sound information on pesticide usage (inputs), particularly at catchment-scale. Correct sampling and analytical protocols are crucial for any research or monitoring study. 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.