A computer modelling technique developed by Australian scientists to minimise the impact of agricultural pesticides on rivers, lakes and groundwater is attracting world attention.

Researchers at CSIRO developed the Pesticide Impact Rating Index (PIRI) model to help farmers, resource managers and regulators minimize the chances of a chemical pesticide ending up in the local water supply.

The result is a benefit for the environment, as well as a new way to back Australia's claim to export some of the cleanest, greenest agricultural produce in the world.

The PIRI technique has already aroused the interest of United Nations International Atomic Energy Agency and several Asian countries, who hope to employ it in areas where pesticide contamination of surface and groundwater is a serious concern.

PIRI calculates an individual pesticide's impact on surrounding water bodies by taking into account its chemical properties, application and frequency, and then factoring in seasonal and soil variables.

"This allows us to predict with 80% certainty whether or not traces of any pesticide used will end up in surrounding water supplies," says CSIRO Land and Water scientist Dr Rai Kookana.

"PIRI's ability to forecast the likelihood of pesticide water contamination means farmers, resource managers and regulatory bodies can make more informed decisions about how they use pesticides," he says.

"As a result land users may reduce chemicals, modify their spray pattern and land usage or introduce a buffer zone between where pesticides are used and nearby rivers or creeks."

Pesticides worth more than $1000 million dollars are applied in Australia each year and can reach surface waters and groundwaters through run-off, soil erosion and leaching.

Dr Kookana says the solubility and chemical properties of the pesticide also determine how likely it is to move into the water bodies.

The PIRI program which can deal with hundreds of chemicals was designed and written by CSIRO Mathematical and Information Sciences statisticians Dr Ray Correll and Mrs Ros Miller.

The program has attracted high international interest because it contains a wide range of complex environmental and pesticide chemical information. Its development was supported by the Land and Water Resources Research and Development Corporation (LWRRDC).

Drs Kookana and Correll are now working with several agencies in Australia, the Geneva-based UN International Atomic Energy Agency and Malaysia and Thailand, all of whom want to use PIRI in areas where pesticide water contamination is of serious concern.

Further development, again supported by LWRRDC, is under way and the PIRI computer program is expected to be made available around Australia in 2001.

More information:
Dr Rai Kookana, CSIRO Land and Water (08) 8303 8400
Dr Ray Correll, CSIRO Mathematical and Information Sciences (08) 83038769
Mrs Rosalind Miller CSIRO Mathematical and Information Sciences (08) 8303 8768
Ms Margaret Bryant, CSIRO Land and Water (08) 9333 6215 or mobile 0417 247 241