The Pesticide Impact Rating Index (PIRI)

After ten years of research, the off-site impacts of different pesticides and land uses can be compared using a simple risk indicator. The Pesticide Impact Rating Index (PIRI) is a free software package developed by CSIRO with support from Land & Water Australia and other agencies, both here and overseas.

• Download the PIRI Fact Sheet (PDF, 276 kB)
• Download the PIRI brochure (PDF, 602 kB)
• Download the software

The cumulative effect of pesticides and other contaminants on biodiversity and human health is an important environmental issue.

In Australia alone, more than $1 billion worth of herbicides, fungicides and insecticides are applied each year. The problem is that pesticides are mobile, so not all the pesticide sprayed on a field remains on site. Varying amounts of these substances can reach surface and ground waters through spray drifts, run-off, soil erosion and leaching, with unintended impacts on non-target organisms.

The offsite effects of pesticides are of increasing concern to planners, catchment managers, consumers, regulators and industry. Assessment of the risks is difficult, especially when dealing with complicated physical, chemical and biological interactions at the catchment scale.

Searching for a practical solution

Dr Rai Kookana first suggested the conceptual basis for a new approach to pesticide risk assessment at a national workshop in 1988. He saw an opportunity to devise and implement a practical solution to aid risk assessment, based on a solid scientific understanding of the factors that determine how likely a pesticide is to move into nearby waterways.

Some time later, in 1996, a CSIRO team comprising research scientist Dr Kookana and statisticians Dr Ray Correll and Ros Miller (CSIRO Mathematical and Information Sciences) set out to find a way of calculating a pesticide's likely effect on water quality, taking into account its toxicity, chemical properties, application rate and frequency, and factoring in local site conditions along with seasonal and soil variables.

With the support of Land and Water Australia they created the Pesticide Impact Rating Index (PIRI), a tool designed to assist pesticide users and regulators to make informed decisions about the best product to use given their own individual circumstances, taking into account the likely impact of pesticides in the local environment.

Dr Kookana describes PIRI as a simple risk indicator for different pesticides and cropping systems. It is based on clever integration of the various factors that determine the impact of pesticides in the environment:

• the value of the asset (e.g. an adjacent water resource that may be threatened)
• the sources of threat (e.g. a certain pesticide load) to the asset
• the transport pathways (e.g. spray drift) by which the threat is released.

Information about pesticide properties, soil and environmental conditions, and site specific factors is built into the process.

Widespread appeal

Through a series of demonstrations and case studies, PIRI is generating widespread national and international interest among the scientific community, and within industry and government.

PIRI has been utilised by regulators and natural resource managers in Western Australia , Tasmania and Victoria . The United Nations Food and Agriculture Organization/International Atomic Energy Agency will be using PIRI in a Food and Environment program project involving 12 countries across Asia, South America and Africa .

An independent evaluation of the benefits of PIRI, commissioned by Land and Water Australia , calculated the net benefit as $13.6 million, with a return on investment of 37 to 1. The benefits include:

• savings in pesticides usage and monitoring costs
• greater awareness and understanding of pesticide toxicity
• better choice of pesticides for particular sites and better choice of land management practices
• environmental benefits (reduced impacts on aquatic health and biodiversity)
• social benefits - lowered anxiety of water managers and consumers regarding the effectiveness of monitoring of pesticides.

CSIRO continues to support the adoption of PIRI in catchments around the world.

Every time PIRI is applied to a new catchment, the CSIRO research team has an opportunity to gather new data on the behaviour of pesticides in soils and waterways, leading to further scientific discoveries.

For more information about PIRI

Contact Dr Rai Kookana, CSIRO Land and Water