Atrazine, which is used primarily in broadacre agriculture on triazine tolerant (TT) canola, sorghum and maize, came under review by the APVMA, who were investigating the chemical after concerns were raised over human and animal carcinogenicity, environmental impacts including the potential for atrazine to contaminate ground and surface water, and residue and efficacy uncertainties.

"Farmers are pleased they can continue to use the product without increased cost or regulation," said the chairman of the Victorian Farmers Federation agricultural and veterinary chemicals committee, Geoff Kendell.

"Atrazine plays a very important role for many farmers, especially those growing TT canola.

"Not only does it play its part in reducing the risk of ryegrass resistance to other key chemicals such as glyphosate, it can also be used to control brome grass, which is an issue that is a major concern to many farmers across Australia."

The APVMA review recommended only minor changes to the use of the product, including further research into the use of atrazine on raised beds, due to concerns about the chemical running off the beds and contaminating waterways.

"The APVMA has acted on new information suggesting a potential risk of atrazine entering waterways through the use of the chemical post-emergence on triazine tolerant canola in raised bed cropping systems," said the APVMA manager of public affairs, Simon Cubitt.

"The APVMA is requiring registrants to collect data to enable it to further evaluate this issue."

Concerns about carcinogenicity were found to be unwarranted in the APVMA's research and regulatory actions in 1997 addressed the remaining issues including maximum residue limits (MRLs), the efficacy issue and contamination of waterways.

The key debate since then has focused on concerns that low concentrations of atrazine may cause developmental effects in frogs.

This issue has been the subject of significant scientific investigation both in Australia and the United States.

In both jurisdictions authorities have concluded that the weight of evidence does not support the claimed effects.