Atrazine review history and regulatory outcomes

Nomination for review

In December 1995 the APVMA (formerly the NRA) began a review of atrazine as part of the Existing Chemical Review Program which was established to systematically review a number of Agvet chemicals which had been on the Australian market for some time. Atrazine was nominated for review because of concerns over possible links to cancer, its potential to contaminate ground and surface water, lack of Maximum Residue Limits (MRLs) for major commodities, and a reported lack of efficacy for some uses.

Interim Review Report

In November 1997 the APVMA released the Atrazine Interim Review Report. The interim report found that there were no major toxicological concerns with atrazine active constituent and moreover, that the use of atrazine products posed no undue hazard to most users. As well, new conditions for use of atrazine were implemented in order to reduce chemical handling by workers, and to reduce drift and runoff into water bodies. Some of the key changes included:

Cancellation of industrial and non-agricultural uses of atrazine (including home-garden uses). Cancellation of sale and supply of these atrazine products, took effect from 31 December 1998. The application of existing stocks was allowed to continue until 30 June 1999.
Inclusion of more extensive safety instructions on product labels to reduce chemical handling by workers, and to reduce spray drift and runoff into water bodies.
Deletion of MRLs for commodities for which there were no current use patterns (citrus, grapes and pineapples).

The APVMA found that additional environmental and residue information were required and registrants were given up to three years to generate this data. Assessment of these data led to the development and publication of a draft final report.

At the same time as the interim review was released, restrictions on the use of atrazine were introduced in response to detections of atrazine in water bodies, and to minimise any further potential risks to the environment. These were:

no mixing/loading or application within 20 m of any well, sink holes, intermittent or perennial stream
no application within 60 m of natural or impounded lakes or dams
no use in channels and drains
a maximum annual rate of application of 3 kg active ingredient (ai)/ha in all crops except plantation forestry. In plantation forestry, the maximum rates were limited to 4.5 kg ai/ha per year in sandy soils and those defined as ‘highly erodible’, and 8 kg ai/ha per year in clay loams and heavier textured soils.

These restrictions remain in force.

Draft Final Review Report

In April 2002 the APVMA released the Atrazine Draft Final Review Report for public comment. At the time of the release of the draft final report, a number of new overseas studies were published which raised additional concerns that atrazine might cause adverse developmental and reproductive problems in frogs. Because of these new concerns, the APVMA delayed finalisation of the review in order to investigate these new claims and reassess the toxicological and environmental risks of using atrazine.

Second Draft Final Review Report

In December 2004 the APVMA released the Atrazine Second Draft Final Review Report. This report considered all regulatory action taken since the release of the 1997 interim report recommendations, new residues and environmental data, and assessment of the US EPA frog studies.

The APVMA found that atrazine was unlikely to have an adverse impact on amphibians at existing levels of exposure. However, it concluded that the issue of atrazine and amphibians should be revisited if additional data demonstrated that atrazine posed a hazard to frog populations at realistic levels of exposure.

The APVMA also found that atrazine does not pose a risk to human health, but the use of products containing atrazine in non-agricultural situations might pose a risk to the environment. Changing the use instructions on product labels would reduce or eliminate these risks.

The APVMA was satisfied that varying product labels and approvals would ensure that atrazine products would continue to meet the requirements for continued registration and use in Australia.

In the 2004 report the APVMA proposed:

amending product labels to include:
- a larger buffer zone and additional precautionary statements
- a new withholding period of 28 days for grazing on all crops except canola
- details for reporting incidents of herbicide resistance or breakdowns in efficacy.

For more information please contact the Chemical Review Program on (02) 6210 4749 or by email to chemrev@apvma.gov.au