Chemicals in the News: Atrazine
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Last updated 5 April 2011
Atrazine is a triazine herbicide currently registered in Australia for the control of grass and broadleaf weeds in crops such as sorghum, maize, sugarcane, lupins, pine and eucalypt plantations, and triazine tolerant (TT) canola.
A great deal of research has been undertaken investigating potential human health and ecological impacts of atrazine. The generally consistent findings flowing from this body of research have provided regulatory authorities around the world with some significant confidence that the chemical can be used safely, subject to a range of conditions.
Good quality, new scientific studies are evaluated against this data bank of existing research by scientific and regulatory agencies as they become available. Recent research suggesting adverse impacts on human health and on amphibians, for example, has gone through this process. To date, no international regulator has made adverse human health or environmental findings against atrazine that are not consistent with Australia's current standards and controls.
The APVMA concluded an extensive review of atrazine in 2008 and continues to be satisfied that it can be safely used in Australia, subject to those conditions outlined on product labels.
Tighter regulations for the use of atrazine have been introduced by the APVMA since 1997, including the cancellation of industrial and non-agricultural uses and a range of label instructions designed to reduce the risk of atrazine entering waterways. For more information, see the full details of the atrazine review.
In Australia, the APVMA and its advising agencies (the Office of Chemical Safety and Environmental Health in the Department of Health and Ageing; and the Department of Sustainability, Environment, Water, Population and Communities) regularly consider new atrazine studies as they become available. In 2010, for example, the APVMA commissioned OCSEH to assess data published at that time suggesting that atrazine might be responsible for adverse reproductive and developmental effects in humans through an endocrine mode-of-action (MOA). The report, published in June 2010, found that these concerns did not lead to any amendment to the existing human health risk assessment.
See the full report - Atrazine Toxicity: Analysis of Potential Modes of Action (PDF, 633kb).
Two additional studies of particular note that were reviewed in 2010 were one suggesting that atrazine might be associated with the birth defect (gastroschisis) and another linking atrazine to feminization of frogs. The advice the APVMA received was that neither provided evidence that would warrant a reconsideration of the APVMA’s regulatory settings.
See the full copies of these reports:
- Agricultural-related chemical exposures, season of conception, and risk of gastroschisis in Washington State (external site)
- Hermaphroditic, demasculinized frogs after exposure to the herbicide atrazine at low ecologically relevant doses
Atrazine is widely used throughout the world.
United States of America
The United States Environment Protection Authority (U.S. EPA) reviewed atrazine in 2003 and re-affirmed its registrations.
In June 2003 the United States Environment Protection Authority (U.S. EPA) requested further studies to assess whether atrazine affected amphibian gonadal (sexual) development. The EPA received and assessed the requested studies and other available research and in 2007, concluded that atrazine does not adversely affect amphibian sexual development. For more information, see EPA Atrazine Updates (external site).
In October 2009, the EPA announced a further review of atrazine (external site) to reconsider existing data and evaluate new studies published since their last review, focusing mainly on risks to human health. For more detailed information see Atrazine Science Reevaluation: Potential Health Impacts (external site).
The Canadian regulatory authority, the Pest Management Regulatory Agency (PMRA) concluded in 2004 that the use of atrazine did not entail an unacceptable risk to human health, provided that the required mitigation measures were implemented.
The European Commission (EC) excluded atrazine from a re-registration process in 2003 because the registrants did not supply sufficient water monitoring data.
Specifically, the commission found that the data was ‘insufficient to demonstrate that in large areas concentrations of the active substance and its breakdown products will not exceed 0.1 μg/l in groundwater. Moreover it cannot be assured that continued use in other areas will permit a satisfactory recovery of groundwater quality where concentrations already exceed 0.1 μg/l in groundwater.’ See the European Commission decision document (external site).
It is frequently asserted that atrazine has been banned in the EU. This is an incorrect interpretation of the EC decision. Atrazine has not been assessed and de-registered because of a human health or environmental concern. It is not on any EU ‘banned list’ and could theoretically be reregistered in the EU should the product registrant provide all the required data. Terbuthylazine, a herbicide very closely related to atrazine, is still in use in the EU and is under assessment (external site).
International Agency for Research into Cancer
The IARC published a detailed evaluation of atrazine in 1999 (external site) in which they concluded that earlier onset of tumours in one strain of female rats dosed with atrazine was unique to that strain and not relevant to humans. Thus it downgraded its earlier classification of atrazine from Group 2B ‘possible human carcinogen’ to Group 3 ‘not classifiable’.
WHO/FAO Joint Meeting on Pesticide Residues (JMPR)
The Joint Meeting on Pesticide Residues (JMPR), a joint committee of the World Health Organization (WHO) and the Food and Agriculture Organization (FAO), re‑assessed atrazine in September 2007 and published the final report in October 2009. The JMPR established a higher Acceptable Daily Intake (ADI) than the Australian standard. In October 2010 the WHO recommended a new drinking water standard for atrazine of 100 parts per billion, an increase from the previous WHO standard of two parts per billion.