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Additional Scientific Reviews of Herbicide Atrazine Completed

Release Date: 10/31/2003
Contact Information:

David Deegan 617-918-1017 /

(10/31/2003) In January 2003, EPA issued an “Interim Re-registration Eligibility Decision” (IRED) for the widely-used pesticide atrazine, culminating a multi-year assessment. Specific risk mitigation measures were described for potential human health concerns, however the document committed to future development of measures for mitigating ecological risks. As a follow-up, an addendum to the January document is being released. The addendum discusses ecological monitoring and risk mitigation within sensitive watersheds, the most current scientific information regarding potential effects of atrazine on amphibians and recent scientific work about the potential association between atrazine exposure and the incidence of prostate and other cancers.

Specifically to target monitoring of ecologically vulnerable watersheds, the manufacturers of atrazine are required to monitor residue levels in 40 indicator watersheds that are representative of watersheds that may be vulnerable to contamination where atrazine is regularly used. If monitoring indicates an exceedance of a level of concern in a watershed, the company will work to remediate the watershed consistent with the Clean Water Act’s total maximum daily load (TMDL) program and appropriate requirements under the federal pesticide law. If this remediation is not sufficient, EPA may take further action to mitigate risks from atrazine and will consider as appropriate, benefits of atrazine use in the particular watershed. This innovative and protective approach was jointly developed by EPA, atrazine manufacturers, the U.S. Department of Agriculture and grower groups to provide an early alert system in watersheds where atrazine may be a concern. This model approach may in turn be used to address similar concerns in other watersheds. Since issuing the IRED, EPA has carefully evaluated and received scientific peer review of studies regarding possible developmental effects on amphibians exposed to low doses of atrazine. These data do not provide evidence to show that atrazine produces a consistent, reproducible effect on amphibian development. An independent science peer review panel convened in June supported the Agency’s conclusions and recommended that more data be generated to evaluate this potential relationship. Generation of this data is underway. Based on the available scientific work on the potential association between atrazine and cancer, the Agency does not find any studies that would lead the Agency to conclude that potential cancer risk is likely from exposure to atrazine. However, EPA will continue to review new studies on this issue and plans to convene another independent Scientific Advisory Panel concerning atrazine and its potential association with carcinogenic effects.

EPA’s work on atrazine is based on a thorough review of an extensive body of the best available scientific data and studies, has been subject to participation by the public and stakeholders, and has undergone independent scientific peer review. Atrazine is used on a variety of crops and nonagricultural applications. It is being reviewed as part of EPA’s ongoing program to evaluate older pesticides to ensure that they meet current health and environmental safety standards, including the health protective measures, called for in the Food Quality Protection Act (FQPA). In addition to the significant accomplishment represented by this action on atrazine, today’s action fulfills an obligation to the Natural Resources Defense Council (NRDC) and others under a consent decree. Extensive information on EPA’s review of atrazine is available at: .