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Phorate IRED Facts

EPA 738-F-00-014
February 2001

EPA has assessed the risks of phorate and reached an Interim Reregistration Eligibility Decision (IRED) for this organophosphate (OP) pesticide. Phorate is eligible for reregistration, pending a full reassessment of the cumulative risk from OPs.

Used primarily on a variety of field agricultural crops, phorate residues from food alone do not exceed the Agency's level of concern. However, for dietary risk from drinking water, based on modeling (SCI-GROW), the maximum estimated concentrations of phorate and metabolites (sulfoxide and sulfone) in groundwater are slightly greater than the Agency's Drinking Water Level of Comparison (DWLOC) for chronic drinking water exposure. Also, the estimated concentrations of phorate and its metabolites in surface water slightly exceed EPA's DWLOC for acute exposure. However, the conservative nature of the food assessment together with extensive risk mitigation proposed in this document lead the Agency to believe that the dietary risk from food and drinking water exposure for phorate and its degradates will be below the Agency's level of concern following implementation of mitigation measures. Phorate has no residential uses. With the implementation of certain risk mitigation measures, phorate's worker and ecological risks also will be below levels of concern for reregistration.

EPA's next step under the Food Quality Protection Act (FQPA) is to complete a cumulative risk assessment and risk management decision encompassing the OP pesticides, which share a common mechanism of toxicity. The interim decision on phorate cannot be considered final until this cumulative assessment is complete. Further risk mitigation may be warranted at that time.

EPA is reviewing the OP pesticides to determine whether they meet current health and safety standards. Older OPs need decisions about their eligibility for reregistration under FIFRA. OPs with residues in food, drinking water, and other non-occupational exposures also must be reassessed to make sure they meet the new FQPA safety standard.

The phorate interim decision was made through the OP pilot public participation process, which increases transparency and maximizes stakeholder involvement in EPA's development of risk assessments and risk management decisions. EPA worked extensively with affected parties to reach the decisions presented in this interim decision document, which concludes the OP pilot process for phorate.


Health Effects


Risk Mitigation

In order to support a reregistration eligibility decision for phorate, the following risk mitigation measures listed below are necessary. Although most of the mitigation measures are directed to a specific risk scenario (worker risk, ecological risk, or drinking water concern), some measures will reduce risk in more than one area of concern:

The OP Pilot Public Participation Process

The organophosphates are a group of related pesticides that affect the functioning of the nervous system. They are among EPA's highest priority for review under the Food Quality Protection Act.

EPA is encouraging the public to participate in the review of the OP pesticides. Through a six-phased pilot public participation process, the Agency is releasing for review and comment its preliminary and revised scientific risk assessments for individual OPs. (Please contact the OP Docket, telephone 703-305-5805, or see EPA's web site, Pesticide Reregistration Status.)

EPA is exchanging information with stakeholders and the public about the OPs, their uses, and risks through Technical Briefings, stakeholder meetings, and other fora. USDA is coordinating input from growers and other OP pesticide users.

Based on current information from interested stakeholders and the public, EPA is making interim risk management decisions for individual OP pesticides, and will make final decisions through a cumulative OP assessment.

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