EPA Revises Relative Potency Factors for the Cumulative Risk Assessment

 

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Subject:  EPA Revises Relative Potency Factors for the Cumulative Risk Assessment
Date:     Wed, 24 Apr 2002 18:01:44 -0400
From:      Stephen Tvedten <steve@getipm.com>
Organization:     Get Set Inc. (www.getipm.com)

To:     Paul Helliker <phelliker@cdpr.ca.gov>
          Director, State of California, Department of Pesticide Regulation 

cc:    Christine Whitman whitman.christine@epa.gov

IN THIS EPA UPDATE:

EPA Revises Relative Potency Factors for the Cumulative Risk Assessment of the Organophosphate Pesticides

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EPA Revises Relative Potency Factors for the Cumulative Risk Assessment of the Organophosphate Pesticides

The Environmental Protection Agency (EPA) has revised the relative potency factors (RPFs) included in the Preliminary Cumulative Risk Assessment for the Organophosphate Pesticides (OPs) after refining RPF calculations and analyzing new toxicology data for several OPs.  EPA discussed the refined statistical procedures at the February 5-7, 2002 meeting of the FIFRA Scientific Advisory Panel (SAP), and the SAP supported the proposed refinements. The revised RPFs incorporate a more accurate statistical model that better reflects the toxicology data used in the RPF calculations. Relative potency factors allow levels of exposure to different OPs to be expressed in terms that are considered toxicologically equivalent. The Agency will use these factors to determine the combined risk presented to human health from all the OPs identified in the risk assessment. Therefore, the accuracy of the potency factors are critical to the success of the assessment.  In addition, EPA has calculated RPFs for chlorethoxyphos, phostebupirim, and profenofos, to replace default RPFs utilized in the Preliminary Cumulative Risk Assessment. EPA has also received additional toxicology data for disulfoton, fenamiphos, phosalone, tetrachlorvinphos, and tribufos.  New data for omethoate, the oxon metabolite of dimethoate, have been utilized to calculate an RPF not included in the Preliminary Risk Assessment.  The Points of Departure (PODs) were not impacted by the revisions.

To access a table containing the revised RPFs, go to: http://www.epa.gov/pesticides/cumulative/pra-op/rpf_final.htm

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