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Pesticide News Story: Chlorpyrifos Preliminary Volatilization Assessment Suggests Bystander Risks of Concern; EPA Requests Comment to Address Uncertainties

For Release: February 8, 2013

The EPA is requesting comment on a preliminary evaluation of the potential risks to children and other bystanders from volatilization of chlorpyrifos from treated crops. While there are uncertainties associated with EPA’s preliminary assessment, the available data indicate that vapor phase chlorpyrifos may be emitted from treated fields at levels resulting in exposure to children and others who live, work, attend school or otherwise spend time nearby.  In some circumstances, these bystanders may be exposed to chlorpyrifos and/or the transformation product chlorpyrifos-oxon at concentrations that could cause adverse effects. The chlorpyrifos preliminary volatility assessment , guide to commenters , and related documents are available in docket EPA-HQ-OPP-2008-0850 at www.regulations.gov.

If the final, more refined, chlorpyrifos volatility assessment indicates that risks are similar to those found in the preliminary evaluation, the EPA anticipates that it may be necessary to take action to reduce bystander risks. With more information, however, the agency’s preliminary assessment could be refined and result in lower exposure and risk estimates.

To assist the EPA in refining the preliminary volatilization assessment during the comment period, the agency is requesting information and data in several areas, including methods for assessing volatility, or assessing and characterizing the effects of inhaled chlorpyrifos. A Guide to Commenters includes a list of questions on which the agency is seeking comment. The EPA will carefully consider all comments as well as any additional information or data provided in a timely way before revising the assessment.

The preliminary evaluation of the potential risks from volatilization of chlorpyrifos supplements the EPA’s June 2011 preliminary human health risk assessment for the registration review of chlorpyrifos , and July 2012 spray drift assessment . The chlorpyrifos volatilization assessment includes approaches that the agency has used previously to assess inhalation exposures of fumigant pesticides  . The assessment also is consistent with recommendations of the December 2009 FIFRA Scientific Advisory Panel meeting on the scientific issues associated with field volatilization of conventional pesticides. 

The EPA is reviewing chlorpyrifos to ensure that it continues to meet the statutory standard for registration and can be used without causing unreasonable adverse effects to human health or the environment. An organophosphate insecticide, chlorpyrifos is used to control insect pests on a variety of food crops and non-food sites.

The EPA’s preliminary volatilization assessment is also responsive to a petition filed by the Natural Resources Defense Council and the Pesticide Action Network North America, which requested that the agency revoke all tolerances and cancel all registrations for chlorpyrifos. The agency’s interim responses to the petition including a recent January 25, 2013 response are available in docket EPA-HQ-OPP-2007-1005  at www.regulations.gov.

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