US EPA intends to restrict chlorpyrifos use to protect bystanders

U.S. EPA is requiring significant reductions in application rates and mandatory buffers around sensitive sites to protect children and other bystanders who live, attend school, play, or otherwise spend time next to sites where chlorpyrifos is applied. To ensure timely implementation of the spray drift mitigation, EPA is taking steps to make sure that the new use restrictions appear on all chlorpyrifos agricultural product labels starting in late 2012. 

To increase protection for children and other bystanders, the lower application rates and other spray drift mitigation measures ensure that any chlorpyrifos exposure outside the application site will not reach harmful levels. Maximum aerial application rates are being significantly reduced from about 6 pounds per acre to about 2 pounds per acre. Other new mitigation measures include buffer zones for ground and aerial applications around sensitive sites such as residential lawns, homes, sidewalks, outdoor recreational areas, and all property associated with buildings typically occupied by people. 

As part of the agency’s ongoing registration review, EPA examined chlorpyrifos spray drift and potential bystander exposures using current scientific methods. EPA found that health risks from exposure to chlorpyrifos spray drift around treated fields can be lowered through the use of buffers and specific application methods. The buffer distances are greatest for aerial applications, which pose the highest risk. By adopting the new mitigation measures, applicators can effectively lower spray drift levels and reduce risks to bystanders.

EPA’s new mitigation measures also respond in part to a petition filed by the Natural Resources Defense Council and the Pesticide Action Network North America, which asked EPA to revoke all tolerances and cancel all registrations of chlorpyrifos. In a partial response addressing the first six of ten petition claims, EPA has found that none of the six claims warrants revoking tolerances or canceling registrations for chlorpyrifos at this time.

EPA’s response to three of the remaining four claims involves highly complex assessments using precedent-setting risk assessment methodologies. Consistent with the agency’s external peer review policy, EPA sought advice on these issues from the FIFRA Scientific Advisory Panel (SAP) at a meeting on April 10-12, 2012, and recently received the SAP’s final report, dated July 11, 2012. The agency will consider the panel’s comments in completing the petition response and final human health risk assessment for the chlorpyrifos registration review. EPA will address the risk issues necessary to respond to the petition in its entirety by December 31, 2012. EPA intends to complete the comprehensive chlorpyrifos human health risk assessment, including both its dietary risk assessment and occupational risk assessment, in 2014.

The petitioners’ fourth remaining claim, that EPA failed to incorporate inhalation routes of exposure, is partly addressed by the chlorpyrifos spray drift risk assessment and new spray drift use restrictions that the agency is announcing today.  The agency is continuing to assess potential exposure and risk from spray drift and volatilization following chlorpyrifos applications, taking into consideration the recently received comments from the SAP.  EPA will also address this claim fully, therefore, in its complete response to the petition in December 2012.

Chlorpyrifos is used widely for controlling insects on food crops including fruits, nuts, vegetables, and grains, and on non-food sites such as golf course turf, industrial sites, greenhouses, nurseries, sod farms, and wood products.  Public health uses include aerial and ground-based fogger treatments to control adult mosquitoes.  An organophosphate, chlorpyrifos can cause cholinesterase inhibition in humans; that is, it can over-stimulate the nervous system if there is sufficient exposure.