Data Requirements for Pyrethrins and Pyrethroids

EPA has determined that developmental toxicity studies (DNTs) previously required for pyrethroid insecticides do not adequately characterize potential susceptibility of the young. In a September 4, 2009 letter, we stated that registrants who have not fulfilled requirements for the DNT may instead cite six previously submitted pyrethroid DNT studies rather than conducting a full new study. We noted that other data may be needed to fully address the potential for increased susceptibility of young organisms to the pyrethroids, focusing on pyrethroid-specific effects related to the mode of action and pharmacokinetic characteristics of this class of compounds.

In a February 16, 2010 letter to the registrant and stakeholder community, EPA asked companies and other interested parties to voluntarily submit study protocols designed to better understand the potential susceptibility associated with pyrethroids. We reviewed proposals submitted and presented them to the FIFRA Scientific Advisory Panel (SAP) for comment at their July 23, 2010 meeting on Comparative Adult and Juvenile Sensitivity Toxicity Protocols for Pyrethroids. View meeting information and minutes

EPA has developed a science paper that discusses the DNT study and related data issues. View Pyrethroids: Evaluation of Data from Developmental Neurotoxicity Studies and Consideration of Comparative Sensitivity.

These documents are also available in pyrethroid docket EPA-HQ-OPP-2008-0331 at

Based on feedback from the SAP and the EPA, the industry research proposal was revised. Since late 2010, the Pyrethroid Human Health Risk Assessment (CAPHRA) has worked with academic scientists to develop assays and models to assess the potential for juvenile post-natal sensitivity to pyrethroids. The CAPHRA presented their research at a SAP on May 19.  Meeting information and minutes are posted on that Web page.

View overview information and current regulatory activities for pyrethrins and pyrethroids.