On June 29, 2016, the U.S. Environmental Protection Agency (EPA) submitted a status report in the Ninth Circuit Court of Appeals case concerning a petition by Pesticide Action Network North America (PANNA) and the Natural Resources Defense Council (NRDC) to revoke the tolerances and cancel the registrations for chlorpyrifos.  The Court of Appeals issued an order on December 10, 2015, requiring EPA to take final action concerning the PANNA and NRDC petition no later than December 30, 2016.  To comply with an earlier order, EPA issued a proposed rule to revoke the tolerances for chlorpyrifos before it could complete a refined drinking water assessment or propose a new “point of departure” for chlorpyrifos based on biomonitoring data from an epidemiological study. 

EPA’s status report states that it has made “significant progress” towards meeting the December 30, 2016, deadline, but “extraordinary circumstances exist that make it impracticable for the Agency to meet the Court’s deadline.”  Based on these extraordinary circumstances, EPA has requested a six-month extension for final action on the petition. 

EPA notes that a proposed new point of departure was presented to the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) Scientific Advisory Panel (SAP), but was not favorably received.  At the same time, EPA states that the SAP “raised concerns about the approach EPA adopted in the Proposed Rule, namely that the continued use of acetylcholinesterase inhibition as the point of departure may not be sufficiently health protective.”  EPA infers that the SAP may be disposed to recommend a “hybrid approach,” but the written SAP report will not be issued until the end of July, 2016.

EPA states that it had planned to seek public comment on its refined drinking water assessment and new point of departure for chlorpyrifos immediately after the SAP meeting.  EPA now believes that it would be best to obtain the final SAP report before deciding how to establish a point of departure.  Accordingly, EPA proposes to seek comment on its refined drinking water analysis and analysis of the epidemiological data by early Fall 2016, and to take final action on the PANNA and NRDC petition by June 30, 2017.

Commentary

EPA expects that the refined drinking water assessment for chlorpyrifos will allow “tailored risk mitigation” that could eliminate one basis for the proposed revocation of chlorpyrifos tolerances.  In contrast, EPA’s concerns about the potential neurodevelopmental effects of chlorpyrifos may not be as readily addressed by risk mitigation.  If EPA decides either to retain the Food Quality Protection Act (FQPA) 10X safety factor for chlorpyrifos based on purported neurodevelopmental effects observed in epidemiological studies, or to adopt some “hybrid” risk assessment methodology for neurodevelopmental effects in response to the SAP recommendations, debate on the merits of doing so will likely be strong.  The status report does not appear to suggest that EPA is currently considering revisiting its general views on the chlorpyrifos epidemiological data; if EPA is not doing so, considerable continued debate on this issue is also likely.