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FIFRA SAP To Consider and Review Chlorpyrifos Biomonitoring Data in Three-Day Meeting
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By Lisa M. Campbell and Timothy D. Backstrom

On March 8, 2016, the U.S. Environmental Protection Agency (EPA) published a notice in the Federal Register stating that the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) Scientific Advisory Panel (SAP) will hold a three-day meeting scheduled for April 19-21, 2016, from 9:00 a.m. to 5:00 p.m. (EDT) to consider and review Chlorpyrifos:  Analysis of Biomonitoring Data.  The meeting will be held at EPA’s Conference Center, Lobby Level, One Potomac Yard (South Bldg.), 2777 S. Crystal Drive, Arlington, Virginia 22202.  The meeting will be webcast.  More information will be posted online.

The notice states that written comments are encouraged through April 5, 2016, and that requests for oral comments are encouraged to be submitted by April 12, 2016, but that both may be submitted until the date of the meeting.  Nominations of candidates to serve as ad hoc members of FIFRA SAP for the meeting are requested on or before March 23, 2016.

In this meeting, EPA states that it will solicit comment from FIFRA SAP on the evaluation of biomonitoring data using the physiologically-based pharmacokinetic (PBPK) model, proposed points of departure and extrapolation/uncertainty factors, and examples of a proposed approach to use the PBPK model to simulate internal doses of chlorpyrifos from current exposure patterns from drinking water, food, and worker exposure.  The FIFRA SAP has been reviewing the human health effects of chlorpyrifos since 2008.  The notice states that “at this point in time, the Agency’s analysis of biomonitoring data from the cord blood collected as part of the Columbia University epidemiology studies has progressed to a point where peer review would be useful” and that “[s]pecifically, the Agency has done additional characterization of the pharmacokinetic profile of simulated exposures from oral and dermal exposures using the PBPK model.”

The notice states that in 2008 and 2012, the FIFRA SAP “cautioned EPA against using the biomonitoring data from epidemiology studies … to directly derive points of departure due to uncertainties associated with a lack of knowledge about timing of indoor chlorpyrifos applications and a single measure of exposure (cord blood).”  The 2012 FIFRA SAP recommended that EPA use the PBPK model to further characterize the dose estimates in the epidemiology studies.

The notice states that EPA would have preferred to complete its analysis of the available biomonitoring prior to commencing rulemaking, but that the timing for the proposal was directed by the U.S. Court of Appeals for the Ninth Circuit, which ordered EPA to respond to an administrative petition to revoke all chlorpyrifos tolerances by October 31, 2015.

More information on the Ninth Circuit case is available in our blog item Circuit Court Grants Writ of Mandamus Requiring EPA to Act on Petition to Ban Chlorpyrifos.

Commentary

EPA’s decision to utilize biomonitoring data that was collected as part of the Columbia University epidemiology studies for chlorpyrifos to derive proposed points of departure for risk assessment purposes will be highly controversial.  If EPA proceeds to use biomonitoring data from epidemiological studies to derive points of departure for risk assessment purposes, the implications for all pesticide product risk assessments could be significant.  Whether EPA can defensibly do so from both a scientific and legal standpoint is a subject that will likely be debated strongly.  All pesticide registrants should monitor these developments closely.