Bergeson & Campbell, P.C. serves small, medium, and large pesticide product registrants and other stakeholders in the agricultural and biocidal sectors, in virtually every aspect of pesticide law, policy, science, and regulation.

By Lisa M. Campbell, Timothy D. Backstrom, and James V. Aidala

On June 10, 2015, the Ninth Circuit Court of Appeals granted a petition for a writ of mandamus for a petition filed by Pesticide Action Network North America and Natural Resources Defense Council in 2007. That petition requested that EPA cancel all registrations and revoke all tolerances for the insecticide chlorpyrifos. An order granting a writ of mandamus is unusual, and indicates that the Court is impatient about what it perceives to be the slow pace of review by the U.S. Environmental Protection Agency (EPA). The petitioners previously sought such a writ in 2012, and the Court denied that request without prejudice in 2013. EPA took action in 2012 that addressed seven out of the ten issues originally raised by the petitioners, and the Court found in 2013 that the time taken by EPA to address the petition was “not unreasonable in light of the complexity of the issue.” On March 26, 2015, EPA wrote to the petitioners stating that it intends to deny their petition to cancel registrations and revoke tolerances for chlorpyrifos. EPA bases this anticipated decision on a new human health risk assessment incorporating a physiologically based pharmacokinetic-pharmacodynamic (PBPK-PD) model that allows EPA to estimate human risk directly rather than extrapolating from animal data. Based on this model, EPA determined that label changes are needed to mitigate certain occupational exposures and localized drinking water exposure, and has requested comment on these findings.

EPA counsel represented during oral argument in the case that EPA could complete its review of the comments and take action on the petition by mid-September 2015. In response, the Court has issued an order directing EPA either to submit a status report by June 30, 2015, stating whether EPA intends to finalize its preliminary denial, or whether EPA has decided instead to grant the petition in whole or in part. If the petition will be denied, EPA must issue the final denial decision by September 15, 2015.

Commentary

The schedule imposed by the Court order is demanding, but it is likely that EPA will make every effort to meet it. The Court did not require EPA to respond to all of the comments on the risk assessment, or to determine what mitigation measures will ultimately be required, by the September deadline. Although EPA would normally prefer to complete all related tasks and to compile a comprehensive administrative record before issuing the final decision denying the petition to cancel chlorpyrifos, that would be very challenging to do in this instance. The comment period for the current risk assessment closed on April 30, 2015, and EPA must evaluate and respond to detailed comments on a complex assessment, one which has some important issues subject to serious dispute by the affected registrants. For example, Dow Agrosciences LLC submitted a 130 page set of comments on April 29, 2015, in addition to comments received from the general public, users of the pesticide, and other interested parties. If EPA determines it will proceed with its stated intent to deny the petition to cancel, this action may precede the mitigation measures that EPA imposes based on the chlorpyrifos risk assessment and the comments on that assessment. Nevertheless, because the petitioners are likely to challenge the denial decision as well, EPA will need to prepare an adequate explanation of the reasons for the denial and to expedite the related administrative actions to the extent that is practicable.


 

By Lisa M. Campbell, James V. Aidala, and Susan Hunter Youngren, Ph.D.

Along with the release of the revised human health risk assessment for chlorpyrifos, in late December 2014, the U.S. Environmental Protection Agency (EPA) filed a Response to the Petition for a Writ of Mandamus that the Pesticide Action Network North America and the Natural Resources Defense Council, among others, filed in September 2014 in the U.S. Court of Appeals for the Ninth Circuit. This action is the latest of several brought to try to achieve a ban of chlorpyrifos and a revocation of food tolerances for chlorpyrifos.

EPA’s December 2014 response states that its “thorough consideration of these issues will inform its ultimate decision whether to leave in place the tolerances for chlorpyrifos or cancel chlorpyrifos registrations, and a full record will facilitate any subsequent judicial review of those decisions.”

On January 7, 2015, EPA included in a status report to the court the issuance of its revised human health risk assessment. EPA indicated that currently it plans to “issue a proposed rule to revoke tolerances in early 2015 or a final denial order in mid-2015.”

It is not clear what EPA implies by stating that it could issue a proposed tolerance revocation in “early 2015” when the assessment of chlorpyrifos has only recently been released, availability announced in the Federal Register on January 14, 2015, and there is an open comment period on the document scheduled to close on March 16, 2015. Any action would presumably take some time, given the need to review submitted comments and formulate a response. Preparing any regulatory action would take some additional amount of time, especially since registrants of chlorpyrifos products can be expected to have substantial comments on the documents.
 


 

By Lisa M. Campbell, James V. Aidala, and Susan Hunter Youngren, Ph.D.

The U.S. Environmental Protection Agency’s (EPA) January 5, 2015, release for public comment of the revised human health risk assessment of chlorpyrifos (http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPP-2008-0850-0195) reflects another step taken to implement its new spray drift and volatilization policies. These policies were long in the making and the subject of significant discussion and controversy over the years. EPA, with this assessment, has also taken a very public step to implement its controversial policy, announced in December 2009, to apply, effectively, Food Quality Protection Act (FQPA) risk assessment techniques to pesticide uses not subject to FQPA, as part of its commitment to environmental justice.

The spray drift and volatilization policies were discussed in an October 2014 webinar and discussed in our September 17, 2014, memorandum. EPA’s Revised Risk Assessment Methods for Workers, Children of Workers in Agricultural Fields, and Pesticides with No Food Uses, issued in 2009, is discussed in our December 8, 2009, memorandum.

Spray Drift and Volatilization

EPA had been assessing spray drift and volatilization for chlorpyrifos for a number of years, and many of the EPA-derived spray drift and volatilization tools are based on chlorpyrifos data. The January 5 assessment updates the assessment conducted in 2011. This document assesses both potential risks to workers (mixing/loading/applying and re-entry) as well as potential risks to residents (bystanders and food/water consumption). The bystander assessment uses the new tools that EPA released in Spring 2014 to assess potential risks from volatilization and spray drift (as discussed in the B&C webinar). The buffer zones EPA had previously estimated to mitigate spray drift are reduced in the new assessment. The risks noted in the assessment were for workers and specific water areas.

FQPA Risk Assessment Methods Use for Non-FQPA Assessment

In addition to implementing its spray drift and volatilization policies, EPA also assessed exposure in a manner that appears intended to implement the 2009 policy that was the subject of much concern when released for public comment. In that policy, EPA stated its intent to apply risk assessment techniques developed in implementing FQPA’s “extra safety factor” to any pesticide product’s risk assessment, regardless of whether it falls under FQPA, “so long as application of the risk assessment technique is consistent with good scientific practice and is not otherwise prohibited by law.” EPA stated then that this would include “using an additional safety/uncertainty factor to protect children,” as well a number of other factors. EPA announced this policy originally as part of its commitment to considerations of environmental justice.

The chlorpyrifos assessment is based on a physiologically-based, pharmacokinetic-pharmacodynamic (PBPK-PD) model to estimate the toxicologic Points of Departure (POD), thus deriving different toxicological values of concern based on the age, sex, and duration of exposure. The PBPK-PD model is also used to estimate intra-species uncertainty factors (UF), as there is no need for inter-species factors because the model estimates human red blood cell (RBC) acetylcholinesterase/cholinesterase (AChE/ChE) inhibition. Based on the PBPK-PD model, a 10X intra-species factor was used for females of childbearing years whereas it was 4X for all other groups assessed.

The worker of concern in the assessment is defined to be a female of childbearing years due to concern of not only RBC AChE/ChE inhibition, but also the potential for neurodevelopmental effects as seen in epidemiological studies. The epidemiological studies are controversial because there have been many questions about actual exposure to chlorpyrifos, particularly as two studies measured a biomarker that can be seen from exposure to other organophosphates (OP). The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) Science Advisory Panel (SAP) reviewed EPA’s assessments of these studies in 2008 and 2012. The SAP concluded that “chlorpyrifos likely played a role” in the observed neurodevelopmental outcomes. EPA determined that based on the weight of evidence (WOE) from animal studies and epidemiological studies, reduction of the 10x “FQPA Safety Factor (SF)” was not appropriate. The residential dietary assessments were compared to a Margin of Exposure (MOE) of 100 (10X FQPA SF x 10X intra-species factor) for women and an MOE of 40 (10X FQPA SF x 4X intra-species factor) for all other ages. The occupational assessments were compared to an MOE of 100 for women and 40 for all other age groups (with no explanation of the reasoning behind those values).

This is noteworthy and should be examined closely because EPA has effectively used an additional “FQPA factor” as a safety factor for occupational assessments. EPA stated in its press release announcing the assessment that potential restrictions may be necessary to protect workers and water.

Next Steps

There is a 60-day comment period for this document, which are due on or before March 16, 2015. Among the issues commenters are likely to address include:

     Use of the PBPK-PD model to estimate PODs;

     Use of the PBPK-PD model to estimate intra-species uncertainty factors;

     Use of the epidemiological data; and

     Use of a 10X SF for occupational exposure.

The full impact of this assessment is not yet clear, but it raises many issues of interest to registrants.
 


 
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