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 and Timothy D. Backstrom
 
On July 5, 2016, a three judge panel of the U.S. Court of Appeals for the Ninth Circuit issued a brief opinion denying a petition for review of a U.S. Environmental Protection Agency (EPA) order in which EPA declined to “immediately adopt interim prohibitions on the use of toxic drift-prone pesticides … near homes, schools, parks, and daycare centers or wherever children congregate.”  Petitioners Pesticide Action Network North America (PANNA), United Farm Workers, and Pineros y Campesinos Unidos del Noroeste (PANNA, et al.) filed an administrative petition in 2009 asking EPA to conduct pesticide-specific drift assessments and to impose interim buffer zones to protect children from pesticide drift.
 
The Circuit Court agreed with EPA’s contention that the petitioners do not have jurisdiction to review the reregistration and tolerance determinations previously made by EPA pursuant to the Food Quality Protection Act (FQPA), because such challenges are now time barred.  EPA agreed with the petitioners that it should consider potential risks from spray drift as part of the registration review under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA).  The petitioners argued that EPA had thereby acknowledged legal error when it previously reregistered food-use pesticides, but EPA has vigorously contested that premise.  In 2014, EPA issued a proposal describing the methodology for assessing risk from pesticide drift that EPA will use prospectively in making registration review decisions.
 
The petitioners requested that EPA adopt interim relief by imposing uniform buffer zones for all pesticides that are registered for application by ground sprayers, broadcast, or aerial application, and that may cause certain human health effects.  EPA rejected this request for across-the-board buffer zones as unscientific and inefficient and likely to result in a misallocation of EPA resources.  The Circuit Court concluded that “substantial evidence” supports EPA’s decision to deny this interim relief, stating that “[t]he record suggests that the risk of exposure to pesticide draft depends on a number of factors, including pesticide toxicity, the method of application, the size of pesticide droplets, and weather conditions,” and “adequately supports EPA’s conclusion that the imposition of uniform buffer zones is not the most ‘scientifically appropriate’ method for mitigating the risk of exposure to pesticide drift.”


Commentary


The Circuit Court has clearly recognized that uniform buffer zones like those sought by the petitioners would not be “scientifically appropriate.”  While this decision is both welcome by industry and constructive, the evaluation of potential exposure and risk from pesticide drift during the registration review process for individual pesticides will likely remain controversial.

More information on EPA’s spray drift policy is available in our memorandum Spray Drift and Volatilization: Issues to Navigate Carefully as EPA Develops Registration Review Decisions.


 

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.
 


 

By Susan Hunter Youngren, Ph.D.

On October 15, 2014, the Office of Pesticide Programs (OPP) announced a voluntary program to document the effectiveness of agricultural pesticide spray application technologies on reducing pesticide spray drift. Under the Drift Reduction Technology (DRT) Program, agricultural equipment manufacturers would conduct (or make arrangements for a testing facility to conduct) studies to determine the percent drift reduction according to a verification protocol. Once completed, the manufacturer would submit the study to the U.S. Environmental Protection Agency (EPA) for review and evaluation. As verified, these reductions could then be quantitatively credited in the environmental risk assessments used to develop the drift reduction measures appearing on the label of the pesticide product. EPA will then review the manufacturers’ studies and, based on these data, it will assign spraying devices a rating on a four-star scale:

* Four stars: Device can reduce spray drift by 90 percent or more.

* Three stars: Device can reduce spray drift by between 75 percent to 89 percent.

* Two stars: Device can reduce spray drift by between 50 percent to 74 percent.

* One star: Device can reduce spray drift by between 25 percent to 49 percent.

* No stars: Device can reduce spray drift by less than 25 percent.

EPA allows pesticide manufacturers to include labeling on their products that contain dual-use instructions, one for farmers using devices that have received stars through the DRT program and another for those using devices that do not have a DRT rating.
 


 

By:  Lisa M. Campbell and Susan Hunter Youngren, Ph. D.

Spray drift and volatilization issues increasingly are significant issues in pesticide product risk assessments. Earlier this year, the U.S. Environmental Protection Agency (EPA) issued drafts of key guidance documents, which focused on issues that were key in the chlorpyrifos petition response, and more recently, at least one registration review decision that reflects current and still evolving EPA policy on spray drift and volatilization issues.

How potential for spray drift and for volatilization are identified and then managed are likely to be key elements of ongoing and future risk assessments underlying forthcoming EPA registration and reregistration, with significant potential impact on these decisions. Registrants should monitor closely the policies, EPA decisions implementing them, and their potential impact on their products, particularly given the public interest in these issues.

The EPA documents issued in the past eight or so months are significant, particularly given the years of controversy and difficulty in past attempts to propose a clear and “simple” definition of “drift.” The perception by some advocacy groups is that EPA is not adequately addressing alleged harms posed by drift, and resulting appeals for court intervention will undoubtedly complicate the matrix of considerations influencing EPA’s policy. These reasons alone make monitoring the development of these policies critical for registrants.