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, Jason E. Johnston, M.S., and James V. Aidala

On May 25, 2017, the U.S. Environmental Protection Agency (EPA) announced the release of ecological risk assessments for four neonicotinoid active ingredients for public comment as well as the Registration Review Update for Four Neonicotinoid Insecticides (Update).  82 Fed. Reg. 24113.  The ecological risk assessments are:

EPA states that public comments “could address, among other things, the Agency’s risk assessment methodology and assumptions applied to its draft risk assessments, such as its methodology for estimating colony-level risk to bees from exposure to bee bread.”  Comments on the three ecological risk assessments are due by July 24, 2017

The main focus of the Update document is EPA’s efforts to harmonize the risk assessment and management of the four neonicotinoids during registration review.  EPA has identified additional pollinator exposure data and pollinator toxicity data needs; registrants have committed to producing the needed data, and most of the data will be submitted in 2017.  EPA plans to produce final pollinator risk assessments for both agricultural and non-agricultural uses in 2018.  Release of non-pollinator risk assessments (i.e., aquatic organisms, terrestrial mammals, and birds) is planned for 2017.  Human health risk assessments are also scheduled to be issued in 2017.  EPA has stated that mitigating risk from the uses of all neonicotinoids may be considered for all four compounds at the same time to ensure consistent risk management and to prevent unnecessary shifts in usage between the compounds without a reduction in risk.  EPA intends to release final pollinator assessments and proposed interim decisions for registration review for all four neonicotinoids in 2018.

Commentary

From the EPA website, the following general statement summarizes what EPA has found so far:

  • The assessments for clothianidin, thiamethoxam, and dinotefuran, similar to the preliminary pollinator assessment for imidacloprid showed:  most approved uses do not pose significant risks to bee colonies.  However, spray applications to a few crops, such as cucumbers, berries, and cotton, may pose risks to bees that come in direct contact with residue.

To some degree, it is reassuring that widespread adoption of the neonicotinoid products appears not to be an overwhelming or altogether unanticipated risk to pollinators.  For insecticides, that foliar spray applications could be harmful is not good news, as any direct contact of an insect (bees) and insecticides usually is not good for the health of the insect. 

Another point some may find reassuring is that EPA has not found seed treatment with neonicotinoid products to be of significant risk.  This is ironic to some degree, since one of the fundamental assumptions not long ago among many beekeepers was that the seed treatment products were a singular and significant cause of the increase in colony decline and loss. 

EPA’s description of the registration review status of these products also indicates that a great volume of additional data concerning possible pollinator risks is due to arrive over the next six to 18 months.  Obviously, the results of these additional studies will fundamentally inform the EPA risk assessment conclusions.  At the same time, one legacy of the Obama Administration in this space, the development of state Manage Pollinator Protection Plans (MP3), also will be impacted by what EPA discovers from this volume of soon-to-arrive data.

Until then, and until the new political leadership of the agency indicates any direction on pollinator issues, it is unclear whether the pollinator issue will remain one of the priority issues for program attention, or be folded into the general timeline and normal course or registration review over the next few years.  


 

By Jason E. Johnston, M.S.

On May 31, 2017, the U.S. Environmental Protection Agency (EPA) announced the release of its Food Contact Sanitizing Solutions Model (FCSSM), a pesticide risk assessment model that has been developed to “estimate indirect dietary exposure to components of sanitizing solutions used in commercial settings.”  EPA states that “the model offers guidance for estimating exposure where there may be inadvertent transfer of residue to edible items prepared or transported on surfaces treated with these pesticides.”  The model consists of spreadsheets that automatically calculate dietary exposure and risk estimates based on data entered by the user.  The model estimates exposures to antimicrobial active ingredients listed under 40 C.F.R. § 180.940(b) and 40 C.F.R. § 180.940(c), where 940(b) includes uses in dairy processing equipment and food processing equipment and utensils, while 940(c) excludes dairy processing equipment.  FCSSM does not apply to active ingredients listed under 40 C.F.R. § 180.940(a), which are used on food contact surfaces in public eating places as well as dairy and food processing equipment.  For this case, EPA’s established methodology remains in place.  Compared to the simple calculation method used previously for these use scenarios, the major new feature of the FCSSM is the separate calculations of both acute and chronic dietary exposures for the general U.S. population and eight subpopulations.  EPA also released a user guide that provides background information on the model and familiarizes users with the inputs required to run the model.

More information about the FCSSM as well as other models used for pesticide risk assessments is available on EPA’s website


 

By James V. Aidala and Margaret R. Graham

On January 12, 2017, the U.S. Environmental Protection Agency (EPA) released its Policy to Mitigate the Acute Risk to Bees from Pesticide Products (Mitigation Policy) which describes methods for addressing acute risks to bees from pesticides.  EPA states that this Mitigation Policy is “more flexible and practical than the proposed policy” that was issued on May 29, 2015, and it has “made modifications to its approach with the goal of better targeting compounds that pose an acute risk, and with the goal of reducing potential impact of this effort on growers.”  EPA states that it will use its Tier 1 acute risk assessment to, in part, determine the products that trigger concerns about pollinator risk that the label restrictions are intended to address.  EPA will begin implementing this Policy in 2017 by sending letters to registrants describing steps that must be taken to incorporate the new labeling.  More information on the Mitigation Policy, including its supporting documents, and EPA’s response to comments submitted on the proposed policy, is available on www.regulations.gov under Docket ID EPA-HQ-OPP-2014-0818.

Also on January 12, 2017, EPA published preliminary pollinator-only risk assessments for the neonicotinoid insecticides clothianidin, thiamethoxam, and dinotefuran, and an update to its preliminary risk assessment for imidacloprid, published in January 2016.  EPA states that the preliminary assessments for clothianidin, thiamethoxam, and dinotefuran are similar to the preliminary pollinator assessment for imidacloprid, in that they showed that “most approved uses do not pose significant risks to bee colonies,” but “spray applications to a few crops, such as cucumbers, berries, and cotton, may pose risks to bees that come in direct contact with residue.”  As for the updated imidacloprid assessment, EPA states that is looked at potential risks to aquatic species, and identified some risks for aquatic insects.  Interested parties will have 60 days to comment on the preliminary risk assessments after notice is published in the Federal Register.  In terms of comments, EPA states that it is especially interested in getting input from stakeholders “on the new method for assessing potential exposure and risk through pollen and nectar.”  Links to risk assessment dockets for each individual insecticide are available on EPA’s website under Schedule for Review of Neonicotinoid Pesticides.  EPA states it is hopes to release the final neonicotinoid risk assessments by mid-2018.

Commentary

The revised Mitigation Policy has been long in coming since it was first released over eighteen months ago.  The delay in revising its approach reflects the complexity of the comments submitted, and EPA’s deliberateness in more finely crafting its policies, given the passage of time and other considerations.  This revised policy contains more flexibility and explicit discussion of the need for exceptions to blanket requirements in response to some of the comments received on the earlier proposal.  There remains significant public and regulator concern about the possible impacts on pollinators from pesticide use, however, there is currently less of a manic tone to EPA’s statements and actions.

For example, when discussing how EPA will approach changing the labels of the affected universe of pesticide products, there is a much less onerous tone and no specific deadlines for registrants to submit revised labels “or else.”  (The 2013 directives to registrants included demands for thousands of revised labels to be submitted within six weeks “or else” -- EPA would take “appropriate action” under FIFRA.)  EPA reminds us all that it retains authority to impose these new requirements broadly, a statement that will strike some as regulatory overreach, but the tone and approach is more in line with past EPA “guidance” about how it will approach a new or revised regulatory concern.   

Similar to what EPA previously concluded about imidacloprid, where that assessment concluded that the most controversial use -- corn seed treatments -- did not indicate a risk concern, EPA did include in its summary about the other three neonicotinoid pesticides that:

  • The assessments for clothianidin, thiamethoxam, and dinotefuran, similar to the preliminary pollinator assessment for imidacloprid showed:  most approved uses do not pose significant risks to bee colonies.  However, spray applications to a few crops, such as cucumbers, berries, and cotton, may pose risks to bees that come in direct contact with residue.

This might unfairly be summarized as:  after years of regulatory analysis EPA has concluded that if insecticides come into direct contact with insects, there is likely to be a risk to the exposed insect. 

This conclusion would be too simplistic since EPA and other regulatory bodies have expressed concern about what unintended exposures to insecticides might cause, and more generally the possibility of colony level impacts on honeybee and other pollinator populations from pesticide use.  Some critics will continue to insist that EPA broaden its regulatory approach to more than just pesticides used for crops under contracted pollinator services.  The broader issue of pesticide drift and possible impacts on non-target species will continue to be a concern for all pesticides.

Perhaps the more deliberate consideration of needed data generation and assessment that seems to be the current approach will allow both more refined regulatory controls if needed, and a reduction in the sometimes hot rhetoric which has accompanied the pollinator issues.

Lastly, although this revised Mitigation Policy and the three new preliminary assessments are not unexpected next steps as part of the ongoing registration review program for pesticides, given their very late release -- less than ten days before the arrival of a new Administration -- some might question whether this is part of the “midnight regulations” pushing the political agenda of the outgoing Administration.  The new leadership may revise what has been released, and may come to different conclusions about any needed restrictions.  That said, the issue of whether certain pesticides are having a dangerous impact on honeybee populations will continue to be a concern for regulators both in the U.S. and globally.


 

By J. Brian Xu, M.D., Ph.D., DABT®  and Margaret R. Graham

Like so many other regulatory programs in China, pesticide regulations are changing.  At the 8th China High-Level Forum on Pesticides, Ying Ji, Chief Agronomist of the Institute for the Control of Agrochemicals, Ministry of Agriculture (ICAMA), stated that the future of pesticide regulation in China will see more emphasis placed on industrial development, registration security, the application of more risk assessment techniques, and will focus more on reducing the burden of procuring registrations for minor use crops.  In China, the vast majority of registrations are for major crops and only a few registrations have been issued for minor crops.  The Ministry of Agriculture also intends to prepare a "List of Pests and Pesticide Shortage for Minor Crops.”

Jun Yang, Director of the Efficacy Division, ICAMA, summarized recent trials and registrations of pesticides.  By the end of August 2015, China had a total of 33,029 registered pesticide products, an increase of 4,300 products when compared with 2013.  The total includes insecticides (12,812), fungicides (8,378), herbicides (7,807), and others including acaricides and plant growth regulators (4,032).  Insecticides were down 3 percent and fungicides and herbicides up 2 percent as a proportion of the total when compared with the total at the end of 2013.  The majority of registered products were issued for off-patent products.  The top ten active ingredients for which products were registered as of 2014 were reported to include:  the antifeedant, pymetrozine; the fungicides, azoxystrobin, tebuconazole and difenoconazole; the insecticides, thiamethoxam, emamectin-benzoate, avermectin and imidacloprid; and the herbicide, cyhalofop and glufosinate.  For more information on the report (which is available only in Mandarin), please e-mail Dr. Brian Xu at .(JavaScript must be enabled to view this email address).


 

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

In an opinion issued on September 10, 2015, the U.S. Court of Appeals for the Ninth Circuit vacated the U.S. Environmental Protection Agency’s (EPA) unconditional registration for the pesticide sulfoxaflor and remanded the matter to EPA to obtain further studies and data regarding the effects of sulfoxaflor on bees and bee colonies.  Sulfoxaflor is a new insecticide in the class of insecticides referred to as neonicotinoids, but its mechanism of action is distinct from other neonicotinoids.  The Petitioners in this case were various trade organizations representing commercial beekeepers, as well as some individual beekeepers.  The registrant Dow AgroSciences LLC (Dow) intervened in the action.

EPA granted an unconditional registration for sulfoxaflor on May 6, 2013, subject to a variety of risk mitigation measures, including a lower application rate, longer intervals between applications, and certain crop-specific label restrictions.  EPA had previously proposed to issue a conditional registration for sulfoxaflor in January 2013, citing pollinator data gaps that could be addressed by requiring Dow to conduct and submit further studies.  Under that proposal, use of sulfoxaflor would have been allowed at a reduced application rate during the time needed to complete data development.  The court found that the subsequent decision by EPA to register unconditionally sulfoxaflor was not supported by substantial evidence, as required by Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) Section 16(b), both because EPA failed to adhere to its own scientific methodology and because the rationale that EPA provided for granting an unconditional registration could not be reconciled with the analysis upon which EPA based its prior proposal to register conditionally sulfoxaflor.

EPA evaluated the potential risk to bees and bee colonies from sulfoxaflor use utilizing the Pollinator Risk Assessment Framework, a scientific risk assessment methodology developed after consultations between EPA, Canada’s Pest Management Regulatory Agency, and the State of California, and presented by EPA to the FIFRA Scientific Advisory Panel in 2012.  The court found that the rationale provided for EPA’s unconditional registration decision could not be reconciled with findings that EPA itself made using this methodology or with the rationale EPA provided for its prior proposal to issue a conditional registration.  EPA had decided it was necessary to proceed to Tier 2 of the pollinator risk assessment after reviewing risk quotients and residue data in Tier 1 of the assessment.  EPA found the available data for Tier 2 to be insufficient to allow indefinite use of sulfoxaflor, even at a reduced application rate.  The court could not reconcile this finding with the subsequent decision to grant an unconditional registration, even with the specified mitigation measures.  The court found that “given the precariousness of bee populations, leaving the EPA’s registration of sulfoxaflor in place risks more potential environmental harm than vacating it.”  The court stated that “EPA has no real idea whether sulfoxaflor will cause unreasonable adverse effects on bees, as prohibited by FIFRA.”

EPA argued that with a reduced application rate, the risk quotients and residue analysis in Tier 1  was “close enough” to sufficient to avoid the specified quantitative trigger for a Tier 2 analysis, thereby rendering any deficiencies in the available Tier 2 data irrelevant.  The court effectively stated in response that close enough is not good enough, citing another recent Ninth Circuit decision in which a risk concern that is triggered by a margin of exposure less than or equal to 1000 was held to be triggered when the margin was exactly 1000.  Thus, this court once again placed EPA on notice that it must follow its own methodology with precision, and that EPA cannot justify deviations from its own methodology by simply stating that it is exercising expert judgment.

Commentary

This is an unusual case because the registration of a new pesticidal active ingredient has been vacated on substantive as opposed to procedural grounds.  The court’s rationale reflects a lack of judicial deference to what EPA typically refers to as the scientific “weight of the evidence.”  While the term itself does not appear in the opinion, the court is insisting that EPA must follow its standard methodology without allowing for any deviations based on professional judgment.  Although in this instance the court has supported the position of opponents of pesticide use, judicial reluctance to accept scientific “weight of the evidence” conclusions could also make it harder for EPA to impose additional restrictions when new but inconclusive evidence appears.

This case could cause EPA to be more explicit in adding procedures to its standard analytic methodologies that allow deviations from the methodology based on professional judgment.  The case could also cause EPA to reconsider its recent reluctance to avoid issuing conditional registrations and its preference for unconditional registrations for new active ingredients.  In any case, decisions that afford EPA less discretion to use “weight of the evidence” reasoning when basing scientific conclusions on less than conclusive data or studies could have an impact on a number of EPA practices and policies involving interpretation of scientific data.


 

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

The Environment Protection Agency (EPA) extended the comment date on its draft guidance, Pesticide Cumulative Risk Assessment: Framework for Screening Analysis, in a Federal Register notice published on August 28, 2015.  EPA’s draft framework provides guidance on how the EPA will screen groups of pesticides for cumulative evaluation.  EPA proposes using a two-step approach, beginning with the evaluation of available toxicological information and, if necessary, followed by a risk-based screening approach.  This framework supplements the existing guidance documents for establishing common mechanism groups (CMG) and conducting cumulative risk assessments (CRA).  Additionally, EPA is also seeking comments on a draft copy of the human health risk assessment where the cumulative assessment was conducted in conjunction with pending actions for abamectin.

EPA has described a process that is data intensive and that requires sophisticated knowledge and modeling.  EPA acknowledges that “the level of refinement provided by this approach is not necessary or even feasible for all existing pesticide classes.”  The policy documents for conducting the first step in the process, “developing CMGs,” are still being refined.

This document provides the guidance for screening information to identify candidate CMGs and does not outline how actually to conduct CRAs.  Rather, this document relies on policies and principles provided in other documents found on the EPA cumulative risk assessment website.  These additional policies and principles were developed during the conduct of five CRAs for chemical groups such as the organophosphates and carbamates.

One of the major questions raised by the issuance of this document is the extent of the information that EPA will require for each chemical to determine if there are CMGs.  The five CMGs currently assessed have relatively well defined mechanisms of action.  It is not clear, however, what EPA will consider to be adequate justification that there are no other chemicals with the same mechanism of action for other chemicals of concern.

Requirements for EPA to determine and assess the risks of possible common mechanism of action among groups of similar pesticides was one of the most far-reaching new requirements imposed by the Food Quality Protection Act.  Some observers expected a larger impact on pesticide use than what has occurred to date; whether EPA’s new approach results in more groupings or otherwise leads to restrictions on more groups of pesticides remains to be seen.

Comments on the draft guidance are due September 28, 2015.  More information regarding EPA’s assessment of pesticide cumulative risk is available online.


 

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.