By Heather F. Collins, M.S. and Barbara A. Christianson

On November 4, 2020, the U.S. Environmental Protection Agency (EPA) published a notice in the Federal Register announcing the release of an updated list of pests of significant health importance for public review and comment.  85 Fed. Reg. 70146.

EPA, in coordination with the Centers for Disease Control and Prevention (CDC) and the U.S. Department of Agriculture (USDA), identifies pests of significant public health importance, and in coordination with the Public Health Service, develops and implements programs to improve and facilitate the safe and necessary use of chemical, biological, and other methods to combat and control such pests of public health importance.  According to EPA, the list serves as a tool for private and public organizations, including local or state governments, departments of public health, pesticide registrants, and non-governmental organizations, when making decisions and plans about future public health actions.

Since this list’s original publication in 2002, new vector-borne diseases have been identified and pests that had been previously thought of as benign or nuisance pests have been found to impact adversely public health.  EPA, CDC, and USDA collaborated to update the list to incorporate significant changes regarding vector-borne diseases and related research, and eliminate gaps or ambiguities in the current pests list.

EPA states in the notice that the draft Pesticide Registration (PR) Notice 2020-X more precisely describes both the pests and expected public health impacts and adds several new pests (the brown dog tick) and public health impacts (Zika fever and coronaviruses like SARS-CoV-2) and that other pests have been renamed or grouped with similar species or removed altogether (hobo spider).

Draft PR Notice 2020-X describes the groups of pests and their potential impact on public health as follows:

• Arthropods: The listed arthropods may cause asthma or trigger allergies, contaminate food, irritate skin, cause direct injury, or carry diseases such as epidemic typhus, trench fever, epidemic relapsing fever, malaria, encephalitis (St. Louis, Eastern, Western, West Nile, and LaCrosse), yellow fever, dengue fever, and many others.
• Vertebrates: The listed organisms have the potential for direct human injury and can act as disease reservoirs for rabies and other diseases. The rats and mice include those that spread rodent-borne diseases and contaminate food for human consumption.
• Microorganisms and acellular particles:  This category includes listed bacteria, fungi, protozoans, viruses, virusoids, and prions. The microorganisms and acellular particles listed in this category cause diseases such as COVID-19, cholera, meningitis, Legionnaire’s Disease, and many others.

The complete list of pests is identified in draft PR Notice 2020-X in Appendix A.

EPA states that the list does not affect the regulatory status of any registration or application for registration of any pesticide product.

Comments on the draft PR Notice are due on or before January 4, 2021, in Docket EPA-HQ-OPP-2020-0260.

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By Timothy D. Backstrom and James V. Aidala

On December 18, 2019, the Office of Pesticide Programs (OPP) of the U.S. Environmental Protection Agency (EPA) issued for comment a Proposed Interim Decision (PID) in the ongoing registration review process for each of the three registered triazine herbicides: atrazine, propazine, and simazine.  EPA will allow 60 days for comment on each of these triazine PIDs, but the specific comment deadline will only be established after EPA has published notice concerning the proposed interim decisions in the Federal Register.  EPA can utilize an “interim registration review decision” under 40 C.F.R. Section 155.56 whenever it is not yet ready to complete the registration review process, but EPA has nonetheless completed sufficient review to determine that new or interim risk mitigation measures are needed or that additional data or information should be submitted to complete the review.  For each of the three triazine herbicides, EPA is proposing to impose specific risk mitigation measures for particular registered uses to mitigate potential health and environmental risks.  For each triazine herbicide, EPA is not yet ready to make a final registration review decision because EPA has not made findings in the Endocrine Disruptor Screening Program (EDSP) or an effects determination under the Endangered Species Act (ESA).  Several key factors that will affect the final registration review decision for each of the triazine herbicides are discussed below.

Common Factors for Triazine Risk Assessment

There are several common factors to consider with regard to the triazines risk assessment.  These include:

1. Atrazine, propazine, and simazine are all included in the chlorotriazine chemical class.  EPA has determined that these three herbicides, along with three specific chlorinated metabolites, share a common mechanism of toxicity, so human health risks from all of these substances are being assessed by EPA together through one cumulative triazine risk assessment. The contribution of each product to aggregate human risk differs because of somewhat dissimilar use patterns. The combining of risks resulting from use of each triazine means, however, that it may be necessary for EPA to coordinate the ultimate registration review decisions for the three active ingredients.
2. As part of the ecological risk assessment for each triazine herbicide, EPA plans to make an effects determination for potentially vulnerable species under the ESA, which in turn will determine whether it is necessary for EPA to consult with the Fish and Wildlife Service or the National Marine Fisheries Service (the Services) concerning potential impacts of each active ingredient and relevant metabolites on endangered or threatened species.  Atrazine, propazine, and simazine are all included in a stipulated settlement between the parties in Center for Biological Diversity et al. v. EPA et al. No. 3:11 cv 0293 (N.D. Cal.), and EPA agreed in that stipulated settlement to set August 14, 2021, as the deadline for EPA to make a nationwide effects determination for each active ingredient, and to request any required consultation with the Services, under ESA Section 7(a)(2).
3. EPA states that the predominant human health effect of concern for all three of the triazine herbicides and their chlorinated metabolites is potential suppression of the luteinizing hormone (LH) surge, which is considered to be both a neuroendocrine and a developmental effect.  Atrazine and simazine were both included on List 1 for screening testing under the EDSP required by the Food Quality Protection Act (FQPA) amendments.   All of the required Tier 1 screening assays for each of these substances are complete and have been evaluated by EPA, but EPA has not yet made human health or environmental findings under the EDSP.  The EDSP screening testing has not been completed yet for propazine.

Risk Mitigation Measures

Each PID proposes specific risk mitigation measures intended to address potential human and environmental risks identified by the EPA risk assessments.

For atrazine, the PID includes the following measures to mitigate aggregate human risk:

• Reduce the permissible application rates for use of granular and liquid formulations on residential turf.
• Require additional personal protective equipment (PPE) and engineering controls for certain uses.
• Restrict aerial applications to liquid formulations only.
• Limit backpack sprayer applications to landscape turf to spot treatment only.
• Prohibit pressurized handgun application to certain commodities.

To mitigate ecological risks, the atrazine PID proposes to require various spray drift reduction measures, to add a non-target advisory statement to labeling, and to adopt a nationwide stewardship program.

For propazine, the PID proposes to cancel the greenhouse use to mitigate aggregate human risk.  Ecological risks would be mitigated by proposing to require various spray drift reduction measures and by adding a non-target advisory statement to labeling.

For simazine, the PID includes the following measures to mitigate aggregate human risk:

• Cancel simazine use on residential turf.
• Require additional PPE and engineering controls for certain uses.
• Limit pressurized handgun applications to certain commodities to spot treatment only.

Ecological risks would be mitigated by proposing to require various spray drift reduction measures and by adding a non-target advisory statement to labeling.

Commentary

In each of the PIDs for the triazine herbicides, EPA has focused its efforts on adopting mitigation measures which should be efficacious in reducing human and ecological risks without materially impairing the availability of the products in question for key agricultural uses.  In some instances, the PID documents explicitly state that the product registrants have agreed to proposed changes.  An EPA Pesticide Program Update dated December 19, 2019, that discusses the interim decision for atrazine includes statements of support from several grower groups.

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By Lisa M. Campbell and Timothy D. Backstrom

On September 9, 2019, the U.S. Environmental Protection Agency (EPA) Office of Pesticide Programs (OPP) published a notice in the Federal Register announcing the availability of, and an opportunity for comment on, a document describing an “interim process” that OPP’s Environmental Fate and Ecological Effects Division is currently using to evaluate potential synergistic effects of mixtures of pesticide active ingredients on non-target organisms. As part of a lawsuit challenging the 2012 decision by EPA to register Enlist Duo Herbicide (a combination of 2,4-D and glyphosate), OPP scientists learned that patent applications for some registered pesticide products included claims that particular combinations of active ingredients provide “synergistic” control of target species.  Although EPA was not at that time considering potential synergies in assessing the risk for ecological effects on non-target organisms, based on the patent application claims regarding synergy for Enlist Duo, EPA decided to request that the reviewing court vacate its registration decision and remand the application for Enlist Duo for further study of these effects and any measures that might be needed to mitigate the risk to non-target organisms.  This decision sparked much controversy, and many in industry were concerned that patent application claims were not being correctly interpreted by EPA for the category of pesticide products at issue.

The new document released by EPA for review and comments is entitled: “Process for Receiving and Evaluating Data Supporting Assertions of Greater Than Additive (GTA) Effects in Mixtures of Pesticide Active Ingredients and Associated Guidance for Registrants.”  EPA states that it “has generally been applying this interim process since 2016.” The process described in the document has five steps: (1) registration applicants must search for any granted patents that include synergy (GTA) claims for combinations of pesticides; (2) applicants must review the patent claims and supporting data for relevance to ecological risk assessment; (3) applicants must report to EPA all effects testing data from the relevant patents; (4) applicants must do a statistical analysis (using a method prescribed by EPA) to determine whether any observations of GTA effects are statistically significant; and (5) EPA will review all submitted information to decide whether it should be utilized in ecological risk assessment.

In the Federal Register notice, OPP lists five specific areas pertaining to the interim risk assessment process described in the document on which it is requesting comment:

• Are there technical aspects of the interim process that warrant change? If so, what changes are recommended?
• What aspects of the process could be applied to the evaluation of open literature sources of GTA effects pesticide interactions?
• Should EPA consider standardizing a more detailed search and reporting approach, and how should EPA do that?
• Should EPA continue the evaluation process as described in this document? If so, what performance metrics (e.g., number of evaluations) should EPA consider before deciding the utility of this approach?
• What applicant burden is associated with the activities described in this memorandum, including compiling, analyzing, and submitting the information? Specifically, does an estimate of 80-240 hours of burden per applicant cover the respondent burden associated with the interim process?

When the National Research Council (NRC) evaluated the importance of toxicological interactions between pesticide active ingredients in 2013, the NRC concluded that such interactions are rare, but that EPA should nonetheless consider such interactions when the best available scientific evidence supports such an evaluation.  In the current Federal Register notice, EPA makes it clear that it is uncertain concerning the utility for risk assessment of the information used by manufacturers to support synergistic effects claims in pesticide patents.  According to EPA, 24 applicants for new registrations have submitted patent data to date, but only three of these submissions contained information that indicated a need for further testing and no submission ultimately led to any adjustment of the ecological risk assessment.  At this juncture, EPA will continue collecting patent data that may be pertinent to GTA effects, but when it has sufficient experience upon to base a general policy it may either continue or improve this process or discontinue it after explaining why.

Commentary

When EPA requested that the reviewing court vacate and remand the registration EPA had granted for Enlist Duo, the parties seeking judicial review located data in the patent applications that EPA had not previously seen or reviewed and that EPA believed could possibly be pertinent to potential adverse effects on non-target plants.  EPA concluded that it should revisit the decision based on the additional data.  Although EPA decided to request vacatur and remand, the applicant Dow AgroSciences had arguably followed all of the procedures then in place, because FIFRA Section 3(c)(5) allows EPA to waive data requirements pertaining to efficacy, and EPA typically registers pesticide product that are not intended to protect public health without any independent evaluation of efficacy data.  Nevertheless, in general EPA may choose to evaluate pesticidal efficacy data; such circumstances in the past often involved cases where EPA was required to consider whether pesticide benefits are sufficient to outweigh identified risks.  In the Enlist case, EPA determined that it should do so where potential synergy in pesticidal efficacy is pertinent to evaluating ecological effects on non-target species.

What EPA must decide now is how often efficacy data that has been deemed adequate by the Patent and Trademark Office to support a patent for a new pesticide mixture will have any material significance in the context of ecological risk assessment.  Before EPA makes a determination whether or not patent data has sufficient pertinence to continue requiring routine collection and evaluation of such data, EPA has decided it is prudent to afford all stakeholders an opportunity to comment on whether EPA has been asking the right questions.

All comments on the draft document must be submitted no later than October 24, 2019.

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By Jason E. Johnston

On September 4, 2019, the U.S. Environmental Protection Agency’s (EPA) Office of Pesticide Programs’ Environmental Fate and Effects Division (EFED) announced that the next Environmental Modeling Public Meeting (EMPM) will be held on October 16, 2019.  The EMPM is a semi-annual public forum for EPA, pesticide registrants, and other stakeholders to discuss current issues related to modeling pesticide fate, transport, and exposure for risk assessments in a regulatory context.

In a press release to the public, EPA indicates that the topics covered at the October meeting will include sources of usage data (relating to the actual application of pesticides, in terms of the quantity applied or units treated); spatial applications of usage data; model parameterization; extrapolation of usage data to fill in gaps; temporal variability of usage; and updates on ongoing topics.  Presentations concerning the incorporation of pesticide usage data into environmental exposure and ecological risk assessments will also be included.

Registration is required. Requests to participate in the meeting must be received on or before September 23, 2019, as noted in the Federal Register notice.

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By Jason E. Johnston

On August 13, 2019, the U.S. Environmental Protection Agency (EPA) published a notice in the Federal Register announcing a four-day meeting of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) Scientific Advisory Panel (SAP) will be held November 19-22, 2019.  The meeting location will be announced in the future on the FIFRA SAP website.  The title of the SAP meeting is “Approaches for Quantitative Use of Surface Water Monitoring Data in Pesticide Drinking Water Assessments.”  Pesticide registrants have long advocated for the opportunity to use monitoring data in drinking water assessments in place of estimates generated using current modeling approaches.  It is expected that EPA will present work that the Environmental Fate and Effects Division (EFED) has completed to permit use of surface water monitoring data.

The Federal Register Notice also requests nominations for ad hoc reviewers with particular expertise related to the particular issues to be addressed by this panel.  Nominations are to be submitted on or before September 12, 2019.

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