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By Timothy D. Backstrom

On February 3, 2020, the U.S. Environmental Protection Agency (EPA) issued a Federal Register notice announcing the availability of an interim registration review decision for glyphosate.  EPA previously issued a proposed interim registration review decision (PID) for glyphosate for comment in April 2019.  At the time EPA issued the glyphosate PID for comment, EPA also issued a draft human health risk assessment and a preliminary ecological risk assessment for glyphosate.  After reviewing the comments received concerning these assessments, EPA has not made any revisions to either assessment.  EPA has determined that there are no dietary, residential, bystander, or occupational human health risks of concern associated with glyphosate use.   EPA has also determined that there are some potential risks to plants, birds, mammals, and invertebrates from glyphosate use, but that these can be appropriately mitigated by label changes requiring enforceable spray drift management measures and adding a warning concerning the potential hazards to non-target organisms.  EPA also has proposed some new measures to manage the development and spread of herbicide-resistant weeds.  EPA has generally retained the proposed labeling changes identified in the PID, except for some modest adjustments to the proposed language concerning droplet size restrictions and swath displacement restrictions for aerial applications, and removal of spray drift advisory language for airblast application.

Despite considerable publicity recently concerning purported carcinogenic risks for glyphosate, including allegations that human exposure to glyphosate can be linked to non-Hodgkin's lymphoma, EPA has determined that glyphosate is not likely to be a human carcinogen and has steadfastly adhered to this basic conclusion.  EPA made this determination for glyphosate after convening a meeting of the FIFRA Scientific Advisory Panel (SAP) to evaluate the carcinogenic potential of glyphosate in 2016.

The general purposes of the PID process are to allow EPA to move forward with aspects of the registration review process that are essentially complete, and to adopt interim risk mitigation measures, even though some of the actions required prior to a final registration review decision are not yet complete.  As in the case of most recent PIDs, EPA states that it has not yet made a complete determination concerning potential effects or any required consultation for glyphosate under the Endangered Species Act (ESA), nor has it made a determination for glyphosate under the Endocrine Disruptor Screening Program (EDSP).  In addition, EPA is considering a pending petition to prohibit preharvest use of glyphosate on oats, and to reduce the tolerance for glyphosate in oats, that was filed in 2018 by the Environmental Working Group and others.  This petition is predicated on the potential carcinogenicity of glyphosate.  Finally, EPA is still evaluating the question of whether additional data will be needed to evaluate properly the potential effects of glyphosate use on pollinators.  

More information on glyphosate and EPA’s interim registration review decision is available here.

Commentary

EPA's interim registration review decision for glyphosate is predicated on EPA's prior determination that the best available scientific data do not substantiate the claims that glyphosate may be a human carcinogen.  As discussed above, the potential carcinogenicity of glyphosate was thoroughly evaluated by the FIFRA SAP in 2016.  EPA's determination after that review that glyphosate is not a carcinogen has also been supported by other pesticide regulatory authorities.  Nonetheless, EPA's view conflicts with a cancer classification decision for glyphosate by the World Health Organization (WHO), and with some recent tort case decisions that were based on the premise that there is a credible linkage between glyphosate exposure and human cancer.  EPA recently announced that it would not permit or approve any cancer warning statements for inclusion in glyphosate labeling (including any statements that may be required pursuant to California's Prop 65) because EPA believes that such statements are false or misleading and would therefore cause the pesticides to be "misbranded."

It appears probable there will be continued litigation based on the purported carcinogenicity of glyphosate, along with various proposals to ban or restrict glyphosate use.  The pending petition to restrict use of glyphosate on oats that was filed by EWG, et al., is expressly predicated on the potential carcinogenicity of glyphosate, so it appears probable that this petition will ultimately be denied by EPA.  Nonetheless, unless WHO decides to reverse or modify its classification determination, or the courts determine that the recent tort awards for glyphosate users cannot be scientifically substantiated, the battles over the claimed carcinogenicity of glyphosate may persist for years.

More information on glyphosate issues is available on our blog under keyword glyphosate.


 

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.


 

By Lisa M. Campbell, Lisa R. Burchi, and James V. Aidala

On May 6, 2019, the U.S. Environmental Protection Agency (EPA) announced it was releasing its Proposed Interim Registration Review Decision (PID) for glyphosate acid and its various salt forms.  84 Fed. Reg. 19782.  In the PID, EPA states that it “did not identify any human health risks from exposure to any use of glyphosate” but did identify “potential risk to mammals and birds” within the application area or areas near the application area and “potential risk to terrestrial and aquatic plants from off-site spray drift, consistent with glyphosate’s use as a herbicide.”  Even with these potential risks, the PID states that “EPA concludes that the benefits outweigh the potential ecological risks when glyphosate is used according to label directions” and proposes certain risk mitigation strategies, including:

  • “To reduce off-site spray drift to non-target organisms, the EPA is proposing certain spray drift management measures” with specific spray drift mitigation language to be included on all glyphosate product labels for products applied by liquid spray application;
  • “To preserve glyphosate as a viable tool for growers and combat weed resistance, the EPA is … proposing that herbicide resistance management language be added to all glyphosate labels” and to require measures “for the pesticide registrants to provide growers and users with detailed information and recommendations to slow the development and spread of herbicide resistant weeds”;
  • Inclusion on labels of a non-target organism advisory statement to alert users of potential impact to non-target organisms; and
  • “EPA is also proposing certain labeling clean-up/consistency efforts to bring all glyphosate labels up to modern standards.”

EPA states that these measures were discussed with glyphosate registrants, who do not oppose the proposed risk mitigation measures outlined in the PID.

The public can submit comments on EPA’s proposed decision at www.regulations.gov in Docket Number EPA-HQ-OPP-2009-0361.  Public comments are due by July 5, 2019.  In addition to the PID, EPA is also posting to the glyphosate docket EPA’s response to comments on glyphosate’s usage and benefits (dated April 18, 2019), EPA’s response to comments on the human health risk assessment (dated April 23, 2018), and EPA’s response to comments on the preliminary ecological risk assessment (dated November 21, 2018). 

This PID was issued shortly after the Agency for Toxic Substances and Disease Registry’s announcement on April 8, 2019, of the opening of a docket on the draft toxicological profile for glyphosate.  84 Fed. Reg. 13922.  ATSDR seeks comments and additional information or reports on studies about the health effects of glyphosate for review and potential inclusion in the profile.  Comments are due by July 8, 2019.

Commentary

EPA’s PID and related documents, along with ATSDR’s draft profile and the peer review which will follow, can be expected to become part of the larger debate about the potential risks of glyphosate.  In 2017, EPA evaluated the carcinogenic risk of glyphosate, and released its draft human health and ecological risk assessments.  See our December 19, 2017, blog item "EPA Releases Draft Human Health and Ecological Risk Assessments for Glyphosate for Public Comment" for more information. 

EPA’s PID is interesting not only for the conclusions EPA reached following its review of data submitted by registrants in response to a data call-in (DCI) and following the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) Scientific Advisory Panel’s (SAP) meeting to consider and review scientific issues related to EPA’s evaluation of the carcinogenic potential of glyphosate, but for the issues that remain to be addressed.  Notably, EPA states that it has not considered the petition filed on September 27, 2018, to reduce glyphosate’s tolerance because the petition was filed after the comment period for the human health and ecological risk assessments closed.  Instead, EPA plans to post the petition in the glyphosate docket and address the petition concurrently with the development of the Interim Registration Review Decision.

In addition, EPA has not in the PID or related documents addressed issues regarding its Endangered Species Act (ESA) assessment or its Endocrine Disruptor Screening Program (EDSP) activities.  EPA states it intends to complete an assessment of risk to ESA-listed species prior to completing its final registration review decision for glyphosate, and that it also will make an EDSP determination under Federal Food, Drug, and Cosmetic Act (FFDCA) Section 408(p) before completing its registration review.  EPA also notes that it continues to evaluate risks to pollinators, and that if it determines “that additional pollinator exposure and effects data are necessary to help make a final registration review decision for glyphosate, then the EPA will issue a DCI to obtain these data.”  Although there are significant areas that remain to be resolved, EPA issued the PID “so that it can (1) move forward with aspects of the registration review case that are complete and (2) implement interim risk mitigation.”

More information on glyphosate issues is available on our blog.