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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.


 

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

On October 13, 2017, the U.S. Environmental Protection Agency (EPA) announced that it had reached an agreement with Monsanto, BASF, and DuPont on measures “to further minimize the potential for drift to damage neighboring crops from the use of dicamba formulations used to control weeds in genetically modified cotton and soybeans,” and “new requirements for the use of dicamba ‘over the top’ (application to growing plants) will allow farmers to make informed choices for seed purchases for the 2018 growing season.”

EPA states that in a series of discussions, it “worked cooperatively with states, land-grant universities, and the pesticide manufacturers to examine the underlying causes of recent crop damage in the farm belt and southeast,” “sought extensive input from States and [U.S. Department of Agriculture (USDA)] cooperative extension agents from across the country, as well as the pesticide manufacturers, on the underlying causes of damage,” and “reviewed all available information carefully and developed tangible regulatory changes for the 2018 growing season.”

The label changes that certain registrants of dicamba products have agreed to impose additional requirements for "over the top" use of these products next year.  These new requirements include:

  • Classifying products as "restricted use," permitting only certified applicators with special training, and those under their supervision, to apply them; dicamba-specific training for all certified applicators to reinforce proper use;
  • Requiring farmers to maintain specific records regarding the use of these products to improve compliance with label restrictions;
  • Limiting applications to when maximum wind speeds are below 10 mph (from 15 mph) to reduce potential spray drift;
  • Reducing the times during the day when applications can occur;
  • Including tank clean-out language to prevent cross contamination; and
  • Enhancing susceptible crop language and recordkeeping with sensitive crop registries to increase awareness of risk to especially sensitive crops nearby. 

This announcement follows two compliance advisories issued by EPA in August 2016 and July 2017 on what EPA described as the high number of complaints received regarding crop damage from the alleged misuse of herbicides containing the active ingredient dicamaba.  EPA’s August 2016 compliance advisory stated that the Missouri Department of Agriculture received 117 complaints alleging misuse of pesticide products containing dicamba, and Missouri growers estimated that more than 42,000 acres of crops had been adversely affected.  Further, that similar complaints alleging misuse of dicamba products were received by Alabama, Arkansas, Illinois, Kentucky, Minnesota, Mississippi, North Carolina, Tennessee and Texas.  In the spring of 2016, EPA issued a proposal to register dicamba to control weeds in cotton and soybean that have been genetically engineered to tolerate dicamba.  In November 2016, EPA issued a conditional registration for dicamba on dicamba-tolerant cotton and soybean to Monsanto for its Xtendimax product; and EPA recently approved a label amendment made by Monsanto for Xtendimax which includes “additional restrictions further minimizing off-field movement of the active ingredient dicamba.”

EPA’s July 2017 compliance advisory states that by early July, EPA had received reports of hundreds of complaints to state agencies in Arkansas, Missouri, and Tennessee, a significant increase from 2016; lists the three new conditional registrations issued late last year (including Xtendimax); and states that only these new registered products may be lawfully applied over-the-top of growing soybeans and cotton.  It discusses what it describes as unlawful applications of dicamba products, and states that “[e]xcept for the new conditionally registered dicamba products, application of a dicamba product during either the cotton or soybean crop growing season is unlawful under FIFRA.”

EPA’s July 2017 compliance advisory further states that each of the conditionally approved dicamba herbicide products has labeling that provides mandatory directions for use, restrictions, and special precautions that must be followed, and that the labels of the new products require specific and rigorous drift mitigation measures to further reduce the potential for exposure from spray drift including:

  • No application from aircraft;
  • No application when wind speed is over 15 mph;
  • Application only with approved nozzles at specified pressures; and
  • Buffer zones to protect sensitive areas when the wind is blowing toward them.

Commentary

The reports of and concerns about potential damage to crops in connection with the application of dicamba illustrate a problem that has long been discussed, which is the potential for unintended impact when a pesticide that has been specifically designed for use with one or more crops that have been genetically engineered to be tolerant to the pesticide is applied in close proximity to other crops that do not share these tolerant characteristics. 

The dicamba case also illustrates the differing views on potential misuse issues.  Some observers have questioned whether all of the reported dicamba incidents were due to misuse or misapplication of the product.  Although the 2018 label changes are designed to mitigate the potential for damage to sensitive crops, some question whether some unanticipated or as yet not completely understood factor may be at play in some of the incident reports.  One issue raised by some researchers concerns potential unexpected volatility of the product even when applied according to the label directions by well-trained applicators.  The registrants have disputed this suggestion, but it is an area which will likely be more thoroughly researched over the next few growing seasons.

More information on EPA’s regulatory action on dicamba is available on EPA’s website.


 

By Lisa M. Campbell, James V. Aidala, and Carla N. Hutton

On March 25, 2016, the U.S. Environmental Protection Agency’s (EPA) Office of Inspector General (OIG) sent a memorandum to Jim Jones, Assistant Administrator, Office of Chemical Safety and Pollution Prevention (OCSPP), announcing that it plans to begin preliminary research to assess EPA’s management and oversight of resistance issues related to herbicide tolerant genetically engineered (GE) crops.  OIG states that its review will include the Office of Pesticide Programs (OPP), as well as other applicable headquarters and regional offices.  OIG’s objectives are to determine:

  1. What processes and practices, including alternatives, EPA has provided to delay herbicide resistance;
  2. What steps EPA has taken to determine and validate the accurate risk to human health and the environment for approved pesticides to be used to combat herbicide resistant weeds; and
  3. Whether EPA independently collects and assesses data on, and mitigates actual occurrences of, herbicide resistance in the field.

OIG states that the anticipated benefit of the project “is a greater understanding of herbicide resistance[,] which will lead to an enhancement of EPA’s herbicide resistance management and oversight.”

Commentary

Pesticide resistance is not a new issue and is one that EPA has affirmatively addressed when granting registrations for new products, GE or not, for some time.  In fact, that newer chemistries often have a more niche mode of action to reduce potential toxicity concerns has led some observers to speculate that greater resistance is one potential trade-off for the development of less toxic materials.

This “investigation” may appear to some to be a response to concerns raised by critics of GE crops generally and to a recent EPA decision to approve Enlist Duo herbicide, a new formulation of 2,4,D- and glyphosate designed to address the problem of weed resistance to glyphosate-tolerant crops.  Glyphosate tolerant crops were first approved some years ago, and their use was so broadly and readily adopted that issues have arisen with regard to potential resistance to some weed species.  EPA is currently expected to approve another GE strain, Dicamba-tolerant crops, to control glyphosate tolerant weeds.

To critics of GE crops, using more herbicides to control problems caused by what they claim is overuse of another herbicide is evidence of a troubling “pesticide treadmill,” which they believe should not have been allowed to occur in the first place.  Rebutting this criticism, others assert that resistance is a problem for all pesticides, not only genetically modified ones, and that with sufficient controls, resistance can be delayed, if not avoided.  Registrants point out that it is very much in their self-interest to take steps to avoid resistance to their products -- once that occurs, the market viability of the product is significantly reduced.


 

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

Center for Food Safety v. EPA is a case in the U.S. Court of Appeals for the 9th Circuit (9th Circuit) that consolidates two petitions for review of a decision by the U.S. Environmental Protection Agency (EPA) to register the new herbicide product Enlist Duo for use in six Midwestern states. A group of non-governmental organizations filed one of the petitions and the Natural Resources Defense Council (NRDC) filed a separate petition. Enlist Duo combines the active ingredients glyphosate and 2,4-D. The registrant Dow AgroSciences (Dow) has intervened in the case. The petitioners focus primarily on the purported failure of EPA to consider properly the effects of Enlist Duo on certain endangered species.

Each petitioner has now filed a motion to stay the EPA action registering Enlist Duo due to Endangered Species Act (ESA) challenges. The first stay motion filed by NRDC is based primarily on the risk to monarch butterflies, and that stay motion has now been fully briefed. The other petitioners filed a separate stay motion focusing on whooping cranes and Indiana bats, but they waited until two weeks after EPA and Dow filed their briefs opposing the first stay motion. Before either stay motion was filed, Dow filed a motion seeking transfer of the case to the D.C. Circuit Court of Appeals. Arguing that the two independent successive stay motions were abusive, Dow later filed a motion to hold the briefing on the second stay motion in abeyance, pending a ruling on its transfer motion.

The 9th Circuit denied Dow’s motion to hold the briefing on the second stay motion in abeyance only three days later. This procedural ruling does not dispose of the underlying transfer motion, but it does suggest that the court is not inclined to transfer the case. If the case is not transferred, the court will ultimately consider and rule on both pending stay motions. The court’s interim order does not suggest how it views the pending stay motions. The petitioners have a heavy burden to show both a substantial likelihood of success on the merits and irreparable harm to obtain the requested interim relief. EPA and Dow contend that the petitioners have not established either of these things. Overall, this ESA challenge to a new genetically modified organism (GMO) product may indicate a new front in the ESA litigation arena, since new products have generally not been challenged under ESA requirements. 2,4,-D itself is not a new herbicide, so this case is not quite a challenge to a totally new active ingredient; such a challenge was made recently in the case of cyantraniliprole. CBD, et al. v. EPA, No. 14-00942 (D.D.C. filed Oct. 10, 2014). Challenges to new active ingredients and GMO products, however, could threaten to hinder the introduction of new products into the marketplace.