EPA sent a “Memorandum to the File” with the above-quoted title and dated October 22, 2019. This memo has been posted in the atrazine FIFRA registration review docket. According to the “Overview” in EPA’s memorandum:

“The purpose of this memorandum is to articulate EPA’s risk management approach for aquatic plant communities and anticipated timeline for completion of registration review for atrazine. While atrazine’s registration review is currently ongoing, the Environmental Protection Agency (EPA or the agency) has received over 100,000 public comments on the atrazine draft risk assessments, some concerns, and several inquiries related to registration review status and the level of regulation for aquatic plants. This memorandum provides additional context regarding EPA’s proposed regulatory levels for aquatic plants for atrazine, and memorializes EPA’s decision to use the concentration of 15 µg/L as a 60-day average for the purposes of determining the need for any potential mitigation to protect aquatic plant communities during Registration Review.”

EPA’s 15 ppb level replaces EPA’s originally proposed aquatic plant community equivalent level of concern (CELOC) of 3.4 ppb for atrazine. EPA’s

memorandum emphasizes the 2012 Science Advisory Panel’s criticism of EPA’s originally proposed 3.4 ppb CELOC and its corresponding COSM Database as a major reason why EPA has decided to use its new 15 ppb level. The proposed 3.4 was subject to many critical comments during the proposed rulemaking for EPA’s atrazine Ecological Risk Assessment.

No CELOC will be used during EPA’s ESA consultation with NOAA/NMFS and FWS on atrazine. EPA’s recent memorandum said this on page 5 about CELOCs and ESA consultation (emphasis added):

“Impact on the ESA Assessment Atrazine is one of the chemicals that is scheduled to have a Biological Evaluation (BE). EPA recently released the Proposed Revised Method for National Level Endangered Species Risk Assessment Process for Biological Evaluations of Pesticides for public comment and is currently reviewing that input for incorporation as appropriate. It is EPA’s intent to use this revised methodology after public input is incorporated to complete the BE for atrazine. In addition, the draft atrazine BE will be available for public comment prior to being finalized.

To more accurately represent where and to what extent a pesticide is likely to be applied, the proposed revised ESA methods include an approach for incorporating pesticide-specific usage data into the listed species consultation process and a probabilistic analysis to determine the likelihood of a species to be adversely affected by a pesticide. Although comments are being evaluated, the goal of the probabilistic analysis is to more fully capture and characterize the variability in the range of potential exposures and toxicological effects by utilizing the entire distribution of exposure and effects values. Under this approach, quantitative use of the CE-LOC will not be the basis for final effects determinations. The proposed method also incorporates a weight of evidence framework to distinguish those listed species that are likely to be adversely affected (LAA) from those that are not likely to be adversely affected (NLAA), based on criteria (e.g., dietary preferences, migration patterns, extent of range potentially exposed) associated with the likelihood that an individual will be exposed and affected.

EPA gave the following explanation of its future review plans for atrazine:

“The next step in registration review is to release the proposed interim decision, which may propose risk mitigation measures, if needed, along with the agency’s response to comments on the human health and ecological risk assessments and its use benefits and mitigation impact analysis. EPA anticipates publishing these documents in December 2019. There will be a 60-day public comment period associated with the proposed interim decision, and EPA will release an interim decision after consideration of the comments on the proposed interim decision.

In addition, EPA will make an Endangered Species Determination by 2021 pursuant to a joint stipulation filed on October 18, 2019 in Center for Biological Diversity et al. v. Environmental Protection Agency et al. (N.D. Ca) (3:11-cv-00293) requesting that the court enter the agreed upon partial settlement.”

Click here to read EPA’s entire memorandum.