Evaluating Conventional Pesticides: Recent Developments

Posted on Behalf of  Katie Gibbs, Ruth Hwang

In March, 2020, the U.S. Environmental Protection Agency (EPA) released the Revised Method for National Level Listed Species Biological Evaluations (BEs) of Conventional Pesticides, which updated the 2013 Interim Method that described a 3-Step Pesticide Consultation Process for pesticide Endangered Species Act (ESA) assessments. This Revised Method is “intended to produce both sustainable and scientifically sound risk assessment process to prepare pesticides BEs and identify species that may be affected by the subject pesticide” (EPA, 2020). Specifically, the Revised Method incorporated several recommendations: 1.) the recommendations from the National Research Council (NRC); 2.) EPA’s “lessons learned” during the first three pilot BEs (based on the Interim Method); public comments provided through stakeholder meetings; comments received during consultation with federally recognized tribes; and comments provided by U.S. Fish and Wildlife Service (FWS), National Marine Fisheries Service (NMFS), and the U.S. Department of Agriculture (USDA) (EPA, 2020).

As previously described in our blog Pesticides and Endangered Species, under Section 7(a)(2) of the ESA and 50 CFR Part 402, pesticides are assessed to determine whether their use would affect any threatened or endangered species or harm designated critical habitats (EPA, 2016a). The 3-Step Pesticide Consultation Process was first introduced in the Interim Methods with steps to determine:

(1) No Effect/May Affect;

(2) Not Likely to Adversely Affect (NLAA)/Likely to Adversely Affect (LAA); and

(3) Jeopardy/No Jeopardy and Adverse Modification/No Adverse Modification (EPA, 2013).

In the 2020 Revised Methods, Steps 1 and 2 are represented by the BE, while Step 3 is the Biological Opinion (BO) (EPA, 2020). Within each step, four components, including problem formulation, effects analysis, exposure analysis, and risk characterization, are applied. The 3-Steps and how they interconnect as part of the decision making process for registering a pesticide are briefly summarized in Table 1 and Figure 1 below.

Table 1. Overview of the 3-Step Section 7 Endangered Species Act Consultation Process


Step 1

Step 2

Step 3


Biological Evaluation

Biological Evaluation

Biological Opinion


Individual and field

Individual and field/landscape/watershed

Population and landscape/watershed


No Effect/May Affect

Not Likely to Adversely Affect/Likely to Adversely Affect

No Jeopardy/Jeopardy


Figure 1. The 3-Step ESA Consultation Approach (Based on a figure in the National Academies of Science National Resource Council (2013) Report).

The 2020 Revised Methods will be applied to all future EPA BEs for listed endangered species. By developing a methodical and standardized method, the EPA aims to effectively categorize pesticide, using the best available information, as ‘No Effect’ or ‘Not Likely to Adversely Affect’ an endangered species. Notably, the Revised Method for conducting BEs is not a regulation, and, as such, the BE process remains iterative. It will continue to evolve as the EPA gains experience conducting these assessments and as scientific methods continue to improve (EPA, 2020).

Cardno ChemRisk scientists have extensive professional experience evaluating the possible hazards and risks posed by chemicals, including pesticides. Related services and experience include: 1) Assessing  toxicological studies; and 2) Familiarity with EPA models used to assess pesticide risks to non-target species, including honeybees, plants, birds, and mammals, as well as endangered species. For more information on Cardno ChemRisk's capabilities, please contact Dr. Andrey Massarsky and Dr. Jordan Kozal.