EPA Announces the Availability of the Final 4-CPA Registration Review Decision before the Registration Review Deadline

On September 28, 2026, the U.S. Environmental Protection Agency (EPA) released the Final Registration Review Decision for 4-chlorophenoxyacetic acid (4-CPA). 91 Fed. Reg. 61228. The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) mandates a periodic review of existing pesticide registrations every 15 years, referred to as registration review. During registration review, EPA determines whether a currently registered pesticide continues to meet FIFRA’s registration standard.

EPA Action

4-CPA is a synthetic auxin registered for use as a plant growth regulator (PGR) to restrict root growth during seed germination of mung beans (Vigna radiata). EPA evaluated the dietary, occupational, residential, and aggregate risks that may result from the currently registered uses of 4-CPA. EPA did not identify risks from the currently registered products containing 4-CPA. Under the Federal Food, Drug, and Cosmetic Act (FFDCA), EPA establishes pesticide tolerances (maximum residue limits) on food when it determines there is a “reasonable certainty that no harm will result from aggregate exposure to the pesticide residue” when used according to its label. EPA also considered the benefits of continued registration and found that this pesticide is useful in aiding in the production of desirable mung bean sprouts by limiting root growth.

EPA found no risks of concern to any non-target taxa from the continued registration of products containing 4-CPA. With limited human health and environmental exposure and no risks of concern, EPA determined that no risk mitigation is needed. EPA, however, has identified a label clarification to support EPA’s exposure assumptions that the product is “for indoor use only.”

EPA has made a no effects (NE) determination for direct and indirect effects to all federally listed endangered and threatened species and their designated critical habitats under the Endangered Species Act (ESA) for the FIFRA use pattern of 4-CPA to treat mung beans.

Under the Endocrine Disruptor Screening Program (EDSP), EPA has completed its FFDCA Section 408(p)(6)-related commitments and obligations “to ensure the protection of public health” for 4-CPA in this final decision.

Commentary

Currently, all registered uses are indoor uses. Based on 4-CPA’s limited human health and environmental exposure resulting in no risks of concern, it can be considered a lower risk pesticide. It is uncommon that EPA makes both the ESA and EDSP determinations in a final registration review decision. Since no human health or environmental risks of concern were identified for 4-CPA, EPA was likely able to address its obligations under ESA and EDSP completely in a timely (that is, efficient) manner. EPA commonly issues a registration review “interim” decision (ID) when it needs to conduct additional assessments, such as a biological evaluation for endangered species or endocrine screening, due to the complicated and time-consuming risk assessments and required coordination with the U.S. Fish and Wildlife Service (FWS) and the National Marine Fisheries Service (NMFS) for ESA determinations.

This final registration review decision was released prior to the October 1, 2026, deadline set forth in the Pesticide Registration Improvement Act of 2022 (PRIA 5). EPA has completed few registration review requirements for active ingredients under FIFRA to date and will need another statutory extension to do so. EPA has estimated there are approximately 800 active ingredient cases subject to the 2026 registration review deadline. EPA has indicated that resources (e.g., budget and staffing), registrant data generation and submission delays, scientific complexity, ESA and EDSP reviews, and completing cumulative risk assessments are all factors contributing to the delays in completing registration review decisions by this previously extended deadline.

The proposed draft framework in the 2026 Farm Bill would extend the registration review deadline to October 1, 2031, giving EPA time to complete its obligations under FIFRA. There is continued debate among industry stakeholders and non-governmental organizations (NGO) over the registration review deadline extension, and it remains unclear whether there is sufficient support for congressional approval of an extension. There is one fact that industry and the NGOs may agree upon — EPA does not currently have the resources and staff to complete its registration review obligations.