Federal biological opinion clears path for continued atrazine use as EPA registration review advances.
The U.S. Fish and Wildlife Service (FWS) has concluded that atrazine, one of the most widely used herbicides in American agriculture, is not likely to jeopardize endangered or threatened species when used according to updated label requirements and conservation measures.
The decision, released as part of a final biological opinion under the Endangered Species Act (ESA), represents a significant milestone in the Environmental Protection Agency’s (EPA) ongoing registration review of the widely used crop protection product.
Key Findings from the Biological Opinion
FWS evaluated atrazine’s potential impact on hundreds of protected species and habitats across the United States. The agency determined that, while some species could experience localized or individual-level effects, those impacts would not rise to a level that threatens overall species survival or critical habitat integrity.
Specifically, the review examined over 500 listed species and more than 200 critical habitats, making it one of the most comprehensive pesticide consultations conducted in recent years.
“After incorporating conservation measures on the atrazine label, we found that the proposed registration is not likely to jeopardize the continued existence of listed species,” the agency stated in its findings.
Contrast with Earlier Federal Assessments
The conclusion marks a notable shift from earlier EPA biological evaluations released in 2021, which found that atrazine was likely to adversely affect more than 1,000 endangered species.
Under ESA procedures, such “likely to adversely affect” determinations trigger formal consultation with FWS. The final biological opinion reflects a broader analysis of population-level impacts rather than individual exposures, ultimately concluding that species viability would not be compromised.
Implications for U.S. Agriculture
Atrazine remains a cornerstone herbicide for American farmers, particularly in row crop production. It is widely used on crops such as corn, sorghum, and sugarcane, where it helps control annual grasses and broadleaf weeds.
The FWS finding is expected to support continued use and potential reauthorization of atrazine as part of EPA’s required 15-year review under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). [
Industry groups and manufacturers have emphasized the importance of atrazine for maintaining crop yields and managing herbicide resistance, noting that it remains a cost-effective tool in integrated weed management systems.
Regulatory Context and Next Steps
The atrazine review has been shaped by years of litigation and regulatory scrutiny. Environmental organizations previously challenged EPA findings, prompting additional consultation and a court-directed timeline for completion of the biological opinion.
With the FWS conclusion now finalized, the EPA can move forward in determining whether atrazine meets federal safety standards for continued registration.
The biological opinion also incorporates mitigation measures, including potential restrictions related to spray drift, runoff, and buffer zones, designed to reduce exposure risks to sensitive species and habitats.
Ongoing Debate and Industry Reaction
Despite the conclusion, the decision remains controversial. Environmental groups argue that atrazine poses risks to wildlife and water quality, citing its widespread presence in waterways and links to ecological and human health concerns.
Agricultural stakeholders view the findings as science-based and necessary for maintaining productivity in U.S. food systems.