The U.S. Environmental Protection Agency released proposed revisions to the agency’s September 2020 atrazine interim decision (ID) for public comment. The move was criticized by agricultural groups who have seen several disappointing crop protection regulatory developments in recent weeks. The Triazine Network says if changes are finalized by EPA it could put the key crop protection tool and today’s carbon-smart farming practices at risk.

The Federal Insecticide, Fungicide and Rodenticide Act requires EPA to periodically re-evaluate pesticides through registration review to ensure that risk assessments and pesticide decisions reflect the best available science. The ID in the registration review process allows EPA to begin implementing measures to mitigate risks of concern before a final decision is issued.

Atrazine is one of the most widely used herbicides in the United States. It is used to control broadleaf and grassy weeds in a variety of agriculture crops, such as field corn, sweet corn, sorghum and sugarcane. Atrazine is also used in non-agriculture settings, including nurseries, ornamentals and turf. EPA explains the herbicide is an important tool in agricultural production because it is economical, has a flexible use pattern, has long residual herbicidal activity, and is effective against a broad spectrum of weeds. Atrazine is also an important tool in herbicide resistance management, both in controlling weeds resistant to other herbicides and maintaining the effectiveness of other herbicides to control weeds. 

“To say growers are frustrated is an understatement. The science hasn’t changed since 2020, when EPA set the level of concern at 15 parts per billion. EPA is playing politics with this decision and should not adopt this ultra-low level of concern,” says Greg Krissek, Triazine Network co-chair and Kansas Corn Growers Association CEO.

Iowa farmer and National Corn Growers Association President Chris Edgington also expressed disappointment in EPA’s decision. NCGA warns if the new labeling requirements are finalized, it would impose arduous new restrictions and mitigation measures on the herbicide, limiting how much of the product farmers use. “We can feed and fuel the world and fight climate change, but we can’t do these things without modern farming tools, and atrazine is a tool that is critical to our work,” Edgington says.

Step back for atrazine registration

At issue is the aquatic ecosystem concentration equivalent level of concern (CE-LOC). In a published decision that concluded the registration review of atrazine in 2020, EPA set the atrazine CE-LOC at 15 parts per billion. Environmental activist groups retaliated with a lawsuit in the Ninth Circuit Court of Appeals. This opened the door for EPA to shift tactics and alter its decision. In action June 30, EPA proposed a return to a 2016 level of CE-LOC of 3.4 parts per billion, which would have “devastating impacts on farmers,” the Triazine Network says.

This is the concentration of atrazine that, when exceeded, presents a greater than 50% chance of negatively affecting an aquatic environment. The CE-LOC is based on effects to aquatic plant communities; however, by ensuring protection of primary producers, the CE-LOC is intended to also provide protection for the entire aquatic ecosystem, including fish, invertebrates and amphibians.  

In October 2020, EPA received a petition alleging that the agency violated its duties under FIFRA by issuing the atrazine ID without substantial evidence supporting the decision. In August 2021, EPA sought a voluntary partial remand in light of President Biden’s executive order on protecting public health and the environment and restoring a commitment to science and scientific integrity. On December 14, 2021, the Ninth Circuit Court of Appeals granted EPA a voluntary partial remand, which provided the agency the opportunity to reevaluate the policy decision to use 15 μg/L as the level of regulation for aquatic plant communities, EPA explains.  

The Triazine Network says EPA floated the 3.4 ppb number in a draft proposal in 2016 and received over 30,000 comments opposing the ultra-low level. In 2019, the agency stated in a regulatory update it would use the 15 ppb CE-LOC and solidified that number in the published 2020 Interim Registration Decision.

In its latest action, EPA says based on its review of the substantial evidence associated with the atrazine ecological risk assessment and a consideration of growers’ need for flexible and manageable mitigation measures, EPA is now proposing, for public comment, additional mitigation to protect aquatic plant communities. EPA is proposing the following measures for all atrazine labels in order to decrease atrazine runoff from treated fields: 

Additional mitigation options

In addition, EPA is proposing to add a “picklist” to labels that would require growers to select a combination of application rate reductions and/or runoff control measures when using atrazine in watersheds with atrazine concentrations that exceed the CE-LOC of 3.4 μg/L.

The number of runoff control practices from the picklist that a grower would be required to implement depends on the estimated atrazine concentration in the watershed where the field is located and that watershed’s vulnerability to atrazine runoff, as well as the grower’s selected application rate. The higher the application rate and the higher the estimated atrazine concentration in the watershed, the greater the number of mitigation practices that may be necessary.   

There are no picklist requirements for fields located in watersheds with predicted atrazine concentrations below 3.4 μg/L (approximately 82% of the total number of watersheds nationwide). 

Fields located in watersheds with predicted atrazine concentrations between 3.4-9.8 µg/L (approximately 8% of watersheds) would generally be required to choose 1-4 picklist requirements, depending on application rate, crop, region, and soil erodibility. 

Fields located in watersheds with predicted atrazine concentrations of above 9.8 µg/L (approximately 10% of watersheds) would have the highest level of required picklist mitigations to select. 

EPA says the picklist approach provides growers with the flexibility to select the runoff control practices that would be least burdensome to adopt. The practices a grower selects may depend on a variety of factors including crop, geographic region and field topography. The picklist mitigation requirements are tailored geographically, down to the watershed level, in order to focus the mitigation on the areas with the greatest risk and vulnerability.  

Farmers rely on atrazine’s long-lasting weed control, and it is especially important as an aid to help farmers successfully use sustainable farming practices like conservation tillage and no-till, the Triazine Network explains. Placing severe limits on atrazine will have broad implications considering that atrazine is a key component in over 90 herbicide mixtures farmers rely upon. Atrazine has been on the market for over 60 years. No herbicide has been studied more or has a longer safety record, they add.

“EPA’s proposal would render atrazine unusable for many farmers and force them to abandon carbon-smart no-till practices in key areas of the Midwest,” Krissek says. “While EPA is proposing mitigation measures for farmers to use in areas that would exceed the CE-LOC, our farmers are already concerned many of those methods won’t be viable on their farm. For example, one suggested method is to incorporate atrazine into the soil, which would end years, if not decades, of no-till practices on those fields.”

Public comment period now open

The public comment period is now open for the Proposed Revisions to the Atrazine Interim Registration Review Decision in the atrazine registration review docket ID number EPA-HQ-OPP-2013-0266 at www.regulations.gov. Public comments will be accepted for 60 days upon publication of the Federal Register notice.  

Krissek states, “We are urging farmers to oppose EPA’s regulatory tricks and submit comments to EPA during the 60-day comment period this summer.”

The latest development marks a step backward in EPA’s commitment to transparency and the use of the best available science, NCGA’s Edgington says. However, he notes that EPA listened to growers’ requests and agreed to additional scientific review. Edgington notes NCGA is committed to working with EPA in that process.  

After considering comments on the proposed revisions to the atrazine ID, EPA says it will determine if any changes are warranted to the proposed revisions and then release its decision on this re-evaluation. The agency also intends to seek external peer review of the risks to the aquatic plant community that underlies this proposed risk management strategy.

Before any part of this proposal is implemented, EPA must stand by its promises to convene a formal FIFRA Scientific Advisory Panel to specifically explore the scientific basis for the proposed CE-LOC revision and ensure high-quality research supports the proposal, the Triazine Network points out.

“EPA personnel told us the agency would convene a formal SAP to provide guidance on this matter. However, the news release and docket documents refer only to an ‘external peer review.’ That is not the same thing,” Krissek explains. “We urge EPA to publicly commit to convening a formal FIFRA Scientific Advisory Panel to advise the agency on this matter. This SAP incorporating the latest peer-reviewed studies is key to ensuring EPA’s proposed CE-LOC is supported by valid scientific evidence.”