EPA dicamba rule tracks Bayer's preferred options, records show

Federal courts have twice ordered the herbicide off market

The Environmental Protection Agency presented Bayer, manufacturer of the drift-prone weedkiller dicamba, with a menu of mitigation options during a May 2025 meeting and incorporated Bayer’s preferred choices into a proposed federal rule, internal agency documents released through litigation show.

The records, obtained in an ongoing lawsuit by the Center for Biological Diversity and the Center for Food Safety, provide an unusually detailed view of a pesticide rulemaking process that typically occurs outside public view. The documents show EPA staff solicited Bayer’s input on restrictions to limit dicamba’s volatility and runoff, ranging from more protective to less protective options. A presentation concluded with a slide titled “Registrant response needed” that posed the question “Which mitigation option to go forward with?”

Bayer chose the least protective option for one regulation and the middle of three levels for another, and asked for an additional option the EPA had not proposed. The agency granted all three of Bayer’s preferences, and they were incorporated into the proposed rule issued a few months later.

In the May 2025 meeting, the EPA gave Bayer two mitigation choices that would allegedly address dicamba’s high volatility — the property that makes the herbicide drift for miles. A more restrictive option would have prevented dicamba applications above 85 degrees Fahrenheit; a less restrictive option would have allowed applications up to 95 degrees if the treated acreage was reduced.

The EPA separately gave Bayer three options for addressing dicamba runoff. After the presentation, an EPA manager wrote in an email that “the next step in the process beyond the [presentation] is getting feedback from the registrants on what mitigation and mitigation implementation option they would like to move forward with.”

Eight days later, a Bayer representative emailed the EPA: “After discussion with EPA and reviewing these options carefully, Bayer would like to proceed as described below …”

Bayer chose the less restrictive volatility option, allowing applications at up to 95 degrees as long as the dicamba-treated area was reduced. Bayer also asked for an option the EPA had not proposed — full-field dicamba treatments at higher temperatures if dicamba was not tank mixed. The EPA granted both requests, along with Bayer’s preferred option for runoff mitigation.

Dicamba is drift prone and kills vegetation and crops for miles around the fields where it is sprayed. The herbicide is linked to liver cancer and Non-Hodgkin lymphoma. Federal courts have twice ordered it off the market because of its drift problems, but the EPA has re-approved it.

Since dicamba’s first approval in 2016, drift from the herbicide has damaged millions of acres of farmland, along with orchards, vegetable farms, home gardens, native plants, trees, and wildlife refuges, according to experts cited by The Guardian. Researchers have characterized dicamba drift damage as the worst of any herbicide in US agricultural history. The current approval provides even fewer protections from drift and damage than past approvals, the lawsuit alleges.

The documents arrive as the EPA has faced criticism for placing former chemical industry leaders in top positions. The top four toxics office positions at the agency are held by former chemical industry leaders, including Kyle Kunkler, a former pesticide industry lobbyist who now serves as deputy assistant administrator and oversees the pesticides program. The plan was also presented to Nancy Beck, a former lobbyist for the American Chemistry Council who now leads the EPA’s office of chemical safety.

Nathan Donley, environmental health science director with the Center for Biological Diversity, said the exchange “crosses a line.”

“The EPA is allowing Bayer to choose its preferred measures to limit dicamba’s damage as if it was ordering up a late-night dinner à la carte from Chili’s,” Donley said. “It becomes troublesome when the EPA allows them to regulate themselves by choosing the mitigations.”

Kelly Ryerson, a “make America healthy again” advocate, was more pointed.

“It is now undeniable that the EPA remains fully captured by a crooked collection of pesticide company players who so enthusiastically ignore the substantial losses of farmers and the federal courts who mandated a halt to dicamba use,” Ryerson said.

“In return for this egregiousness, I would like the EPA to propose a menu of options to Maha for significantly decreasing our exposure to known carcinogens and endocrine disruptors,” Ryerson added.

The EPA defended the process. A spokesperson told The Guardian: “Make no mistake: this is not a compliance failure; it is the regulatory system working exactly as intended.”

“The agency notifies the [pesticide maker] and works with them to identify possible solutions” to risks, the spokesperson wrote. “[Companies] are permitted to submit mitigation ideas that preserve their product’s utility, and EPA also will independently develop its own proposed mitigations. To be explicitly clear: the registrant does not dictate terms.”