Internal documents reveal that the U.S. Environmental Protection Agency (EPA) allowed Bayer, the manufacturer of the weedkiller dicamba, to select regulatory restrictions from a range of options presented by the agency, raising concerns about the integrity of the pesticide approval process.
The documents, released amid ongoing litigation over dicamba’s registration, detail how the EPA solicited Bayer’s preferences on various mitigation measures designed to curb the herbicide’s propensity to drift off-target, which has caused widespread damage to crops, native plants, and wildlife habitats. This approach diverges from the typical regulatory practice where agencies independently determine appropriate safeguards.
Dicamba, a herbicide known for its volatility and tendency to drift, has been linked to damage of millions of acres of farmland and home gardens across the United States since its initial approval in 2016. It has been associated with serious health concerns, including liver cancer and Non-Hodgkin lymphoma. Courts have twice ordered the herbicide off the market due to these drift-related harms, but the EPA has reapproved it with revised regulations each time.
According to records from a May 2025 EPA meeting, the agency provided Bayer with multiple mitigation options to control dicamba’s volatility and runoff. For volatility, Bayer was offered a choice between a more restrictive rule limiting applications to days when temperatures do not exceed 85 degrees Fahrenheit, and a less restrictive alternative permitting use up to 95 degrees Fahrenheit if treated acreage was reduced. For runoff, the EPA presented three options varying in the level of restriction.
Following the presentation, the EPA explicitly requested Bayer's input on which set of measures to advance. Bayer selected the less protective volatility option allowing applications up to 95 degrees with acreage limits, and chose a preferred runoff mitigation alternative proposed by the EPA. Additionally, Bayer secured regulatory approval for an alternative measure not included in the EPA’s initial proposals, allowing full-field dicamba applications at higher temperatures when not tank-mixed.
The finalized regulatory framework reflected Bayer’s selections and was incorporated into the federal rulemaking process shortly thereafter. These developments have drawn criticism from environmental groups engaged in the litigation, who argue that the EPA effectively ceded regulatory control to the pesticide manufacturer. Nathan Donley, environmental health science director at the Center for Biological Diversity, characterized the process as “crossing a line,” warning that it amounted to the EPA allowing the company to shape the measures intended to limit dicamba’s damage.
The EPA has defended its approach, stating that collaboration with registrants is a standard part of the regulatory process and that companies are not permitted to dictate terms. An agency spokesperson emphasized that the regulatory system is functioning as intended and that both the EPA and registrants propose mitigation strategies to address risks.
The controversy adds to concerns about the EPA’s leadership, which includes former pesticide industry lobbyists occupying senior positions in the Office of Chemical Safety and Pollution Prevention. Critics argue that such industry ties may influence regulatory decisions to the detriment of public health and environmental protection.
Advocates for greater oversight called the revelations evidence of undue pesticide industry influence at the agency. Kelly Ryerson, a representative of the advocacy group Make America Healthy Again, stated that the EPA remains “captured by a crooked collection of pesticide company players” ignoring mounting scientific and legal challenges related to dicamba.
As litigation continues, these documents shed new light on the complex and often opaque process by which controversial pesticides are regulated in the United States, raising questions about the balance of power between industry interests and environmental safeguards.