For Immediate Release, September 9, 2019


Nathan Donley, (971) 717-6406,

Trump’s EPA Proposes to Keep Ignoring Harmful, Increased Toxicities of Pesticide Combinations

WASHINGTON— The U.S. Environmental Protection Agency issued proposed guidelines today to allow the agency to continue ignoring the heightened toxic effects on plants, bees and other wildlife when pesticides are mixed.

“It’s appalling that the pesticide office at EPA is willfully ignoring the risk these toxic pesticide combinations pose to wildlife,” said Nathan Donley, a senior scientist at the Center for Biological Diversity who authored a 2016 report on the increased toxicity of pesticide concoctions.

The Center’s 2016 report found that pesticide companies seeking patents on new products routinely provide detailed evidence to the U.S. Patent and Trademark Office of the increased toxicities caused by the new combinations of pesticides. The report revealed that more than two-thirds of new pesticides registered in the previous six years by four major pesticide companies had patents demonstrating their new products' enhanced toxicity — effects the EPA failed to consider.

The EPA’s Inspector General subsequently called on the agency to assess the enhanced toxicities of pesticide mixtures and the possibility of requiring more information by pesticide companies. The EPA has since begun analyzing information in patent applications on an extremely limited scale as part of its risk assessment process. But the agency has largely discounted that evidence.

Of the 24 pesticide ingredients that have undergone a patent review since the EPA was alerted to the issue of relevant toxicity data in patents, no further protections were required for any of them based on enhanced mixture toxicity.

While the EPA’s new guidance proposes to require pesticide companies to submit patent data on synergistic effects, the requirement ignores information relevant to accurately assessing risk.

The proposal:

  • Only seeks information from approved U.S. patents, ignoring unapproved or pending patent applications, patents in other countries and other relevant information on synergy that is not included in patent applications;
  • Only seeks information on synergy between active pesticide ingredients, ignoring synergy that can happen between pesticides and other ingredients in formulated products;
  • Ignores data on enhanced toxicity to certain organisms like fungi, which play an essential role in soil health;
  • Only requires a patent data analysis for new pesticide ingredients and not during routine registration reviews of previously approved pesticides, essentially exempting pesticides that are already approved from further review;
  • Directs the EPA to adopt the process it currently uses to ignore toxicity data from academic research in peer-reviewed literature and base its decisions solely on specific industry studies that meet an arbitrary oversight standard.

“For the EPA to knowingly turn a blind eye to the well-documented harmful effects of pesticide mixtures in wide use across the U.S. is a travesty,” said Donley. “The EPA’s insistence on pretending that pesticides are encountered in isolation is putting people and the environment in harm’s way.”


In late 2015, in preparing to defend itself against litigation on the registration of a pesticide product called Enlist Duo, the EPA discovered a new source of information on the product: the U.S. Patent and Trademark Office Database. The database contained a patent application indicating the two ingredients in this product, glyphosate and 2,4-D, resulted in synergistic toxicity to plants. This discovery ultimately led the agency to ask the 9th Circuit Court of Appeals to vacate its approval of Enlist Duo because it had not properly considered the potential adverse effects of this synergy on nontarget plants. It also highlighted a previously unknown source of much-needed mixture toxicity data: patent applications.

When a chemical company develops a new product, in addition to seeking approval for that product from the EPA, it will often apply for patent protection on the mixture. Such an application is typically accompanied by data that demonstrate synergistic toxicity to the organisms that are going to be targeted by the chemicals.

Subsequent findings in the Center for Biological Diversity's landmark analysis, Toxic Concoctions: How the EPA Ignores the Dangers of Pesticide Cocktails, found that more than two-thirds of new pesticides registered from 2010 to 2016 had patents demonstrating their new products' synergistic effects with other pesticides — effects the EPA failed to consider. The analysis also found that the majority of new pesticide patent applications identified synergy between some of the most frequently used pesticides in the United States, including glyphosate, atrazine, 2,4-D, dicamba and multiple neonicotinoids.

The Center then petitioned the EPA to require pesticide companies to provide data on the synergistic effects of pesticide products when seeking approval for those products. The petition remains unanswered.

The Center for Biological Diversity is a national, nonprofit conservation organization with more than 1.6 million members and online activists dedicated to the protection of endangered species and wild places.