4 new pesticides ignite debate over PFAS definition

The US Environmental Protection Agency is doubling down on efforts to decrease a backlog of new pesticide active ingredients waiting for EPA approval to enter the marketplace. Since April, the agency has proposed registering four of them—cyclobutrifluram, diflufenican, isocycloseram, and trifludimoxazin.All four pesticides contain a fully fluorinated methyl or methylene group, raising concerns that they will persist in soil and water for many years. Environmental groups argue that the chemicals are per- and polyfluoroalkyl substances (PFAS) under the definition recommended by the Organisation for Economic Co-operation and Development (OECD) in 2021. PFAS are notoriously difficult to remove from the environment, and some of them are toxic at extremely low levels. The proposed active ingredients have half-lives of over 3 years, which means that half of what is sprayed today will still be contaminating soil and water in 3 years, at the time of the next US presidential election, Nathan Donley, environmental health science director at the Center for Biological Diversity, said during a meeting of the EPA’s Pesticide Program Dialogue Committee (PPDC) on June 17. Donley is a member of the PPDC, representing the environmental group’s perspective. “It’s like PFAS pollution on steroids these past few months,” he said, referring to the EPA’s plan to approve the four pesticides. The EPA’s pesticides office “appears to have absolutely no plan to account for the fact that actives are getting more persistent and fluorinated breakdown products are essentially going to be around forever.” The proposed pesticide active ingredients can degrade into trifluoroacetic acid, which