The U.S. Environmental Protection Agency (EPA) has asked the U.S. Court of Appeals for the Ninth Circuit for a chance to withdraw the agency’s own decision to approve difenoconazole, a fungicide used to mitigate mold and mildew in potatoes, grapes, soybeans, tomatoes, almonds, and other crops. EPA made its request after considering a lawsuit filed by the Center for Food Safety (CFS), which petitioned the court to reverse EPA’s registration of the fungicide. Syngenta Crop Protection LLC, which holds EPA registrations for difenoconazole, was also listed on the petition as a respondent-intervenor.

CFS asserted that EPA “blatantly and intentionally” ignored the neurological harms that difenoconazole poses to humans, as well as its damaging effects to wildlife, when the agency renewed its approval of the fungicide. CFS stated that EPA violated the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and the Endangered Species Act (ESA) in its failure to collect relevant studies on the risks that difenoconazole poses to public health and animal life, calling the agency’s approval of the fungicide “unlawful.”

In its argument, CFS cited EPA’s acknowledgement of the damaging effects that difenoconazole can have on wildlife, and that the agency did not confer with the U.S. Fish and Wildlife Service or the National Marine Fisheries Service about those risks. According to CFS, EPA’s own analysis found that exposure to the fungicide exceeds the level of concern for birds, aquatic invertebrates, and freshwater fish, putting several endangered species at risk. CFS also mentioned the Ninth Circuit Court’s June 2022 decision regarding the pesticide glyphosate in its argument, stating that the prior ruling demonstrates that EPA cannot disregard its ESA duties, and that the present case regarding difenoconazole is no different than the glyphosate registration.

Furthermore, CFS stated that EPA has been concerned with the toxicity of difenoconazole and other triazole fungicides for over two decades. Specifically, when the fungicides break down, they form chemical compounds that may be carcinogenic to humans, and could also impair infants’ brain and vital organ development. CFS asserted that, in 2000, the agency placed a moratorium on further approvals of triazole until the manufacturers of such products could submit studies demonstrating the relative safety of the fungicides. Although triazole manufacturers failed to submit qualifying studies, EPA dissolved the moratorium in 2006.

As a result of CFS’ lawsuit, EPA submitted a request for voluntary remand of its decision, stating that the agency wishes to reconsider the need for additional studies related to metabolites of difenoconazole. While the agency denied the existence of a formal call for data issued in 2000 for triazole and its conjugates, EPA did admit that, in 2002, the agency issued a letter to the U.S. Triazole Task Force expressing the need for additional information regarding the potential risks associated with exposure to triazole, which is a metabolite of difenoconazole. EPA also acknowledged that, in completing its 2006 risk assessment of triazole, the agency noted uncertainties related to data gaps in the toxicological database for triazole metabolites. Since EPA has not received all of the studies referenced in its 2006 risk assessment, the agency agrees that its approval of difenoconazole was not fully informed and necessitates a more thorough investigation.

EPA anticipates withdrawing its difenoconazole decision within 30 days of the Court granting the agency’s motion for remand. EPA intends to further investigate the issue of outstanding data needs related to the toxicology of triazole metabolites and its conjugates of concern, and will evaluate whether any additional data is needed to support future registration review decisions for difenoconazole products.