Center for Biological Diversity

For Immediate Release, August 18, 2022


Nathan Donley, (971) 717-6406,

Cancer-Linked Pesticide 1,3-D Moves Closer to Reapproval

EPA Proposal Relies on Pesticide Makers’ Studies, Ignores Independent Science

WASHINGTON— The Environmental Protection Agency proposed today to reapprove the cancer-linked fumigant 1,3-Dichloropropene with a less-protective classification that will increase exposure levels considered to be safe by 90-fold.

The pesticide known as 1,3-D is linked to cancer and respiratory problems in farmworkers. It is the nation’s fourth most widely used pesticide, with an estimated 40 million pounds used each year on crops like potatoes, cotton, strawberries and peppers.

The EPA’s decision to assign the pesticide a less-restrictive cancer designation relied largely on modelling done by the maker of 1,3-D, Dow AgroSciences. Those models and an incomplete search strategy for new research ended up discounting numerous peer-reviewed studies by independent scientists and governmental agencies showing that the pesticide causes cancer.

As a result the EPA indicated it will downgrade its cancer classification of the pesticide from “Likely to be Carcinogenic to Humans” to “Suggestive Evidence of Carcinogenic Potential.” The decision negates the need for a separate, more detailed assessment of how the pesticide can cause cancer.

“The EPA’s proposal to dramatically increase farmworkers’ allowable exposure to this carcinogen flies in the face of the Biden administration’s commitments to end cancer and promote environmental justice,” said Nathan Donley, environmental health science director at the Center for Biological Diversity. “Just because the pesticide company says its product is safe doesn’t mean it’s safe. It’s the height of irresponsibility to rely on the pesticide industry’s assessments of its own product to make a change that risks causing serious health problems for thousands of people.”

This change in cancer classification means that the amount of 1,3-D that the EPA considers safe will be 90 times higher than the concentration that it previously found to cause cancer. The resulting risks will be greatest to farmworkers, who already suffer many health problems such as cancers and reproductive harms from exposure to pesticides.

The EPA’s finding runs counter to many other U.S. and international agencies that have found that 1,3-D is linked to cancer. These agencies include the U.S. National Toxicology Program, the U.S. National Institute of Occupational Safety and Health, the EPA’s Integrated Risk Information System program and Office of Water, the Centers for Disease Control and Prevention’s Agency for Toxic Substances and Disease Registry, the California Environmental Protection Agency and the World Health Organization’s International Agency for Research on Cancer.

The EPA’s decision to downgrade 1,3-D’s cancer classification was also the subject of a strong rebuke by its watchdog office, the Office of Inspector General. The OIG found that the EPA did not have the proper guidance in place to incorporate the highly speculative modelling used by the pesticide registrant and that the agency was not transparent with the public during its approval process. Further, the OIG found that the EPA failed to conduct a search for all independent studies on 1,3-D causing cancer, resulting in many independent studies not being reviewed.

The OIG also uncovered that the EPA had its work peer-reviewed by people who were paid by the pesticide company instead of by an independent group of scientists. The EPA replied that: “the Agency believes the external peer review sponsored by the registrant meets the intent of the recommendation to conduct an external peer review on the 1,3-D cancer assessment.”

The initial proposal to put a less-protective standard in place for the pesticide was initiated during the final days of the Trump administration in December of 2020. Today’s amended proposal maintains that decision.

“There’s absolutely no reason that a political move made in the waning days of the Trump EPA to enrich one of his major campaign donors at the expense of human lives should remain in place,” said Donley. “We’re extremely disappointed in how the EPA has handled this. I hope the agency can get back in line with the rest of the federal government and agencies around the world and take commonsense action to protect people from this dangerous chemical poison.”

The Center for Biological Diversity is a national, nonprofit conservation organization with more than 1.7 million members and online activists dedicated to the protection of endangered species and wild places.

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