Trump EPA ignored own guidelines by dismissing cancer risks for widely used pesticide, Inspector General finds

WASHINGTON – During the Trump administration, Environmental Protection Agency officials downgraded the agency’s long-held position that a widely used pesticide could give people cancer, the EPA’s internal watchdog has found. That decision broke the agency’s cancer risk assessment rules.

In a scathing report released last week by the EPA’s Office of Inspector General, or OIG, investigators found multiple flaws in the agency’s 2019 cancer risk evaluation for the pesticide 1,3-Dichloropropene, or 1,3-D. The fumigant is widely used by farmers to combat nematode worms that burrow in soil and can threaten various crops.

In 1985, the Reagan administration declared 1,3-D as “likely to be carcinogenic to humans” exposed to the substance. The Trump EPA downgraded the risk to “suggestive evidence of carcinogenic potential” but without following its standard operating procedures and other guidelines for cancer risk reviews, the OIG report said.

“This change in cancer classification by the EPA has big impacts when it comes to determining how much of the pesticide is considered safe,” said Environmental Working Group toxicologist Alexis Temkin, Ph.D.

The downgraded classification means non-organic farming operations could use far more 1,3-D on fields, putting farmworkers and nearby communities at even greater risk.

“The EPA’s decision to ignore the evidence that 1,3-D may cause cancer is a gift for chemical agriculture operations, but it will put farmworkers, their families and all those who live, work and go to school near these farms at even greater risk of pesticide exposure than they already are,” said Temkin.

The OIG investigation was first reported by E&E News and also covered by The New Lede, EWG’s recently launched independent journalism initiative.

“The EPA did not adhere to standard operating procedures and requirements for the 1,3-Dichloropropene, or 1,3-D, pesticide cancer-assessment process, which undermines public confidence in and the transparency of the Agency’s scientific approaches to prevent unreasonable impacts on human health,” said the OIG.

The OIG suggested nine steps the agency could take “to improve the transparency of the 1,3-D cancer-assessment process and restore the scientific credibility of the Agency’s 1,3-D cancer classification.”

Besides posing a risk of cancer, 1,3-D can also harm the respiratory system and drift easily from farms into nearby neighborhoods. A groundbreaking analysis by EWG published in February that mapped pesticides, including 1,3-D, sprayed in Ventura County, Calif., found that more than 32 million pounds of crop chemicals had been sprayed in that county alone between 2015 and 2020.

Almost 70 percent of all homes in Ventura are within 2.5 miles of an agricultural operation where pesticides like 1,3-D are regularly sprayed, with more than one in four homes located within a half-mile of such farm fields. More than 30 elementary schools in the county are within a quarter-mile of farm fields where 1,3-D is often used.


The Environmental Working Group is a nonprofit, non-partisan organization that empowers people to live healthier lives in a healthier environment. Through research, advocacy and unique education tools, EWG drives consumer choice and civic action

Full disclosure: The New Lede is a journalism initiative of EWG and is a distinct service that operates independently of the organization’s advocacy and communications units. EWG has no influence on editorial decision-making at The New Lede.

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