Chlorpyrifos, a chemical used to prevent insect infestation in crops, has been linked to neurodevelopmental issues, including impaired working memory and lower IQ levels for children who had prenatal exposure to the chemical. Although the chemical has been banned from most household uses, many farmworkers, including pregnant women, still face regular exposure.

The chemical has faced scrutiny for several years and has been the subject of lawsuits. Chlorpyrifos is currently registered and is under registration review, the program that reevaluates all pesticides every 15 years.

In September 2020, the EPA issued two assessments on the chemical:

• Chlorpyrifos: Draft Ecological Risk Assessment for Registration Review, the Chlorpyrifos: Revised Human Health Risk Assessment for Registration Review
• Chlorpyrifos Drinking Water Assessment for Registration Review: Update

These assessments are available in the public docket in EPA-HQ-OPP-2008-0850 at www.regulations.gov.

Regulatory history and EPA actions

In 2000, registrants of chlorpyrifos entered into a voluntary agreement with the EPA to eliminate, phase out, and modify certain uses, including eliminating the chemical from most household uses and discontinuing its use on tomatoes.

Two years later, the EPA provided additional safety measures for those working with the chemical, including:

• Use of buffer zones to protect water quality, fish, and wildlife;
• Reductions in application rates per season on a variety of crops, including citrus and corn; and
• Increase in amount of personal protective equipment to mitigate risk to agricultural workers.

In 2011, the EPA completed a comprehensive preliminary human health risk assessment as part of the registration review process for chlorpyrifos.

The next year, the EPA lowered the aerial pesticide application rates for the chemical and created “no spray” buffer zones around public spaces.

In 2014, the EPA issued a revised human health risk assessment for all uses of the chemical. After receiving public comments on the 2014 published assessment, the EPA issued an updated 2016 human health risk assessment for chlorpyrifos.

In 2017, the EPA denied a petition asking it to reduce all pesticide tolerances for the chemical and cancel its registrations.

“The Agency concluded that despite several years of study, the science addressing neurodevelopmental effects remains unresolved and further evaluation of the science during the remaining time for completion of registration review is warranted,” according to the EPA.

The U.S. 9th Circuit Court of Appeals ordered the EPA to ban chlorpyrifos on August 9, 2018. “The following month, the Department of Justice requested a rehearing before an en banc panel of the court’s judges (an 11-judge panel), which was granted on Feb. 6, 2019, effectively vacating the earlier ruling,” according to the EPA. “After hearing oral argument on March 26, on April 19, 2019, the court ordered EPA to issue a final decision with respect to the petition objections within 90 days and did not otherwise address the issues raised in the case.”

Opponents of the chemical question why it is regulated by the EPA and don’t believe the EPA has the proper perspective to protect agriculture workers, said Iris Figueroa, an attorney with Farmworker Justice, which is currently suing to ban chlorpyrifos, according to The Hill. For other industry sectors, the Occupational Safety and Health Administration regulates chemical exposure for workers.

“The Environmental Protection Agency is tasked with protecting the environment but when it comes to pesticides that affect the environment, farm workers are affected as well, but the focus often is on the registration of the products and there’s a lot of industry voice in that process and there’s not, we feel, an equal voice for the workers,” Figueroa said.

The Agency recently said that “despite several years of study, the science addressing neurodevelopmental effects remains unresolved.”

Advocates believe this signals the EPA does not plan to ban use of the chemical.

Opponents of the chemical hope to find relief in court.

“Patti Goldman, an attorney with Earthjustice, said the court could rule one of three ways: that the EPA doesn’t have to do anything, that it would give the agency a certain amount of time to find the substance safe if it wants to proceed without a ban, or it could require a ban,” according to The Hill.

For additional information, see Pesticide Registration Review: Draft Human Health and/or Ecological Risk Assessments for Chlorpyrifos.