The EPA recently announced it issued emergency orders to suspend all registrations for the pesticide dimethyl tetrachloroterephthalate (DCPA or Dacthal) under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA).

“This is the first time in almost 40 years EPA has taken this type of emergency action, following several years of unprecedented efforts by the Biden-Harris Administration to require the submission of long-overdue data and then assess and address the risk this pesticide poses,” states an Agency news release. “EPA has taken this action because unborn babies whose pregnant mothers are exposed to DCPA, sometimes without even knowing the exposure has occurred, could experience changes to fetal thyroid hormone levels, and these changes are generally linked to low birth weight, impaired brain development, decreased IQ, and impaired motor skills later in life, some of which may be irreversible.

“DCPA is so dangerous that it needs to be removed from the market immediately,” said Michal Freedhoff, assistant administrator for the Office of Chemical Safety and Pollution Prevention, in the Agency release. “It’s EPA’s job to protect people from exposure to dangerous chemicals. In this case, pregnant women who may never even know they were exposed could give birth to babies that experience irreversible lifelong health problems. That’s why for the first time in almost 40 years, EPA is using its emergency suspension authority to stop the use of a pesticide.”

DCPA background

DCPA is a registered pesticide that’s used for weed control. According to the EPA, it’s primarily used on crops like broccoli, Brussels sprouts, cabbage, and onions.

It’s currently undergoing registration review, a process that requires a reevaluation of registered pesticides every 15 years to ensure they have no unreasonable adverse effects on human health or the environment.

EPA DCPA timeline

• 2013: The EPA issued a Data Call-In (DCI) to AMVAC Chemical Corporation, the sole manufacturer of DCPA, requiring it to submit more than 20 studies to support the existing registrations of DCPA.

The required data included a comprehensive study of the effects of DCPA on thyroid development and function in adults and in developing young before and after birth, which was due by January 2016.

• Several studies AMVAC submitted from 2013 to 2021 were considered insufficient to address the DCI, while the thyroid study and other studies were not submitted at all.
• April 2022: The EPA issued a rarely used Notice of Intent to Suspend the DCPA technical-grade product (used to manufacture end-use products) based on AMVAC’s failure to submit the complete set of required data for almost 10 years, including the thyroid study.
• August 22, 2023: The EPA suspended the DCPA’s registration following an administrative hearing. Although AMVAC submitted the required thyroid study in August 2022, the Agency suspended the registration because the company failed to submit other outstanding data.
• November 2023: The data submission suspension was lifted after AMVAC submitted sufficient data.
• December 2023: Most DCPA use on turf was voluntarily canceled by AMVAC, but unacceptable risks from other uses remained.
• May 2023: The EPA released its assessment on the risks of occupational and residential exposure to products containing DCPA following its analysis of the thyroid study submitted by AMVAC.

The EPA’s assessment found health risks associated with DCPA use and application, even when personal protective equipment and engineering controls are used.

“The most serious risks are to the unborn babies of pregnant individuals,” the EPA news release adds. “EPA estimates that some pregnant individuals handling DCPA products could be subjected to exposures four to 20 times greater than what EPA has estimated is safe for unborn babies.

“Also of concern are risks to unborn babies of pregnant individuals entering or working in areas where DCPA has already been applied (especially post-application workers involved in tasks such as transplanting, weeding and harvesting). Current product labels specify that entry into treated fields must be restricted for 12 hours after application. However, the evidence indicates that for many crops and tasks, levels of DCPA in a treated field remain at unsafe levels for 25 days or more. Spray drift (the movement of pesticide through the air at the time of application or soon after, to any site other than the area intended) from pesticide application could also put at risk the unborn babies of pregnant individuals living near areas where DCPA is used.”

• April 2024: The EPA issued a public warning regarding the significant health risks to unborn babies of pregnant individuals exposed to DCPA and its intent to pursue action to address the serious and, in some instances, permanent and irreversible health risks associated with the pesticide as quickly as possible.
• March 27, 2024: The EPA sent AMVAC a letter restating the risks the Agency found and noting it would be pursuing rapid regulatory options, which could include canceling the pesticide or seeking an emergency suspension.

“Since the release of EPA’s 2023 assessment, AMVAC has proposed several changes to the DCPA registrations, including the cancellation of DCPA products registered for use on turf,” the EPA release continues. “Those cancellations practically eliminate exposures to DCPA from recreational activities on and around turf. But according to EPA’s analysis, AMVAC’s proposed changes to agricultural uses of DCPA do not adequately address the serious health risks for people who work with and around DCPA.”

In deciding whether to issue the emergency order, the EPA consulted with the U.S. Department of Agriculture to understand how growers use DCPA and alternatives to this pesticide.

“When serious risks are identified, EPA can take action under FIFRA to suspend or cancel a pesticide,” according to Vicksburg Daily News. “Taking such action is resource and time intensive, partly due to the procedural requirements of FIFRA. A cancellation proceeding may take at least several months (if uncontested by the registrant) or potentially several years (if contested by the registrant, thus triggering an administrative hearing and any subsequent appeal of a cancellation order). FIFRA also allows EPA to seek a suspension of a pesticide product while cancellation proceedings are ongoing if the Administrator determines it is necessary to prevent an imminent hazard.”