The U.S. Environmental Protection Agency (EPA) in August announced a rare emergency suspension of “all registrations of 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,” the agency stated.

“Also known as DCPA, dimethyl tetrachloroterephthalate and chlorthal-dimethyl, the herbicide was banned in the European Union in 2009, and the EPA has long known of its potential harm to people,” the Environmental Working Group (EWG) stated.

“The EPA’s decision to finally suspend DCPA is welcome news, but it’s long overdue,” said EWG Senior Toxicologist Alexis Temkin, Ph.D.

“For years, EWG and other public health advocates have warned about the serious risks the weedkiller poses to farmworkers, pregnant people and other vulnerable populations,” Temkin added.

Per EWG:

In 1995 – nearly 30 years ago – the agency classified DCPA as a “possible carcinogen.”. That decision was based on a study conducted by Dacthal’s manufacturer in 1993, which showed it caused thyroid tumors in animals, suggesting similar potential threats to people.

In 2013, the EPA required AMVAC, the sole DCPA manufacturer in the U.S., to submit an additional study showing the chemical’s effects on the fetal thyroid among other information.

AMVAC’s research, finally submitted to the EPA in 2022, showed even low doses of DCPA exposure can harm the developing fetus.

During the nearly 10 years before it finally complied with the EPA’s requirement, the company continued producing and selling Dacthal.

And AMVAC didn’t submit other data requested. So in August 2023, the agency suspended use of the pesticide, a de facto temporary ban.

Yet three months later the EPA lifted that suspension, once again allowing Dachtal’s use – until today.

The EPA’s emergency order immediately halts all uses of the herbicide.

“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,” the EPA wrote.

“DCPA is so dangerous that it needs to be removed from the market immediately,” said Assistant Administrator for the Office of Chemical Safety and Pollution Prevention Michal Freedhoff.

“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,” Freedhoff continued.

From the EPA:

DCPA is a pesticide registered to control weeds in both agricultural and non-agricultural settings, but is primarily used on crops such as broccoli, Brussels sprouts, cabbage and onions. DCPA is currently undergoing registration review, a process that requires reevaluating registered pesticides every 15 years to ensure they cause no unreasonable adverse effects on human health or the environment.

In deciding whether to issue today’s Emergency Order, EPA consulted with the U.S. Department of Agriculture to understand how growers use DCPA and alternatives to this pesticide. In 2013, the agency 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, that was due by January 2016. Several of the studies that AMVAC submitted from 2013-2021 were considered insufficient to address the DCI, while the thyroid study and other studies were not submitted at all.

In April 2022, EPA issued a very 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. While AMVAC submitted the required thyroid study in August 2022, EPA suspended the registration based solely on AMVAC’s continued failure to submit other outstanding data on Aug. 22, 2023, following an administrative hearing. In November 2023, the data submission suspension was lifted after AMVAC submitted sufficient data. Most DCPA use on turf was voluntarily canceled by AMVAC in December 2023, but unacceptable risks from other uses remained.

In May 2023, 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 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. 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.

 

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