On August 6, the U.S. Environmental Protection Agency announced the temporary suspension of all registrations of the pesticide dimethyltetrachloroterephthalate (DCPA or Dacthal) under the Federal Insecticide, Fungicide and Rodenticide Act.
This is the first time in nearly 40 years that EPA has taken such an emergency action, after several years of efforts by the Biden administration to require the production of long-overdue data and then to assess and address the risk posed by this pesticide.
According to the EPA, unborn babies whose pregnant mothers are exposed to DCPA – sometimes without even knowing that such exposure has occurred – may experience changes in fetal thyroid hormone levels. These changes are generally associated with low birth weight, impaired brain development, reduced IQ and impaired motor skills later in life, some of which may be irreversible.
“DCPA is so dangerous that it must be removed from the market immediately,” said Michal Freedhoff, deputy director of the Office of Chemical Safety and Pollution Prevention. “It is EPA’s job to protect people from exposure to dangerous chemicals. If this happens, pregnant women who may never have known they were exposed to these chemicals could give birth to babies who suffer lifelong, irreversible health problems.”
Congressman Raúl Grijalva (AZ-07) said, “Farmworkers face stressful conditions in the fields and are often exposed to harmful pesticides as they work to feed our country. I applaud EPA’s emergency action that prioritizes the health and safety of farmworkers, especially pregnant women, by eliminating these harmful chemicals from our agricultural systems.”
Mily Treviño Sauceda, executive director of the Alianza Nacional de Campesinas, said: “The Alianza is pleased with this historic decision by the EPA. As an organization led by farmworkers, we know exactly the damage that pesticides, including dimethyltetrachloroterephthalate (DCPA or Dacthal), can do to our bodies and our communities. This emergency decision is a great first step that we hope will follow a series of other steps based on listening to farmworkers, protecting our reproductive health and protecting our families.”
DCPA is a pesticide approved for weed control in 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 registered pesticides to be re-evaluated every 15 years to ensure they do not cause unreasonable negative effects on human health or the environment.
The EPA consulted with the U.S. Department of Agriculture to understand how farmers use DCPA and what alternatives exist. In 2013, the agency asked AMVAC Chemical Corp., the sole DCPA manufacturer based in Newport Beach, to submit more than 20 studies to support existing DCPA approvals.
The required data included a comprehensive study of the effects of DCPA on thyroid development and function in adults and in developing children before and after birth, which had to be available by January 2016.
Several of the studies submitted by AMVAC between 2013 and 2021 were deemed insufficient to address the concerns, 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 engineered product DCPA (used to manufacture end-use products) because AMVAC had failed to submit the full set of required data, including the thyroid study, for nearly 10 years.
While AMVAC submitted the required thyroid study in August 2022, EPA suspended registration because AMVAC continued to fail to submit other pending data following an administrative hearing on August 22, 2023. In November 2023, the suspension of data submission was lifted after AMVAC submitted sufficient data. Most DCPA applications on turfgrass were voluntarily discontinued by AMVAC in December 2023, but unacceptable risks from other uses remained.
In May 2023, the EPA released its assessment of the risks of occupational and home exposure to products containing DCPA after analyzing the thyroid study submitted by AMVAC. The assessment found that there are health risks associated with the use and application of DCPA, even when personal protective equipment and engineering controls are used. The most serious risks are to the unborn children of pregnant individuals.
The U.S. Environmental Protection Agency (EPA) estimates that pregnant women handling DCPA products could be exposed to levels four to twenty times higher than the level considered safe for unborn babies by the EPA.
Also of concern are the risks to unborn babies of pregnant women who enter or work in areas where DCPA has already been applied (particularly workers who perform post-application tasks such as transplanting, weeding and harvesting).
Current product labels indicate that entry to treated fields must be prohibited for 12 hours after treatment. However, there is evidence that for many crops and applications, DCPA levels in a treated field remain at unsafe levels for 25 days or more.
Pesticide drift (the spreading of pesticides through the air at the time of application or shortly thereafter to a location other than the intended location) could also pose a risk to the unborn babies of pregnant women living near areas where DCPA is used.
Since the release of the 2023 EPA assessment, AMVAC has proposed several changes to the DCPA registrations, including delisting DCPA products registered for use on turf surfaces. These delistings virtually eliminate DCPA exposure during recreational activities on and around turf surfaces.
But according to EPA’s analysis, AMVAC’s proposed changes to the agricultural use of DCPA did not adequately address the serious health risks to people who work with or around DCPA.
In April 2024, the EPA issued a public alert highlighting the significant health risks to unborn babies of pregnant women exposed to DCPA and its intention to take action as soon as possible to correct the serious, and in some cases permanent and irreversible, health risks associated with the pesticide.
In a letter to AMVAC dated March 27, 2024, EPA reiterated the risks identified by the agency and noted that the agency will pursue regulatory options as soon as possible, which could include repealing the pesticide or requesting an emergency suspension.
If serious risks are identified, EPA may take action under FIFRA to suspend or delist a pesticide. Such actions are resource and time intensive, in part due to FIFRA’s procedural requirements. A delisting process can take at least several months (if not contested by the registrant) or potentially several years (if contested by the registrant, triggering an administrative hearing and subsequent appeal of a delisting order). FIFRA also allows EPA to request a suspension of a pesticide product while a delisting process is underway if the Administrator determines it is necessary to address an imminent hazard.
EPA Administrator Michael Regan has determined that due to the serious and immediate harm caused by DCPA, an emergency exists that necessitates this immediate suspension order. EPA intends to issue a notice of intent to discontinue DCPA products within the next 90 days.
The emergency order takes effect immediately. EPA has determined that the continued sale and use of DCPA products during the time it would take to complete the normal withdrawal process poses an imminent danger to unborn babies. Although AMVAC has attempted to address these concerns, EPA has determined that there are no practical remedies that would allow the continued use of DCPA.
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For more information, see DCPA Registration Review Protocol EPA-HQ-OPP-2011-0374
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