The U.S. Environmental Protection Agency announced the emergency suspension of all registrations of the pesticide dimethyl tetrachloroterephthalate under the Federal Insecticide, Fungicide and Rodenticide Act. The action, the first of its kind in nearly 40 years, is part of the Biden-Harris Administration's effort to assess and address risks posed by the pesticide.
According to the U.S. Environmental Protection Agency (EPA), exposure to dimethyl tetrachloroterephthalate (DCPA or Dacthal) during pregnancy can lead to changes in fetal thyroid hormone levels, which are linked to low birth weight, impaired brain development, decreased IQ, and impaired motor skills later in life, some of which may be irreversible. Assistant Administrator for the Office of Chemical Safety and Pollution Prevention Michal Freedhoff stated, "DCPA is so dangerous that it needs to be removed from the market immediately."
DCPA, primarily used on crops such as broccoli, brussels sprouts, cabbage, and onions, is currently undergoing registration review. In 2013, the EPA issued a Data Call-In (DCI) to AMVAC Chemical Corporation, the sole manufacturer of DCPA, requiring the submission of more than 20 studies to support the existing registrations. However, several studies submitted by AMVAC from 2013-2021 were considered insufficient, and some, including a comprehensive study on the effects of DCPA on thyroid development and function, were not submitted at all.
In May 2023, the EPA released its assessment on the risks of occupational and residential exposure to DCPA, finding health risks associated with its use and application, even when personal protective equipment and engineering controls were used. The most serious risks are to unborn babies, with some potentially being subjected to exposures 4 to 20 times greater than what the EPA has estimated as safe.
The EPA also expressed concern about risks to unborn babies of pregnant individuals entering or working in areas where DCPA has been applied, as well as those living near areas where DCPA is used due to spray drift. Current product labels specify a 12-hour restricted entry interval after application, but evidence indicates that for many crops and tasks, DCPA levels remain unsafe for 25 days or more.
Despite AMVAC's proposed changes to DCPA registrations, including the cancellation of products registered for use on turf, the EPA determined that these changes do not adequately address the serious health risks for people who work with and around DCPA in agricultural settings.
The Emergency Order is effective immediately, as the EPA determined that the continued sale and use of DCPA products during the normal cancellation process poses an imminent hazard to unborn babies. The agency intends to issue a notice of intent to cancel DCPA products within the next 90 days.
