EPA Warns Farmworkers about Risks of Dacthal

On April 1, EPA announced its next steps to protect people from the herbicide dimethyl tetrachloroterephthalate or DCPA, or Dacthal. 

EPA is warning people of the significant health risks to pregnant individuals and their developing babies exposed to DCPA and will be pursuing action to address the serious, permanent, and irreversible health risks associated with the pesticide as quickly as possible. EPA has also issued a letter to AMVAC, the sole manufacturer of DCPA, restating the risks the agency found and stating that due to the serious risks posed by DCPA, the agency is pursuing further action to protect workers and others who could be exposed. EPA is taking this rare step of warning farmworkers about these concerns while it works on actions to protect workers because of the significant risks the agency has identified.

DCPA is an herbicide 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 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 May 2023, EPA released its assessment on the risks of occupational and residential exposure to products containing DCPA, after the agency reviewed data that it compelled AMVAC to submit, which had been overdue for almost 10 years. The assessment found concerning evidence of health risks associated with DCPA use and application, even when personal protective equipment and engineering controls are used. The most serious risks extend to the developing babies of pregnant individuals. EPA estimates that some pregnant individuals handling DCPA products could be subjected to exposures from four to 20 times greater than what current DCPA product label use instructions indicate is considered safe. EPA is concerned that pregnant women exposed to DCPA 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.

Also of concern are risks to developing 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 the previously treated fields remained at unsafe levels for 25 days or more. EPA also identified potential risks for individuals using golf courses and athletic fields after DCPA was applied. Spray drift from pesticide application could also put developing babies at risk for pregnant individuals living near areas where DCPA is used.

Supporting documents are available in the DCPA registration review docket EPA-HQ-OPP-2011-0374 on the Regulations.gov.

Read EPA’s Response to AMVAC’s Mitigation Proposal.