The U.S. Environmental Protection Agency (EPA) has announced the cancellation of all products containing the pesticide dimethyl tetrachloroterephthalate, commonly known as DCPA or Dacthal. This decision was made under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), based on scientific studies indicating thyroid toxicity risks.
Assistant Administrator for the Office of Chemical Safety and Pollution Prevention Michal Freedhoff stated, "With the final cancellation of DCPA, we’re taking a definitive step to protect pregnant women and their unborn babies." The studies suggest that exposure to DCPA could lead to changes in fetal thyroid hormone levels, potentially resulting in low birth weight, impaired brain development, decreased IQ, and impaired motor skills.
DCPA was primarily used for weed control on crops like broccoli and onions. The EPA had previously required AMVAC Chemical Corporation, the sole manufacturer of DCPA, to submit data supporting its registration. However, many submissions were deemed insufficient or not provided at all.
In April 2022, EPA issued a Notice of Intent to Suspend due to incomplete data submission by AMVAC. Although AMVAC later submitted some required studies, EPA maintained concerns over other missing data until November 2023 when sufficient information was finally provided.
Despite voluntary cancellations by AMVAC for turf use in December 2023, significant risks from other uses persisted. In May 2023, an assessment highlighted health risks associated with occupational and residential exposure to DCPA products.
In August 2024, following an emergency suspension—the first such action in nearly four decades—AMVAC indicated its intention to cancel remaining U.S. pesticide registrations and international ones as well. A public comment period followed this announcement before EPA finalized the cancellation order.
The order prohibits distribution or sale of existing stocks of DCPA products. AMVAC has initiated a return program for these products with coordination from EPA to ensure proper disposal according to legal standards.
Further details are available through official notices on Regulations.gov regarding the final cancellation order.
