DCPA (Dacthal) technical herbicide product suspended by the U.S. EPA

Effective August 22, 2023, the U.S. Environmental Protection Agency suspended the technical-grade product containing the pesticide dimethyl tetrachloroterephthalate (DCPA), marketed under the trade name Dacthal, for failure of the registrant to submit required data to support its continued registration. Technical-grade products are high-concentration forms of pesticides that are formulated into end-use pesticide products. This suspension prohibits the sale, distribution, and use of this DCPA technical product, including use to formulate new end-use product. Existing end-use products containing DCPA, including those that are being distributed, sold, or already in the hands of pesticide users, are not subject to this suspension action and can still be used according to the label.

DCPA is an herbicide applied to control grasses and certain broadleaf weeds in both agricultural and non-agricultural settings. Agricultural use sites include cole crops (e.g., broccoli, kale, cabbage), cucurbits, tomatoes, onions, and herbs. Non-agricultural use sites include non-residential turf and ornamentals.

As required by FIFRA, EPA periodically re-evaluates pesticides through registration review to ensure that risk assessments and pesticide decisions reflect the best available science. Part of the registration review process is to identify risks of concern and to implement actions that can mitigate these risks. To ensure the Agency has data to assess risks based on current risk assessment policies, EPA can issue a data call-in (DCI) that requires registrants to fulfill specified data requirements by certain dates. EPA issued a DCI to AMVAC in January 2013 requiring it to submit numerous studies to support the existing registrations of DCPA. The DCI required that all studies be submitted to the Agency within three years.

The data required by EPA included a comprehensive study of the effects of DCPA on thyroid development and function in adults and before birth. In the absence of these data, EPA reviewed preliminary data submitted by AMVAC, which suggest that DCPA can affect thyroid function at lower doses than previously known, and that it may affect a fetus at lower doses than those that adversely affect adults. Without complete data on the thyroid toxicity of DCPA, the Agency was unable to complete the scientifically robust and defensible human health risk assessment needed to evaluate whether DCPA products continue to meet the standard for registration under FIFRA.

On April 28, 2022, EPA issued a notice of intent to suspend (NOITS) this DCPA technical product because AMVAC, the sole registrant, had not provided the full complement of data the Agency required it to submit by no later than January 2016. At the time the Agency issued the NOITS, the data were six years overdue. AMVAC requested a hearing on the NOITS. Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) Section 3(c), registrants are required to submit data to support the continued registration of their products. The Administrative Law Judge (ALJ) who adjudicated this case ruled in favor of EPA’s authority to require registrant to submit data according to deadlines provided in DCIs, and to enforce compliance with DCIs through administrative suspension proceedings under FIFRA Section 3(c)(2)(B), so EPA can make informed and health-protective decisions as part of our pesticide evaluation process.

In a May 16, 2023 decision, the ALJ ruled in favor of EPA and determined that the suspension would become effective when the decision was made final. On August 16, 2023, the Agency entered into a settlement agreement with AMVAC to expedite submission and screening of the outstanding data. Through an August 22, 2023, order from the Environmental Appeals Board, the ALJ’s decision became final and the suspension of the DCPA technical product went into effect.

It is unlawful for AMVAC to distribute, sell, or use its technical-grade DCPA pesticide product until EPA lifts the suspension. This restriction applies to use of the DCPA technical product to formulate end-use products. Stocks of DCPA end-use pesticide products that were already formulated prior to August 22, 2023, may continue to be distributed, sold, and used according to the label. EPA will lift the suspension after EPA confirms AMVAC has submitted the required data as specified in the settlement agreement.

Supporting documents are available in the DCPA registration review docket EPA-HQ-OPP-2011-0374 at www.regulations.gov. Information on suspensions of pesticide products is available on EPA’s website.