EPA Finalizes Cancellation of the Pesticide Dacthal

What is Dacthal?

Dacthal, also known as Dimethyl Tetrachloroterephthalate (DCPA), is a pre-emergent herbicide primarily used to control weeds in crops like onions, cole crops, and some ornamentals. The herbicide has been in use in the United States since the 1950s but has raised increasing health and environmental concerns due to its persistence in the soil and potential groundwater contamination.

Why Has the EPA Cancelled Dacthal?

The EPA's decision to cancel Dacthal stems from its reassessment under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), where the agency reviews products for safety and effectiveness. Concerns over DCPA's environmental impact and health risks, particularly groundwater contamination, led to an emergency suspension order in August 2024. With the registrant, AMVAC, opting to voluntarily discontinue the product, the EPA's final order formalizes this cancellation​.

Public and Organisational Responses

The cancellation has seen mixed reactions from various stakeholders:

• Earthjustice, representing groups like the Center for Food Safety and the Pesticide Action Network North America, expressed approval of the EPA's oversight. They urged the agency to ensure AMVAC's product return program prevents further exposure to harmful substances.
• AMVAC voiced disagreement with the EPA’s interpretation of certain regulatory procedures leading to the cancellation but chose not to contest the final order or withdraw their cancellation request.

Disposal and Stock Management Provisions

The EPA has specified guidelines for disposing of existing Dacthal stocks to mitigate environmental risks. Effective immediately, AMVAC is restricted from selling or distributing any remaining DCPA products, with allowances only for proper disposal or export under specific conditions. Retailers and users are advised to return unused products to their point of purchase. AMVAC has coordinated a collection program, directing end users to return Dacthal products to their original purchase locations, where the company will facilitate proper disposal​.

Future Implications

The EPA’s cancellation of Dacthal underscores a significant shift in pesticide regulation aimed at prioritising environmental safety and public health. As other pre-emergent herbicides are reassessed, stakeholders in the agricultural sector may need to consider alternative weed management solutions compliant with emerging regulatory standards.