Source: Allied World Risk Management

On August 6, 2024, the U.S. Environmental Protection Agency (USEPA) announced an Emergency Order (see link below) for the suspension of all registrations of the preemergent herbicide1 dimethyl tetrachloroterephthalate (DCPA or Dacthal) under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA). The suspension of DCPA is based on the studies that have reported bodily injury (possible human carcinogen) associated with known and unknown exposures. The USEPA intends to issue a Notice of Intent to Cancel the DCPA products within the next 90 days.

In 1958, DCPA was initially registered for use (commercial and residential) as a pesticide to control weeds in both agricultural and non-agricultural settings. It’s primarily used on crops such as broccoli, brussels sprouts, cabbage, and onions. Additionally, DCPA is a general weed control for turf grasses at residential settings. Formulations of DCPA include an emulsifiable concentrate, a flowable concentrate, granular, soluble concentrate/liquid, and wettable powder.

DCPA is considered to be immobile and tends to sorb onto soil particles. Its degradation rate ranges from a few days to approximately 100 days depending upon the media. DCPA breaks down into Tetrachloroterephthalic Acid (TPA) and Monomethyl Tetrachloroterephthalic Acid [MTA]); both TPA and MTA are more soluble in water than DCPA.

Environmental and Human Health Exposures of the DCPA may include the following:

• Ambient Air via Spray Drift that impacts the inhalation pathway (reported to be a primary pathway for bodily injury);
• Soil Hot Spots attributed to its immobile properties;
• Dermal contact via workers or the public (e.g., children playing on impacted lawns/grass areas);
• Impacted groundwater through its degradation into TPA and MTA, which are soluble in water, and could create large plumes;
• Impacted Drinking Water via Public Drinking Water (ingestion) as public water systems do not typically test for DCPA, TPA, or MTA;
• Discharge to Publicly-Owned Treatment Works via Stormwater;
• Vapor Intrusion via volatilization; and
• Discharge via a National Pollution Discharge Elimination System into lakes, streams, ponds, estuaries, and oceans with potential Natural Resource Damage.

Possible Regulatory Developments

Based on the USEPA’s focus on DCPA, environmental investigations and/or remedial actions could be the next step in their regulatory process to reduce the DCPA environmental and human health risks. Upon the regulatory trigger of environmental actions, properties with historic environmental spills that have been closed could be re-opened should there be information leading to the former use of DCPA.

https://www.federalregister.gov/public-inspection/2024-17431/emergency-order-suspending-the-registrations-of-all-pesticide-products-containing-dimethyl

1Preemergent herbicides are a form of chemical weed control

Source

Roux Associates