What You Should Know About the EPA’s Decision to Remove DCPA From the U.S. Market

The first use of an emergency action to stop use of a pesticide in more than 40 years

The United States Environmental Protection Agency (EPA) is taking immediate action to stop the use of dimethyl tetrachloroterephthalate, a weedkiller known as DCPA or Dacthal. The August 6 order removed the herbicide from the market immediately. But why did this happen, and what does it mean for Americans?

What is DCPA and why should you care?

The rare use of this action highlights the serious health effects of DCPA. DCPA has been on the market since 1958 as an herbicide. Until the emergency action was taken, it was used to treat soil before crops are planted - mainly leafy green vegetables and onions. The herbicide has been shown to have toxic effects on the thyroid, leading to serious hormonal changes in fetuses that could result in low birth weight, impaired brain development, decreased IQ, and impaired motor skills.

The EPA classified DCPA as a likely carcinogen in 1995. In 2009, concerns around its toxic effects led the European Union to institute a ban. In 2023, the company that manufactures DCPA voluntarily terminated its use for turf applications to mitigate risks to the public.

Why are farmworkers and their families disproportionally affected?

Farmworkers serve an essential role in society by tending and harvesting the crops we all rely on. But this role comes with risks, especially from exposure to pesticides and herbicides like DCPA.

In the case of DCPA specifically, the product’s labeling did not include appropriate disclosures of its health risks. This limited users’ ability to protect themselves. When sprayed on crops, DCPA can also become airborne, extending the risks to other farmworkers and surrounding communities. Similar to other chemicals of concern such as PFAS and microplastics, DCPA presents an environmental justice issue as farmworkers are often lower-income individuals and largely Hispanic. The development of ethical supply chains is crucial in addressing these issues, ensuring that the health and safety of farmworkers are prioritized throughout the agricultural production process.

How long does DCPA remain in the environment?

An occupational risk assessment report by the manufacturer shows that levels of DCPA are unsafe for 25 days or longer after application. Further, the chemical is highly mobile and environmentally persistent, causing inadvertent exposure in soil and water for weeks after its use. Despite this, DCPA’s labeling only restricts entry into treated fields for 12 hours after application. In addition, a 2008 report on its health effects states that DCPA breaks down into other compounds that also persist in the soil and groundwater and can cause harm to human health.

Why did the EPA take emergency action?

The EPA rarely uses its emergency suspension authority to suspend the use of a product, and this represents the first time in over 40 years that emergency action has been used to stop the use of a pesticide. Several factors played into the decision, including the risk of irreversible damage to developing babies, the lack of a safe approach to applying the substance, misleading label uses that did not align with data about its lifetime in the environment, and uncertainty around toxicity information provided by the company. The compound breaks down in the environment much more slowly than suggested on the labeling, so exposure can still occur in tasks after application, such as weeding and harvesting. Also, a May 2023 assessment by EPA concluded that the exposure risk to farmworkers could not be lessened with proper use of personal protective equipment.

What can we do to protect ourselves?

Because of other high-visibility consumer safety concerns such as bisphenol A, PFAS, and toxic metals in children’s products and foods, consumers have been more engaged in understanding what chemicals are applied during food production and how to prevent exposure. Some best practices relevant to DCPA and compounds like it are:

• Consume products containing certified organic green leafy produce during pregnancy and for young children  if possible.
• Eat a variety of healthy foods and foods from a variety of sources to minimize your exposure to any single pesticide.

What we are doing at RTI to support environmental health research

As a large nonprofit research institute with environmental scientists, analytical chemists, toxicologists, environmental modelers, and other subject matter experts, we are at the forefront of research on chemicals in our environment and what we can do to advance environmental health outcomes. Some of our work includes:

• Developing analytical methods for detecting pesticide residues in food and environmental samples. This work contributes to more accurate monitoring of pesticide levels and helps support informed public health recommendations. Our advanced detection methods allow for better tracking of compounds like DCPA in our food supply and environment, enabling more effective risk management strategies and advanced understanding of pesticidal compounds like DCPA.
• Quantifying exposure hazards and assessing disproportionate health risks and benefits of agricultural inputs for crop health and food security. These findings can support efforts to educate the public about ethical supply chains and consumption.
• Evaluating occupational exposure to pesticides, particularly focusing on vulnerable populations such as farmworkers. This research has contributed to better understanding the pathways of exposure and developing more effective protective measures.
• Modeling the persistence and movement of chemicals in soil, water, and air to help predict long-term environmental impacts and inform policy decisions.