EPA Suspends the Use of Dimethyl Tetrachloroterephthalate Weed Killer

The Environmental Protection Agency (EPA) has issued an emergency order to suspend the use of a particular weed killer after it was linked to serious health risks in unborn babies. A move like this hasn’t happened for nearly 40 years — and EPA officials didn’t mince words when talking about the severity of using the herbicide dimethyl tetrachloroterephthalate (DCPA).

“DCPA is so dangerous that it needs to be removed from the market immediately,” Michal Freedhoff, assistant administrator for the Office of Chemical Safety for the EPA, said in a statement. “In this case, pregnant women who may never even know they were exposed could give birth to babies that experience irreversible lifelong health problems.” The order goes into effect immediately.

This isn’t the first time DCPA has come under fire this year. In April, the EPA warned that pregnant farmworkers and their babies could face “significant health risks” if they were exposed to DCPA. 

But what is DCPA, and why is it dangerous enough to warrant an emergency order? Here’s what you need to know, according to a toxicologist. 

What is dimethyl tetrachloroterephtalate (DCPA)?

Also known as Dacthal, DCPA is an herbicide that’s used on crops like Brussels sprouts, broccoli, cabbage, and onions. DCPA is “used to control annual grasses and broadleaf weeds,” says Jordan Kuiper, PhD, an environmental and prenatal/perinatal/pediatric epidemiologist at George Washington University’s Milken Institute School of Public Health.

“This was at one point discontinued in the U.S., and then another manufacturer ended up bringing it back on the market,” says Jamie Alan, PhD, an associate professor of pharmacology and toxicology at Michigan State University. 

The EPA specifically notes that it issued the emergency action because unborn babies whose pregnant mothers were exposed to DCPA could experience changes in fetal thyroid hormone levels. Those changes are typically linked to lower birth weight, impaired brain development, decreased IQ, and impaired motor skills later in life — and some of them are irreversible, per the EPA.  

“This chemical stays around for quite a while,” Alan says, adding that it’s also a “possible carcinogen.” 

Worth noting: DCPA has been banned for use on crops in the European Union since 2009.

How does DCPA get to humans?

People can be exposed to DCPA in a few different ways, including touching it, touching their eyes with hands that have been in contact with the herbicide, ingesting it, and drinking contaminated well water, Alan says. It’s also possible to inhale it, Kuiper says. 

The EPA estimates that some pregnant people who handled DCPA products could be exposed to amounts four to 20 times greater than what the agency has deemed safe for unborn babies.

The EPA also notes that entering or working in areas where DCPA has already been applied can be problematic for 25 days or more, which can be particularly dangerous for workers transplanting, weeding, and harvesting crops. 

“If someone lives near a farm using it, or if they are applying the product, they can be exposed,” Alan says. 

Unfortunately, DCPA residue can also linger on crops, and washing your produce doesn’t remove all traces of it. “This particular compound is very ‘sticky,’ meaning it can attach to surfaces,” Alan says. “It also has a long half-life, which means that it takes a very long time before it breaks down.”

Other ways to lower your exposure risk

DCPA is now banned from being used in crops, although it’s likely that many crops on the market right now have been exposed to it. To lower your exposure to DCPA, Alan recommends washing your produce “really well.” Kuiper also recommends removing the outer layer of leafy greens when possible. 

“Purchase produce that is labeled as ‘organic,’ even though organic produce may still not necessarily be pesticide-free,” Kuiper says. “It’s important for consumers to understand where their food comes from, where it’s grown, and whether it has been treated with any chemicals.”