EWG finds little-known toxic chemical in four out of five people tested

A new EWG peer-reviewed study has found chlormequat, a little-known pesticide, in four out of five, or 80 percent, of people tested. The groundbreaking analysis of chlormequat in the bodies of people in the U.S. rings alarm bells, because the chemical is linked to reproductive and developmental problems in animal studies, suggesting the potential for similar harm to humans.

EWG’s research, published February 15 in the Journal of Exposure Science and Environmental Epidemiology, tested for the presence of chlormequat in urine collected from 96 people between 2017 and 2023. The chemical was found in the urine of 77 of them.

Our tests found higher levels and more frequent detections of chlormequat in the 2023 samples, compared to those from 2017 through 2022, which suggests consumer exposure to chlormequat could be on the rise. 

Just as troubling, we detected the chemical in 92 percent of oat-based foods purchased in May 2023, including Quaker Oats and Cheerios. The fact that so many people are exposed raises concerns about its potential impact on public health, since animal studies link chlormequat to reduced fertility, harm to the reproductive system and altered fetal growth.

Environmental Protection Agency regulations allow the chemical to be used on ornamental plants only – not food crops – grown in the U.S. But its use is permitted on imported oats and other foods sold here. Many oats and oat products consumed in the U.S. come from Canada. 

Chlormequat was not allowed on oats sold in the U.S. before 2018, when the Trump EPA gave first-time approval for some amount of the chemical on imported oats. The same administration in 2020 increased the allowable level. These regulatory changes might help explain why we’re seeing more frequent, higher detections of the chemical in Americans tested. 

In April 2023, in response to a 2019 application submitted by chlormequat manufacturer Taminco, the Biden EPA proposed allowing the first-ever use of chlormequat on barley, oat, triticale and wheat grown in the U.S. EWG opposes the plan. 

Our findings

For this study, EWG sourced urine samples collected between 2017 and 2023 from 96 people in the U.S. and tested them for chlormequat at a specialized lab in the United Kingdom. 

The chemical was detected in four out of five people tested – 77 of 96 – which shows exposure to chlormequat is likely widespread. These findings also suggest regular exposure, since we know chlormequat leaves the body in about 24 hours.

We found a greater number of people were exposed in 2023, compared to earlier years, and at higher concentrations. 

In 2022, EWG tests of food found high detections of chlormequat in oat-based products. To help us understand sources of exposure, in 2023, we tested 20 more oat-based foods for chlormequat, seven organic and 13 non-organic, as well as nine wheat-based products. 

Detectable levels of chlormequat were found on 92 percent of non-organic oat-based foods, while only two samples of wheat-based foods – both of them bread – had low levels. Only one of the seven organic samples had low levels of chlormequat.

Chlormequat’s potential harms

Some studies show chlormequat can damage the reproductive system and disrupt fetal growth in animals, changing development of the head and bones and altering key metabolic processes.

Although these studies focus only on the chemical’s potential effects on animals, they raise questions about whether it could also harm humans. 

Research about chlormequat’s effects is ongoing, and no studies have determined how much of a risk this chemical might pose. That’s where the government has a vital role to play in overseeing the future of chlormequat in the U.S.

What’s next?

EWG will continue to study the prevalence of chlormequat in Americans and its potential harmful effects on our health. We are also looking to the federal government for answers to questions such as:

• Should the Centers for Disease Control and Prevention add chlormequat to its biomonitoring program?
• Should the Department of Agriculture test oat samples for chlormequat? At one time it had suitable samples to test but never conducted tests.
• Should the Food and Drug Administration test U.S. food for chlormequat?
• Should the EPA should continue to resist calls to allow the use of the chemical on oats grown in the U.S.?

Until the government fully protects consumers, you can reduce your exposure to chlormequat by choosing products made with organic oats, which are grown without synthetic pesticides such as chlormequat.

You can also help keep chlormequat out of our food by joining EWG’s calls for the EPA to abandon its proposal to allow the use of this chemical on crops grown in the U.S.