Why is this largely unknown pesticide showing up in our bodies?

Researchers found chlormequat — a little-known pesticide with potential health impacts — in 77 out of 96 people tested, according to a new study.

The study, led by scientists at the Environmental Working Group and published today in the Journal of Exposure Science and Environmental Epidemiology, is one of the first in the U.S. to examine levels of the chemical in people and is concerning as previous animal lab studies found it negatively impacts reproduction and post birth health, and impairs proper weight and bone development.

“The ubiquity of this little-studied pesticide in people raises alarm bells about how it could potentially cause harm without anyone even knowing they’ve consumed it,” said Alexis Temkin, lead author of the study and toxicologist at the Environmental Working Group, in a statement.

While the U.S. Environmental Protection Agency (EPA) does not currently allow chlormequat use on any food crops, in 2018 the Trump administration approved its use on imported oats and, two years later, increased the allowable level on food from 10 parts per million (ppm) to 30 ppm.

In the new study, researchers tested the urine of 96 people between 2017 and 2023 for the pesticide, and found it in 77 people. Levels were higher in 2023 compared to previous years, suggesting exposure is on the rise.

Previous research from EWG found the pesticide in 92% of oat-based foods, including in Quaker Oats and Cheerios.

In April last year, Taminco, which manufactures chlormequat, asked the EPA to allow the chemical on U.S.-grown barley, oats and wheat. The EPA proposed allowing the change, but the proposed rule isn’t finalized.

“The federal government has a vital role in ensuring that pesticides are adequately monitored, studied and regulated,” Temkin said. “Yet the EPA continues to abdicate its responsibility to protect children from the potential health harms of toxic chemicals like chlormequat in food.”