A recent report by the activist organization Environmental Working Group found that American consumers had high levels of a chemical that has been linked to infertility, low fetal growth, and delayed puberty.

The chemical is called chlormequat and is used on oat plants to prevent them from bending over, which makes harvesting more efficient. Last year, the Environmental Protection Agency proposed allowing the use of chlormequat on U.S. food crops such as oats, wheat, and barley, but that decision has not been finalized. Currently, it is only used in foreign countries, some of which import oats to the United States.

Imported grains were first allowed to contain the chemical under former President Donald Trump in 2018. Trump’s administration increased the allowable limit in 2020.

“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,” the report states.

The Environmental Working Group (EWG) tested samples of various oat-containing products, including Cheerios cereal and Quaker Oats, and found high levels of the chemical in both products. A study analyzing the urine of humans between 2017 and 2023 also showed a rapid spike in chemical contamination. Chlormequat was detected in 69% of samples in 2017 but was found in 90% of samples in 2023.

“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,” wrote the report’s authors.

The health risks to humans exposed to high levels of chlormequat are unknown, but studies conducted on mice have shown a variety of reproductive issues, which the report said “raises questions about whether it could also harm humans.”

The EWG said it tested more than 20 oat-based products, including 13 non-organic and seven organic products, along with nine wheat-based products. Ninety-two percent of the non-organic oat-based products had high levels of chlormequat, while just two wheat-based products tested with low levels. Only one of the organic samples had low levels of the chemical.

The EWG is now pressing the U.S. Food and Drug Administration to block the use of chlormequat on U.S. grains until more studies can be conducted and a safe baseline is established. In the meantime, the group recommends that consumers choose organic products, which are less likely to have high levels of the chemical.