4 out of 5 Americans face toxic exposure from oat-based foods like Cheerios and Quaker Oats

In recent years, a chemical once limited to decorative plants has quietly entered your pantry—likely through your morning bowl of cereal.

Known as chlormequat chloride, this plant growth regulator has become increasingly common in oat-based foods imported into the United States. While it helps crops grow shorter and sturdier for easier harvesting, studies are now raising serious concerns about its effects on human health.

A new pilot study by the Environmental Working Group (EWG), published in the Journal of Exposure Science & Environmental Epidemiology, found that four out of five Americans tested between 2017 and 2023 had chlormequat in their urine.

The detection rate climbed over time—69% in 2017, 74% from 2018 to 2022, and an alarming 90% in 2023. This sharp rise coincides with regulatory changes that allowed the chemical on imported food crops like oats and barley.

The presence of chlormequat isn’t just theoretical. Researchers sampled oat products sold in U.S. stores in 2022 and 2023 and found the chemical in 92% of the oat-based foods tested, including well-known brands like Cheerios and Quaker Oats. Among 20 oat-based products analyzed, all but one contained measurable levels of chlormequat. Even organic products weren’t completely exempt; one out of seven organic samples had low traces of the chemical.

Because chlormequat leaves the human body quickly—usually within 24 hours—its presence in urine signals recent and ongoing dietary exposure.

“We found a greater number of people were exposed in 2023, compared to earlier years, and at higher concentrations,” the EWG study noted.

Chlormequat chloride was first registered in the United States in 1962, but only for ornamental plants. In April 2018, the Environmental Protection Agency (EPA) under the Trump administration published food tolerance levels for the chemical on imported grains, including oats, wheat, and barley. Two years later, the allowable levels for oats were increased.

These decisions allowed chlormequat to enter the American food supply legally, even though domestic farmers are still prohibited from using it on food crops.

By contrast, countries like Canada, the United Kingdom, and members of the European Union have long approved the use of chlormequat on food crops. As a result, it’s frequently found in cereals and grains overseas, and now, increasingly, in U.S. households.

Concerns about chlormequat’s effects aren’t new. As far back as the early 1980s, Danish pig farmers reported fertility issues in animals fed chlormequat-treated grain. Those early red flags led to controlled experiments in animals. Female pigs on a chlormequat diet showed difficulty mating and disrupted reproductive cycles. Male mice exposed during development had lower sperm quality and decreased fertilization success in lab tests.

More recent animal studies have confirmed and expanded on these concerns. Rats exposed during pregnancy and early life had delayed puberty, reduced testosterone, smaller reproductive organs, and sluggish sperm. In fetal development studies, chlormequat disrupted growth and metabolism. One study even found that male rats exposed to chlormequat had lower weights in reproductive organs and reduced sperm motility.

Still, not every study agrees. Some animal trials found no clear effects on female mice or male pigs. Differences in species, dosages, timing of exposure, and the biological sex of test animals may explain the mixed findings.

“The evidence on chlormequat is still evolving,” researchers say, “but the toxicological data strongly support further investigation.”

The exact way chlormequat disrupts the body is not fully known. It doesn’t appear to act like classic endocrine-disrupting chemicals, which target estrogen or testosterone receptors. Instead, some studies suggest it might alter steroid hormone production or cause stress inside cells, known as endoplasmic reticulum stress.

While studies on humans are still scarce, chlormequat exposure may bring similar health concerns:

In occupational settings, such as farms or greenhouses, workers might inhale or absorb the chemical through the skin. But most people likely encounter it through their food, especially oat-heavy products.

Chlormequat’s short half-life—just 2 to 3 hours in the body—makes it difficult to assess long-term exposure through a single test. Still, its high detection frequency in both food and urine indicates that dietary exposure is frequent and ongoing.

Studies in the United Kingdom and Sweden have also shown near-universal detection of chlormequat in people tested there. In those nations, levels were often higher than those for other commonly studied pesticides like chlorpyrifos or pyrethroids.

While the chemical has been found in pig serum and milk, no human studies have explored its presence in blood or breast milk. That leaves big gaps in understanding how it may affect pregnant people or infants.

Given the evidence, scientists are urging U.S. regulators to take a closer look.

“These findings raise concerns about current exposure levels and warrant more expansive toxicity testing, food monitoring, and epidemiological studies,” the EWG report states.

For now, there's no official move to restrict or re-review chlormequat’s use in imported foods. But with detection rates and concentrations climbing, researchers say it’s time to reconsider how closely the chemical is monitored—and how much of it ends up in your breakfast bowl.

Note: Materials provided above by The Brighter Side of News. Content may be edited for style and length.

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