A chemical linked to fertility problems in animals has been found in oats in the US. Should we be worried?

A new, peer-reviewed study from the Environmental Working Group (EWG) has determined that 80% of Americans are regularly exposed to the chemical chlormequat, which is linked to fertility and developmental issues in lab animals.

The chemical is used to control growth in grain crops such as oats, wheat and barley in order to make them easier to harvest.

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Here’s what you need to know about the findings.

What products have been found to contain chlormequat?

Chlormequat has been found in samples of conventional oat products including General Mills Cheerios and Quaker Old Fashioned Oats in levels exceeding 100 parts per billion. However, in the context of a 14-ounce box of cereal, for example, only a trace amount of the chemical would be present.

For 50 years, products with chlormequat residue were banned from US imports, and the chemical’s domestic use was limited to ornamental plants. But in 2018, the US Environmental Protection Agency (EPA) began allowing international imports of grain from countries where chlormequat is approved for use, including Canada and EU nations.

In 2020, the EPA increased the permissible amount of the chemical in imports from 15 to 40 parts per million, after petitioning from Taminco, a company that manufactures the chemical. Taminco has also submitted an application to the EPA to greenlight chlormequat’s use on US crops; if approved, the general population’s exposure to the chemical would probably increase.

How do chlormequat and other pesticides affect our bodies?

While concentrations of chlormequat in human urine are still well below current thresholds of concern, the EWG study authors found a “significant increase” of the chemical in 2023 urine samples from people living in Florida, South Carolina and Missouri, compared with samples from the last six years. Because chlormequat passes through the human body within 24 hours, the study suggests that these people are being regularly exposed to rising levels of chlormequat – probably through consumption of oat-based food items such as oatmeal and granola.

While acute ingestion of chlormequat can be fatal for humans, the impact of low, chronic doses is not thoroughly understood. Low levels of the chemical have been shown to affect reproductive health and growth in male and female lab animals.

“A precautionary approach should be used until more studies can investigate the potential health effects of chlormequat exposure in humans,” Dr Alexis Temkin, a senior toxicologist at the EWG and the study’s lead author, said via email. In addition, exposure to multiple chemicals can increase health risks, even if the dose of each individual chemical is below what regulatory agencies consider harmful.

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Many Americans are regularly exposed to harmful agricultural chemicals. Last November, Georgetown University published a paper analyzing the link between five decades of pesticide exposure and declining sperm health. A recent study by the Indiana University School of Medicine revealed a significant increase in the presence of the herbicide dicamba in pregnant people in Indiana: 70% tested positive between 2020 and 2022, a sharp rise from the 28% recorded in a similar study from 2010 to 2012. Dicamba is associated with certain cancers.

Last year, the Journal of the National Cancer Institute found that high levels of the herbicide glyphosate, commonly known by its original brand name “RoundUp”, in human urine was linked to oxidative stress, a condition that causes damage to DNA; the chemical is also associated with metabolic disorders and liver inflammation. Glyphosate has also been found in oat products.

How do I avoid ingesting chlormequat?

Does this mean you should nix your morning bowl of oatmeal? Not necessarily. The EWG, which is a non-profit but receives private sector support from some organic food companies, suggests consumers concerned about exposure to chlormequat and other pesticides may want to buy oat-based cereals and products made with organic ingredients, as certified organic oats are grown without synthetic pesticides. Low levels of contamination may still occur in organic products, but in the EWG’s testing “only one out of eight samples had low, detectable levels of chlormequat”, says Temkin.