Some experts are raising a red flag after a component in rocket fuel was detected in food. Perchlorate, which is also found in missiles, airbags, explosives, and some types of plastic, was spotted in a range of foods in a new study published by Consumer Reports. 

For the study, researchers analyzed 196 samples of 63 supermarket products and 10 fast food items for the presence of perchlorate. Some foods were more likely to contain the chemical than others, with perchlorate being the most likely to show up in products classified as “baby/kid food.”

But what is perchlorate and how concerned about these findings should you be? Here’s the deal. 

What is perchlorate?

Perchlorate is a chemical compound with a variety of uses — and it’s indeed a component of rocket fuel, according to John D. Coates, Ph.D., director of the Energy & Biosciences Institute at the University of California, Berkeley. “Because it can be stored as a dry powder at atmospheric pressure, it is preferable as the primary oxidant to burn the rocket fuel,” he says. “In this use, it replaces oxygen.”

Perchlorate “can also be a breakdown product of bleach,” says Jamie Alan, Ph.D., an associate professor of pharmacology and toxicology at Michigan State University. Perchlorate is “highly soluble in water and quite mobile in soils and sediments,” Coates says. Because of this, it tends to spread easily in the environment, he explains.  

Some fertilizers contain naturally occurring perchlorate, says Andrea Kirk, Ph.D., a toxicologist and professor of Environmental and Occupational Health at the George Washington University Milken Institute School of Public Health. “These were widely used in agriculture and may be part of the reason why perchlorate is found in places that never had rockets,” she says. 

Which foods have perchlorate been detected in?

About 67% of the samples Consumer Reports tested had measurable levels of perchlorate, ranging from 2 parts per billion to 79 parts per billion. The researchers found that products classified as baby/kid food, fast food, and fresh fruits and vegetables had the highest levels. 

Foods in plastic containers also had high levels of perchlorate, followed by foods in plastic wrap and paperboard.

Worth noting: The Environmental Protection Agency (EPA) has established a safe exposure level for perchlorate of 0.7 micrograms per kilogram of body weight per day, but Consumer Reports says that many food safety experts think this number could be much lower. 

Perchlorate can also seep into water supplies, although food seems to be the most common way people are exposed, per Consumer Reports. 

What are the symptoms of perchlorate exposure?

Perchlorate has the potential to interfere with thyroid function, Coates says. “Ingestion can impact production of thyroid hormones, which are regulated by iodine, leading to hypothyroidism,” he says. Hypothyroidism is a condition that slows down the thyroid, leading to symptoms like fatigue, weight gain, a slowed heart rate, and depression, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). However, Coates points out that perchlorate is used to treat people with hyperthyroidism (i.e. an overactive thyroid). 

“Children, especially infants and developing fetuses will be more vulnerable,” Kirk says. “That is because thyroid hormones play important roles in brain development. Adults who are exposed to too much perchlorate may have effects that are reversible. But with babies, the damage can be permanent.”

Adults exposed to higher levels of perchlorate may end up having lower energy levels, coarse hair, and dry skin, Kirk says. “An infant may end up with a lower IQ than they would have had otherwise,” she says. 

How to protect yourself

A lot of the foods that contained perchlorate were processed and so-called “kid foods,” so limiting your intake of those may be helpful, Alan says. 

When it comes to perchlorate in your water, Kirk recommends checking your town’s water quality report — which should be available online — and see if they have information on perchlorate. “If levels are high, you can consider filtering your water,” she says. Just remember to check and see if a filter you’re considering can remove perchlorate.

But Kirk says that “it is very hard to know how much perchlorate might be in a food item.” Her advice: “The best thing you can do to limit exposure through food is to eat a varied diet.”