They collect dust in the back of your cupboard until you’re too lazy to run out to the grocery store. So you crack one open, plop it in a bowl and shove it in the microwave. Voila, dinner.

They’re also often used in school lunches across the country.

But a new study shows that people can be exposed to the industrial chemical Bisphenol A (BPA) by consuming canned foods — and that canned soups are the worst.

The study, published Wednesday in the journal Environmental Research, shows that canned soups and pasta can expose people to higher concentrations of the industrial chemical Bisphenol A (BPA) than canned vegetables and fruit. The study also found that canned beverages don’t expose people to BPA.

The chemical has been used for more than 40 years in consumer products. It’s used in the lining of cans to prevent metal corrosion. It has been linked to cardiovascular disease, diabetes, reproductive issues and other health effects.

“This knowledge can help guide consumers when making decisions as to which canned products they choose to buy,” Deborah Kurrasch, an assistant professor at the University of Calgary Cumming School of Medicine, told CNN. She was not involved in the study.

The new BPA study seems to be the most extensive to date. Between 2003 and 2008, researchers with the National Health and Nutrition Examination Survey, which is part of the Centers for Disease Control and Prevention, collected data on 7,669 people ages 6 and up in the United States. They logged what each person had to eat each day and took urine samples.

They found that people who had consumed one canned food item had 24 percent higher BPA concentrations in their urine than those who hadn’t consume any canned foods; the consumption of food items from two cans was associated with a 54 percent higher concentration.

Here’s where it gets really interesting. From CNN:

Once the researchers evaluated what types of canned foods were consumed, they found that eating canned soup resulted in a whopping 229% higher concentration of BPA compared with consuming no canned foods. Canned pasta resulted in 70% higher concentrations, and canned vegetables or fruit resulted in 41% higher concentrations.

Someone who eats a single can of cream of mushroom soup may still have a greater exposure to BPA than someone who eats three cans of peaches, [Jennifer Hartle, postdoctoral research fellow at Stanford University School of Medicine and lead author of the study] explained.

But what makes can soup so much worse? Hartle told the news outlet that it could be because soups need to be heated up a lot when it’s being processed. Also, it’s fattier.

CNN again:

“A canned soup — which oftentimes is solid and a liquid — usually needs a long heating time to get all of the contents to the same temperature needed to sterilize the food. Many canned beverages (beer, soda, juice) are acidic, so their thermal processing requirement is much different,” she said. “Another factor is that BPA partitions to, or moves into, solids. … Other key factors are the chemical composition of the lining and the fat content of the canned food, as BPA is lipophilic.”

Hartle led a previous study on children’s exposure to BPA. From the Stanford News Service:

A previous study led by Hartle found that children, who are especially susceptible to hormone disruption from BPA, are at risk from school meals that often come from cans and other packaging. This uptick in packaging is a result of schools’ efforts to streamline food preparation and meet federal nutrition standards while keeping costs low.

In 2015, as part of the Stanford Woods Institute for the Environment’s Rising Environmental Leaders Program, Hartle met with members of Congress who are working on regulating BPA in food packaging.

The U.S. Environmental Protection Agency states that BPA concentrations shouldn’t exceed 50 micrograms per kilograms of body weight per day.

The U.S. Food and Drug Administration (FDA) has restricted the use of BPA in baby bottles, sippy cups and the canned linings of liquid infant formula, but has yet to initiate a mass ban.

Lauren Sucher, a spokesperson for the FDA, told CNN, “The FDA has performed extensive research and reviewed hundreds of studies about BPA’s safety, and has determined that current authorized uses of BPA in food packaging are safe. The FDA continues to monitor literature and research on BPA.”

Hartle, in the Stanford News Service, noted that while companies are moving away from using BPA, there is little known about if synthetic BPA replacements are safe either.

Reach PublicSource web and interactives developer Natasha Khan at 412-525-0063. Follow her on Twitter @khantasha.

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Natasha is PublicSource's creative director. She runs the organizations visuals team, edits and produces interactive graphics, data visualizations and web packages for PublicSource. She manages the website...