They are inside nearly every pantry. Cans are a convenient way to store foods for a long time.
But that convenience could come at a price.
A new study suggests that people could be exposed to a dangerous chemical called Bisphenol, or BPA, from the everyday consumption of canned goods.
BPA is widely used in plastics and it's also found in the lining of metal cans to extend shelf life.
A group of consumer and food safety advocates tested 50 cans from grocery stores and found 92% contained BPA.
The chemical, which experts say can leach into food, also mimics human hormones, and has been liked to cancer and developmental problems in animal studies.
The chemical's effect in humans is less clear, but the new report suggests the levels of BPA in canned goods might be especially risky for pregnant women.
"Just by eating a reasonable amount of food from cans a pregnant 20-something woman could ingest BPA at the same levels as have been shown to cause harm in lab studies," according to Elizabeth Hitchcock, U.S. Public Interest Research Group.
The report also found that BPA levels varied widely, even between the same products. Two cans of the same green beans in the study had dramatically different amounts of the chemical.
The Grocery Manufacturers of America point out that the chemical has been used in cans for decades. Many reviews have concluded the chemical is safe at low levels.
It and other industry groups oppose a ban on BPA, still several states have all passed laws restricting the use of Bisphenol A, and California Senator Dianne Feinstein is sponsoring a bill which would ban the use of BPA in food packaging nation wide.