DENVER -- If you're the type who has a wallet or purse full of receipts, you might want to throw them out. They could have the chemical Bisphenol A, or BPA, on them.

BPA has most recently been found in cans and water bottles. Water bottles from SIGG and Nalgene have both been recalled in recent years because they contain BPA.

Now, the Environmental Working Group says receipts from places like Safeway and Walmart also contain BPA and could be harmful to your health.

"You can't live in Denver and not be aware of BPA," said Julie Holly ,who has a 21-month-old son.

Holly admittedly is the type who hangs on to receipts to see how much she's saving.

"It does surprise me. I mean, I didn't think that paper had BPA in it. I thought that was limited to water bottles and plastic products," said Holly.

Fortunately for Holly, she shops at Target where receipts were found to be BPA-free. Starbucks is in the clear too.

But at McDonald's, KFC, Whole Foods, Safeway, Walmart and the U.S. Postal Service, lab tests found extremely high levels of BPA on receipts, according to the Environmental Working Group.

"It's probably not the best thing for young children or pregnant women," said Dr. Mark Anderson, chair of chemistry at the University of Colorado Denver.

Other experts say BPA can cause heart disease, diabetes and other developmental problems in small children.

"The biggest issue is you're handling it all the time. And the amount of BPA found on receipts is actually staggeringly high," said Anderson.

According to the Environmental Working Group, BPA reacts with dye on receipts or thermal paper to form what appears to be ink, even though it's just a dye reaction.

"Forty mg is a lot, but it's all in how much you handle it. It's not like you take this receipt and rub it all over your face or anything," said Anderson.

"We try to stay away from it," said Holly.

The Environmental Working Group is recommending checkout clerks who handle receipts regularly and often should be especially careful about washing their hands.

To check whether a receipt is thermally treated rub it with a coin. BPA receipts discolor with friction; conventional paper does not.