Laboratory tests found high levels of Bisphenol A (or BPA), a plastic hardener linked to breast cancer, heart disease, diabetes and other health problems, on 40 percent of cash register receipts.

The Environmental Working Group today reported that the BPA level found on thermal paper used to print store receipts was higher than those in infant formula, beverages and canned food.

The synthetic estrogen-like chemical was detected on receipts from major U.S. companies including McDonalds, Chevron, CVS, KFC, Whole Foods, Safeway, the U.S. Postal Service, Walmart, and the U.S. House of Representative cafeteria.

BPA reacts with dye to form black print on receipts handled by millions of Americans every day.

"A typical employee at any large retailer who runs the register could handle hundreds of the contaminated receipts a single day at work," said Jane Houlihan, the group's senior vice president for research.

The group collected 36 paper receipts from retailers in seven states and the District of Columbia and had them tested by the University of Missouri Division of Biological Sciences laboratory. Two-firths of the receipts were on thermal paper that was between .8 to nearly 3 percent pure BPA by weight, according to the scientists.

Receipts from some major chains, including Target, Starbucks and Bank of America ATMs, issued receipts that were BPA-free or contained only trace amounts.

Lab tests showed that BPA could easily rub off on someone’s skin who handled them. Scientists have not found exactly how much is absorbed into the body but said possible ways for BPA coating to get into the body is through oral exposure and dermal exposure.

BPA can move from receipt onto skin and then onto food and into the mouth. Previous study found that when BPA transfers from receipt to skin, it can penetrate the skin deeply so that it cannot be washed off. Once the chemical infiltrates the skin, there is a high chance that it can enter the bloodstream.

BPA can also be directly absorbed through the skin into the body. Scientists cautioned against using alcohol-based hands cleaners because the chemical could be absorbed more easily.

The Environmental Working Group recommends these tips for reducing BPA exposure from receipts:

* Minimize receipt collection by declining receipts at gas pumps, ATMs and other machines when possible.

* Store receipts separately in an envelope in a wallet or purse.

* Never give a child a receipt to hold or play with.

* After handling a receipt, wash hands before preparing and eating food (a universally recommended practice even for those who have not handled receipts).

* Do not use alcohol-based hand cleaners after handling receipts. A recent study showed that these products can increase the skin's BPA absorption.

* Take advantage of store services that email or archive paperless purchase records.

* Do not recycle receipts and other thermal paper. BPA residues from receipts will contaminate recycled paper.

* If you are unsure, check whether paper is thermally treated by rubbing it with a coin. Thermal paper discolors with the friction; conventional paper does not.