A new report by the Environmental Working Group shows that paper receipts from grocery stores as well as restaurants, gas stations and automated teller machines contain the chemical bisphenol-A. The EWG said it found varying amounts of BPA in 40 percent of the receipts it tested.

Concern over the chemical has primarily centered on food and beverage containers. But scientists from the University of Missouri Division of Biological Sciences “found that the total mass of BPA on a receipt is 250 to 1,000 times greater than the amount typically found in a can of food or a can of baby formula,” the report said.

The report said that scientists had not determined how much of a receipt’s BPA coating can transfer to people’s skin and from there into the body by ingesting BPA through food or by touching their mouths.

The EWG said retail workers carry an average of 30 percent more BPA in their bodies than other adults, but that it is “unclear how much BPA-coated receipts contribute to people’s total exposure.”

The highest level of BPA was found in receipts at Safeway supermarkets. The highest concentration, 41 milligrams, was found in a store in Washington, D.C. A Safeway spokesman told the Washington Post the store was researching the issue and consulting with its paper receipt suppliers.

Scientists found 10.8 milligrams of BPA on a receipt in a Whole Foods Market store in Superior, Colo., according to the report. The EWG said it was one of 16 receipts (out of 36 tested) containing a "substantial" amount of BPA. Whole Foods had not responded to a request for comment by press time.

Receipts from a Sunflower Farmers Market in Boulder contained 0.145 milligrams, not considered a substantial amount in the report. The report said substantial amounts ranged from 41 milligrams to 2.98 milligrams.

"This is the first that we have heard of this,” said Chris Sherrell, president & chief operating officer of Sunflower Farmers Market. “Sunflower Farmers Market is and always will be committed to providing our customers and their families with the very best. We are concerned about this matter and are investigating the situation.”

Daniel Fabricant, vice president of scientific and regulatory affairs at the Natural Products Association, said from a scientific perspective, “there are still some questions. One study doesn’t make any conclusive decisions. We want to make sure the science is really done in total.”

But because of the concern over BPA now, he expects the market to respond. “I think you’ll probably see some folks coming out with BPA-free receipt paper.”

Appleton Papers, the leading manufacturer of the thermal paper used in receipts, no longer incorporates BPA in its receipts, the EWG said.