The controversial chemical bisphenol A has been found in 40 per cent of receipts collected by the U.S. organization Environmental Working Group.

Scientists found BPA concentrations in receipts from thermal paper were 250 to 1,000 times greater than those found in food cans or plastic containers. (iStock)

There are concerns that BPA, as it is commonly known, can be harmful to human health.

In animal testing it was found to cause abnormal reproductive patterns, early puberty and diminished intellectual capacity, and it is thought to be associated with some forms of cancer.

In 2008, Canada became the first nation to take action by banning the import and sale of polycarbonate baby bottles containing BPA.

The chemical is used as a hardening agent in bottles and in the liners of food cans. Its presence in thermal receipts puts a new twist on how it might get into the human body.

'It's a concern that retail workers who are handling receipts all day long would be exposed to higher amounts.'—Dave Andrews, Environmental Working Group

A senior scientist with Environmental Working Group says the reason for concern is the amount of BPA found on receipts.

"The BPA is in much higher concentration in the receipt and much higher concentrations are available to be wiped off the receipts," Dave Andrews told CBC News.

The University of Missouri laboratory did the analysis on 36 receipts gathered from automated teller machines, and major retailers such as McDonald's, KFC, Wal-Mart and Safeway.

The total amount of BPA on receipts was 250 to 1,000 times the amount typically found in a food can or plastic bottle.

What's not clear is whether it poses any greater risk to human health than BPA which is ingested from other sources.

"There is still an open-ended question that's being researched in academic institutions on how much of that BPA from the receipt would actually make it into your body," Andrews said.

The research report shows that BPA can enter the body in two ways. It can leach through the skin or be ingested after being rubbed onto the hands.

People working in retail most exposed

Andrews told CBC News those who should be most concerned are people who work in the retail industry.

Some scientists say people should be wary of using plastic containers that contain BPA. (University of Cincinnati/Canadian Press)

"It's a concern that retail workers who are handling receipts all day long would be exposed to higher amounts," he said.

According to the Centers for Disease Control in the U.S., 93 per cent of Americans over the age of six have BPA in their bodies.

People working in the retail sector had 30 per cent more BPA on average than other Americans.

The EWG recommends people minimize the number of thermal receipts they collect at retail outlets ATMs and other machines where possible.

It also warns not to use an alcohol based hand sanitizer after handling a receipt as it causes greater absorption of the chemical.