Till receipts and paper money indicate the presence of high levels of bisphenol A (BPA), a chemical that is associated with cancer and early puberty.
The chemical mimics the female hormone oestrogen and scientists have long suggested it poses a risk to health - especially to young children.
In the latest research, a team from two U.S campaigning groups tested till receipts made from thermal paper that they had collected from 22 popular retailers and cafes in America.
They found that half of them were coated with large quantities of BPA. The chemical is used to make ink visible on thermal till receipts.
Holding the receipts for just 10 seconds caused up to 2.5 micrograms of BPA to transfer from the paper onto a person's fingers.
Meanwhile rubbing the receipts increased the amount of BPA transferred from the receipts onto fingers around 15-fold.
"Since BPA in thermal paper is present in a powdery film, we suspected it could easily travel from those receipts to other objects," the Daily Mail quoted the researchers as saying.
The researchers from the Washington Toxics Coalition and Safer Chemicals, Safer Families group, found the chemical on 21 of 22 bills tested, although in much lower levels than on the till receipts.