Environmental Working Group (EWG) has tested samples of cash register receipts from a variety of stores and other places of business. Results of this testing indicated that 40 percent of these cash register receipts had high levels of BPA.
BPA is an endocrine-disrupting chemical found in many food and beverage containers.
"The tests also showed that the BPA on the receipts could easily rub off onto the hands of anyone who handles them. That’s a potential worry for shoppers but even more so for the tens of thousands of store and restaurant workers who handled hundreds of receipts daily. Federal data analyzed by EWG shows that retail workers carry an average of 30 percent more BPA in their bodies than other adults."
The good news is, not all receipts showed BPA, so that means it's possible for businesses to purchase and provide paper that doesn't contain BPA.
Since BPA-tainted receipts are still being distributed however, you can identify whether or not your receipt has BPA. Rubbing it with a coin will cause a BPA receipt to discolor. The color of a clean cash register receipt won't be changed.
http://www.ewg.org/kid-safe-chemicals-act-blog/2010/07/a-little-bpa-along-with-your-change