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Have you ever wondered why store receipts feel ever-so-slightly powdery? That’s because most receipts are printed on “thermal” paper, which changes color when heated. A thin coating of powder helps develop the dyes. That powder, it turns out, contains an endocrine-disrupting chemical, and we’re absorbing it through the skin on our fingers.

A study published Tuesday in the journal JAMA found that people who continuously handle store receipts wind up with significantly elevated levels of bisphenol-A, more commonly known as BPA, in their urine.

BPA has been used since the 1960s to line soup cans, and to make a wide array of plastic bottles and food containers. The chemical mimics human estrogen in the body, and can “disrupt” the body’s hormone, or endocrine, system, though what doses are considered harmful is a matter of debate. Studies link BPA to breast cancer, diabetes, and obesity, as well as hormone abnormalities in children. One study found that more than 90 percent of Americans have some level of it in their urine.

Whereas BPA in things like cans and bottles are “bounded,” or attached to other molecules that must break down for a person to absorb the chemical, the BPA in receipts is present in loose powder, which easily leaves a very high concentration of the chemical on peoples’ fingers. Dr. Shelley Ehrlich of Cincinnati Children’s Hospital Medical Center wanted to know how much of that actually ends up in our bodies.