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Why Receipts and Greasy Fingers Shouldn’t Mix

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“The chemicals used to make hand sanitizers, soaps, lotions, and sunscreen degrade the skin’s ability to act as a barrier"

An order of French fries may be bad for your health in ways that extend well beyond the outsize calorie count. According to a new study by scientists at the University of Missouri, people who used hand sanitizer, touched a cash register receipt and then ate French fries were quickly exposed to high levels of bisphenol A (BPA), a chemical widely used to coat receipt paper.

BPA has been identified as an endocrine disrupting chemical for its ability to interfere with estrogen and other hormones. In human and animal studies, BPA exposure has been linked to adverse effects on the reproductive and neurological systems as well as increased risk for obesity, diabetes and cardiovascular disease. Some animal studies also suggest that BPA can set the stage for certain cancers, including breast and prostate cancer.

The study, published in PLOS One, is the first to show how handling BPA-coated receipts can account for exposure at levels that have been shown to harm health.

Most studies of BPA exposure, including those that have informed current regulation of the chemical, have focused on exposure that happens through food or after BPA passes through the gut, explains study author Frederick S. vom Saal, Professor of Biological Sciences at the University of Missouri-Columbia.

But this study shows that skin absorption of BPA appears to lead to higher levels of biologically active BPA in the body than when the chemical is digested with food. When scientists added in two other factors—scrubbing hands with hand sanitizer and eating greasy food—the evidence points to a super-sized dose of BPA.

“The chemicals used to make hand sanitizers, soaps, lotions, and sunscreen degrade the skin’s ability to act as a barrier and so act as skin penetration enhancers,” says vom Saal. So BPA enters the body more efficiently than it would otherwise. Food grease and other oils can act similarly because BPA itself is fat-soluble, explains vom Saal.

Vom Saal also explains that BPA can be absorbed rapidly by tissue in the mouth so that the chemical enters the body without first being metabolized–or broken down in digestion.

“The combination of dermal and oral BPA absorption led to a rapid and dramatic average maximum increase in unconjugated (bioactive) BPA…in blood and urine within 90 minutes,” write the study authors. In experiments, BPA was absorbed by people who held a receipt for as little as two seconds. The amounts absorbed in the study “are in a zone where effects associated with obesity, diabetes and neurological effects can result,” says vom Saal.

Many laboratory studies have shown that BPA can produce health effects at very low levels of exposure—or just a few parts per trillion. BPA has also been shown to effect developing embryos, which means a mother’s exposure to BPA can affect her children. Some studies have shown that a single BPA exposure can affect even a third generation as the chemical has the potential to alter the ovary and eggs of the exposed fetus. At the same time many studies have found associations between BPA exposure in humans and the health effects found in lab studies.

Given the concern about BPA’s health effects, manufacturers of baby bottles and toddler’s sippy cups have largely stopped using it. In 2012, the U.S. Food and Drug Administration withdrew its approval for use of BPA in these products. But its use is still allowed in other products that come into contact with food. Industry trade associations, including the American Chemistry Council, maintain that BPA is safe and that average exposure levels, including from receipts, are not harmful.

Meanwhile, 12 different states have passed laws barring BPA in various products—primarily food and beverage containers intended for use by children. Only one state, Connecticut, has passed a law banning use of BPA in receipts.

But simply switching to another chemical may not solve the problem. As vom Saal and his coauthors point out in this study, a common BPA alternative used in receipts is bisphenol S, which can also interfere with estrogen. In fact, in its assessment of available alternatives for receipts, the U.S. Environmental Protection Agency found no chemical that was clearly safer than BPA. “What we need,” says vom Saal, “is an alternate technology.”

In the meantime, it appears that grabbing the fast food receipt before snacking on French fries may not only be packing on the extra calories. It might also be disrupting our hormones.

This post originally appeared on CivilEats.com.

Read next: Know What’s In Your Face Wash: Why Illinois Banned Microbeads

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