Only a very small minority of studies appear to support the U.S. government’s assertions that there were no effects of BPA at low doses. Where is the disconnect? Governmental regulatory agencies determine safety levels of chemicals by sticking tubes down into the stomachs of lab animals. In these types of tests, BPA is released directly into the stomach, where it goes to the liver to be detoxified into an inactive form called BPA-glucuronide. So, very little active BPA gets into the bloodstream. But, that’s not what studies on humans show. People have active BPA in their blood. How did the FDA respond? By rejecting all such human studies as implausible.
The problem with a “blanket rejection” of human data is that there may be sources of BPA exposure that are not modeled by stomach tube exposure in rats. After all, we don’t eat through a tube into our stomachs. Instead, we chew food and move it around in our mouths before it enters the stomach. It turns out that BPA can be absorbed directly into the bloodstream through our mouths, thus bypassing instant liver detoxification. The same would be the case for BPA absorbed through the skin.
Thermal paper, often used for cash register receipts, luggage tags, and many bus, train, and lottery tickets, is 1–2 percent BPA by weight. Taking hold of a receipt can transfer BPA to our fingers, especially if they’re wet or greasy. Does the BPA then get absorbed into our system through the skin? A study published in Environmental Health Perspectives found cashiers had more BPA flowing through their bodies “[c]ompared with other occupations.” That small study, however, was based on only 17 people. Another small study found strict vegetarians had lower urinary BPA concentrations compared with nonvegetarians. But again, the sample size was too small to really make a conclusion. It’s been estimated that even cashiers handling receipts all day may not exceed the “tolerable daily intake” of BPA—however, that could change if they were using something like hand cream.
Indeed, many skin-care products, including hand sanitizers, lotions, soaps and sunscreens contain chemicals that enhance skin penetration. So, using a hand sanitizer, for example, before touching a receipt could weaken the skin barrier.
What’s more, a study published in PLoS One found “using hand sanitizer and handling a thermal receipt…prior to picking up and eating food with [our] hands” results in high blood levels of active BPA.
Researchers at the University of Missouri, conducting a study to mimic aspects of the behavior of people in a fast-food restaurant, found that when people handled a receipt right after using the hand sanitizer Purell, BPA was transferred to their fingers. Then, BPA was transferred from their fingers to their fries, and the combination of absorption through the skin and mouth led to significant levels of active BPA in their blood.
We can hold a receipt in our hand for 60 seconds and only come away with 3 micrograms of BPA in our body. In contrast, if we pre-wet our hands with hand sanitizer, we can get 300 micrograms in just a few seconds—a hundred times more BPA.
“These findings show that a very large amount of BPA is transferred from thermal paper to a hand as a result of holding a thermal receipt for only a few seconds immediately after using a product with dermal penetration enhancing chemicals,” found the study. This could explain why dozens of human studies show active BPA in people’s systems, contrary to the assumptions based on stomach tube studies in rodents.
When actual evidence contradicts your assumptions, you reject your assumptions. The FDA, however, rejected the evidence instead.
Dr. Michael Greger is a physician, New York Times bestselling author, and internationally recognized speaker on nutrition, food safety, and public health issues. A founding member and Fellow of the American College of Lifestyle Medicine, Dr. Greger is licensed as a general practitioner specializing in clinical nutrition. This article is re-published from NutritionFacts.org