Thermal receipts are the shiny paper slips commonly provided at retail checkouts. Unlike standard paper, these slips are coated with a chemical compound that reacts to heat, allowing printing without traditional ink cartridges. This specialized coating is a source of chemical contamination that can easily transfer onto the skin upon contact. Minimizing interaction with these common items is prudent due to the substances they contain and how they interact with the human body.
The Chemical Coating Used on Receipts
The distinct appearance and function of thermal receipt paper are due to a coating containing a colorless dye and a chemical developer. When the thermal printer applies heat, the developer reacts with the dye, causing the heated areas to turn dark and form the text and images.
The most common developer chemicals are bisphenols. The original chemical used was Bisphenol A (BPA), which is effective and inexpensive. Due to health concerns, manufacturers often replace BPA with Bisphenol S (BPS). Despite being marketed as “BPA-free,” BPS is also a bisphenol chemical that functions similarly in the coating.
These developer chemicals are present in high concentrations, often exceeding 1% of the paper’s weight. The bisphenol molecules are not chemically bound to the paper fibers; they exist as a loose coating that is readily transferable through brief physical contact.
How Endocrine Disruptors Enter the Body
Bisphenols on receipts are classified as endocrine-disrupting chemicals (EDCs). An EDC interferes with the body’s hormone system, which regulates processes like metabolism, reproduction, and neurological development. Bisphenols can mimic the structure of natural hormones, such as estrogen, disrupting the body’s chemical balance.
Exposure occurs mainly through dermal absorption, where the chemicals transfer directly through the skin. Research shows that cashiers, who handle many receipts daily, have higher levels of bisphenols in their bodies compared to the general population.
The rate of absorption is significantly increased when the skin is moist or when products like hand sanitizers and lotions have been recently applied. These products contain dermal penetration enhancers. Using an alcohol-based hand sanitizer immediately before touching a receipt can increase the transfer of BPA to the skin by up to 185 times.
Once absorbed through the skin, these chemicals enter the bloodstream directly. When BPA is ingested, it is largely metabolized and inactivated by the liver before it can circulate widely in the body. However, dermal absorption bypasses this initial liver metabolism, resulting in a higher proportion of the bioactive, or active, form of the chemical circulating throughout the body. Exposure can also occur through oral ingestion if the chemicals transfer from contaminated hands to the mouth.
Practical Steps for Minimizing Exposure
Minimizing contact with thermal receipts is the most effective way to reduce exposure, as the chemicals are easily transferred and absorbed. The simplest step is to opt out of physical receipts entirely by choosing digital or e-receipt options. This paperless choice eliminates the risk of contact.
If a physical receipt is unavoidable, handle it as little as possible, holding it lightly with only two fingers for the briefest time necessary. If the receipt must be kept, fold it inward so the printed sides touch. This limits the surface area that can contaminate a wallet or purse.
Avoid using hand sanitizer or lotion immediately before or after touching thermal paper, as this significantly boosts chemical absorption. The best practice after handling any receipt is to wash hands thoroughly with soap and water.