The shiny, smooth paper used for most modern sales slips, like those from gas pumps, grocery stores, and ATMs, is thermal paper. This paper does not use traditional ink but instead relies on a chemical coating to create the printed image when heat is applied. While convenient for high-speed printing, this chemical coating is the source of public concern regarding potential health risks. The substances embedded in this paper are not bound to the paper fibers, making them easily transferable.
The Chemical Used in Thermal Paper
The primary chemical compound historically used in thermal paper is Bisphenol A (BPA). This substance acts as a color developer, reacting with a colorless dye in the paper’s coating when exposed to heat to produce the dark text and images you see on the receipt. Due to growing public awareness and regulatory action concerning BPA, many manufacturers began substituting it with a structurally similar compound, Bisphenol S, or BPS. Both BPA and BPS are part of the bisphenol family. They exist as a loose powder coating on the surface of the paper, meaning they are not chemically integrated into the paper structure itself. This lack of chemical bonding is what allows the substance to rub off easily onto anything that makes contact with the receipt.
How Exposure Occurs Through Handling
The main route through which these chemicals enter the body is dermal absorption. When a person handles a thermal receipt, bisphenol molecules are transferred to the fingers and palms. The amount of chemical transferred and absorbed is dependent on environmental and personal factors. Moisture on the skin, such as sweat, significantly increases the transfer rate of bisphenols, and oily substances like hand lotions or alcohol-based hand sanitizers can dramatically increase absorption, sometimes by up to 100 times. After the bisphenol is transferred to the hands, secondary exposure risks occur through hand-to-mouth transfer, which is a particular concern for children.
Disrupting the Body’s Hormonal System
Both BPA and BPS are classified as endocrine-disrupting chemicals (EDCs) because their chemical structures allow them to mimic natural hormones, specifically estrogen. By binding to the body’s estrogen receptors, they disrupt signaling pathways, which can lead to consequences even at low-dose, chronic exposure levels. Disruption of the endocrine system is linked to effects on metabolism, potentially contributing to conditions like obesity and Type 2 diabetes. Bisphenols can affect reproductive development and function due to their estrogen-like activity. Furthermore, exposure has been linked to interference with neurological development, especially during sensitive developmental periods in infants and fetuses.
Simple Measures to Reduce Your Exposure
The most direct way to limit contact is by declining a paper receipt whenever possible. Many retailers now offer digital receipts that can be emailed or texted, which eliminates the physical handling of thermal paper entirely. If a paper receipt is necessary, try to touch only the back, unprinted side, as the chemical coating is concentrated on the thermal-sensitive front. It is most important to wash your hands thoroughly with soap and water immediately after handling any thermal receipt, especially before eating or preparing food. You should avoid storing receipts in places where they can contaminate food, such as near groceries or in a kitchen area. Finally, be aware that alternatives marketed as “BPA-free” often contain BPS, which carries similar hormonal disruption risks. Some companies are now shifting toward phenol-free paper, using developers like Vitamin C, which represents a safer option.