Thermal paper is a common material used for printing retail receipts, tickets, and boarding passes. This specialized paper is coated with a chemical compound that allows an image to appear when heat is applied, eliminating the need for traditional ink. The question of whether this ubiquitous paper contains Bisphenol A (BPA) has become a significant public health concern. BPA is a synthetic chemical widely used to manufacture polycarbonate plastics and epoxy resins, known primarily for its classification as a potential endocrine-disrupting chemical.
The Chemistry of Thermal Paper and Phenols
Thermal paper typically contains BPA, which functions as a color developer, or chromogenic agent. This agent is mixed with a colorless dye on the paper’s surface. When the thermal printer applies heat, the BPA reacts with the dye to produce the dark, visible text or image. This chemical application is favored by manufacturers because it is effective and relatively inexpensive.
Due to rising health concerns and regulatory pressure, many manufacturers have begun substituting BPA with chemically similar compounds. The most common replacement is Bisphenol S (BPS), which also belongs to the family of chemicals known as phenols. In a “BPA-free” thermal receipt, BPS performs the identical function as the color developer. This substitution means that while a receipt may not contain BPA, it likely still contains a related chemical that requires further scrutiny.
Routes of Exposure from Thermal Paper
The primary way the chemical coating transfers from the paper to a person is through direct skin contact, a process known as dermal absorption. Unlike chemicals bound within a hard plastic, the BPA and BPS in thermal paper exist in a free form on the surface, allowing them to readily transfer to anything they touch. Studies have shown that even briefly handling a receipt can lead to the absorption of these chemicals into the body.
The rate of dermal absorption can be significantly increased by certain factors. Handling thermal paper with moist, oily, or greasy hands can increase the amount of chemical absorbed. The use of alcohol-based hand sanitizers or lotions is a particular concern, as the alcohol acts as a solvent that enhances the skin’s ability to absorb the chemicals from the paper.
A secondary, though less direct, route of exposure is ingestion. After handling a thermal receipt, the chemical residue can remain on the hands and then be transferred to the mouth. This often happens by touching food, especially finger foods, or simply touching the face before washing hands. Cashiers and other workers who handle receipts frequently are especially susceptible to higher levels of exposure through both dermal and ingestion pathways.
Understanding the Health Implications of Low-Dose Exposure
The concern surrounding BPA and BPS stems from their classification as endocrine-disrupting chemicals (EDCs). Endocrine disruptors are substances that interfere with the body’s hormonal system. Both BPA and BPS are known to mimic the structure and function of the natural hormone estrogen, allowing them to bind to hormone receptors. This mimicry can potentially alter the body’s normal biological processes, even at very low exposure levels.
Low-dose exposure to these chemicals has been linked to potential adverse effects across several biological systems. In reproductive health, there are associations with reduced fertility and the disruption of fetal development, which is particularly concerning for pregnant women and young children. The estrogen-mimicking activity may also contribute to conditions like polycystic ovary syndrome (PCOS) and may be associated with certain hormone-sensitive cancers.
Metabolic function is another area of scientific investigation, with research suggesting links between bisphenol exposure and metabolic syndrome, obesity, and insulin resistance. Studies have also indicated potential neurological consequences, with exposure during developmental stages possibly leading to altered brain development and behavioral changes later in life. The fact that BPS shares a similar mechanism of action to BPA means that the health concerns regarding the substitute are often comparable to those of the original chemical.
Practical Steps for Reducing Contact
Consumers can take several proactive steps to minimize their exposure to the chemical coatings on thermal paper. The most effective action is to reduce contact by refusing a paper receipt altogether or by choosing an electronic or digital receipt option when available. If a paper receipt is necessary, avoid crumpling it into your palm and handle it lightly, ideally touching only the non-printed, uncoated side.
Since alcohol-based products increase absorption, it is advisable to avoid handling receipts immediately after using hand sanitizer or lotion. Thorough hand washing with soap and water immediately after handling any thermal paper is an important step to remove any transferred chemical residue. This is especially important before eating or preparing food.
Thermal paper receipts should not be placed in the recycling bin because the chemical coating can contaminate the recycled paper stream. Instead, they should be thrown in the trash to prevent the chemicals from re-entering the environment through the recycling process. For those who must save receipts, storing them in a dedicated envelope or bag can prevent the chemicals from transferring to other items, such as money or ID cards in a wallet or purse.