BPA is a synthetic chemical compound used in polycarbonate plastics and epoxy resins. Public concern focuses on its presence in everyday items, particularly thermal paper receipts. Studies confirm that a significant percentage of retail receipts contain high concentrations of BPA or related chemicals. This loose chemical coating readily transfers from the paper surface to the skin, making the handling of receipts a direct pathway for exposure.
Why BPA Is Used on Thermal Paper
BPA is used on receipts because of the thermal printing method. This process relies on a chemical coating applied to the paper’s surface instead of ink cartridges. BPA acts as a color developer, or chromogenic agent, within this coating.
When the thermal printer head applies heat, it activates the coating, causing a reaction between a dye precursor and the BPA developer to create visible text and images. The chemical is not chemically bonded; it exists as a loose, fine powder mixed into the surface layer. This unbound nature allows for easy transfer upon contact. Some manufacturers use substitutes like Bisphenol S (BPS), but the underlying chemical function and potential for transfer remain similar.
Mechanisms of Dermal Absorption
BPA from receipts primarily enters the body through dermal (skin) absorption, not ingestion. Holding a receipt transfers the loose chemical onto the skin’s surface. From there, the compound passes through the outer layers and enters the bloodstream, bypassing the body’s detoxification mechanisms that typically process ingested BPA.
The rate and amount of transfer and subsequent absorption are significantly influenced by the condition of the skin. Handling a receipt with moist or oily hands, such as after eating, substantially increases the amount of BPA transferred. This effect is compounded when the skin’s barrier function is temporarily compromised.
The use of hand sanitizers or lotions dramatically increases the absorption rate. Many of these products contain alcohol or other penetration-enhancing ingredients that temporarily disrupt the skin’s lipid barrier. Studies indicate that using hand sanitizer can increase dermal absorption by a factor of 100 or more, as the chemical is more readily soluble and absorbed into the compromised skin.
When absorbed through the skin, BPA enters the bloodstream in its unconjugated, biologically active form. Ingested BPA, conversely, is largely metabolized and rendered inactive by the liver before circulating widely. The direct dermal route allows the active form of the chemical to reach sensitive tissues, making the exposure more biologically relevant.
Health Concerns Associated with Low-Dose Exposure
BPA is categorized as an endocrine-disrupting chemical (EDC), meaning it interferes with the body’s hormonal system. EDCs are concerning because they can mimic or block the action of natural hormones, such as estrogen, even when present at very low concentrations. The body’s signaling pathways are highly sensitive to these disruptions, particularly during developmental windows.
Chronic, low-level exposure from sources like receipts is linked to several potential health impacts. In terms of reproductive health, exposure has been associated with concerns such as altered fertility, polycystic ovary syndrome in women, and diminished sexual function in men. These effects stem from the compound’s ability to interfere with both estrogen and androgen signaling pathways.
Metabolic functions are also a concern, as exposure is linked to an increased risk of conditions like insulin resistance, type 2 diabetes, and obesity. Furthermore, low-dose exposure during pregnancy or early childhood may have long-term consequences for neurological development, influencing behavior and potentially increasing anxiety. The estrogen-like activity of BPA also raises concerns regarding hormone-sensitive cancers, including breast and prostate cancers.
The fact that BPA absorbed dermally circulates in its active, unconjugated state is a particular focus of caution among researchers. This active form is the one capable of binding to hormone receptors and initiating biological changes. Therefore, while the total amount of BPA absorbed from a single receipt may be small, the continuous nature of this low-dose exposure warrants careful consideration, especially for individuals who handle receipts frequently, such as cashiers.
Strategies for Reducing Daily Contact
Given the ease of dermal transfer, the most straightforward strategy for reducing exposure is to minimize physical contact with thermal receipts. Consumers should opt for digital or emailed receipts whenever that option is available. If a physical receipt is necessary, request that the cashier place it directly into the shopping bag to avoid immediate handling.
For those who must handle receipts, such as for expense tracking, they should be stored in a dedicated envelope or small pouch, kept separate from other items like cash or food. It is important to wash hands immediately and thoroughly with soap and water after handling thermal paper before touching food or the face. This action helps remove any transferred chemical residue from the skin.
Receipts containing bisphenols should not be placed in recycling bins, as the chemical can contaminate the entire batch of recycled paper products. Instead, they should be disposed of with regular trash to prevent the chemical from re-entering the paper stream. While some retailers use alternatives like BPS, these substitutes possess similar chemical structures and have also shown endocrine-disrupting properties, indicating they should be treated with the same caution as BPA-containing receipts.