Say goodbye to hidden hazards in the checkout aisle.
In a groundbreaking development, researchers have invented a safer alternative to the special paper used to print receipts that is completely free of so-called “forever chemicals.”
These man-made substances have been linked to a wide range of health problems, including certain cancers, hormone disruption, reproductive issues, metabolic disorders and abnormal fetal development.
That could spell trouble for the millions who regularly handle thermal paper, which relies on a colorless dye and a heat-sensitive “developer” to produce dark text without ink or toner.
For decades, the most common developers have been bisphenol A (BPA) and, more recently, bisphenol S (BPS). Both chemicals have been detected in the water and soil, and they can accumulate in the bodies of people who frequently touch receipts.
Regulators and manufacturers have long been searching for replacements, but progress has been slow. Any new option must react at the right temperature, remain stable during storage, mix well with other coatings, avoid background discoloration and remain affordable.
Now, Swiss scientists may have cracked the code with help from an unlikely source: wood.
“We have developed thermal paper formulations — which are commonly found in daily products like cash receipts, package labels, airline tickets, etc. — made from plant-based molecules that have very low or no toxic signatures,” Professor Jeremy Luterbacher, one of the lead chemists, said in a press release.
The team focused on lignin, a major component of wood that naturally contains chemical groups capable of acting as color developers.
Normally, lignin is too dark and chemically messy for printing, but the scientists developed a method to extract light-colored polymers while keeping the reactive properties intact.
To make the lignin responsive to heat, they added a ‘sensitizer.’ Rather than a petroleum-based chemical, though, they used diformylxylose, a sugar-based compound derived from plants.
When coated onto paper and tested, the new formulation produced clear, durable printed images that held up even after a year of storage.
While the contrast isn’t as high as the best commercial papers, the scientists said its performance matches existing BPA-based thermal papers on the market.
The lignin-based thermal paper also offered a major safety advantage.
BPA and BPS are known endocrine disruptors that mimic estrogen and can upset hormonal balance. When you handle a receipt, ticket, shipping label, medical record or other thermal paper product, these chemicals can transfer to your skin and enter the bloodstream.
In fact, research published earlier this year found that paper receipts from major retailers in the US are so loaded with BPS that holding one for just 10 seconds can expose your skin to enough of the chemical to exceed California’s safety limits.
While studies are ongoing, animal and lab research has identified potential links between bisphenols and fertility problems, early puberty, miscarriage and birth defects.
They may also contribute to neurobehavioral issues like anxiety, metabolic disorders including diabetes and obesity, cardiovascular problems such as high blood pressure and hormone-sensitive cancers affecting the breast, prostate, liver and uterus.
When the researchers compared regular BPA-based paper to their lignin version, they found the lignin paper triggered far less hormone-mimicking activity. The sugar-based sensitizer also showed no signs of toxicity or hormone-related effects in tests.
“Overall, the proposed formulations not only provide a viable and promising pathway toward safer and bio-based thermal papers but also showcase the potential of functionalized and preserved natural structures for formulating cheap and safe renewable products for everyday use,” the study authors wrote.
Looking ahead, the researchers said more work is needed to improve the print quality of lignin-based paper and scale up production to meet high demand.
The global thermal paper market, worth roughly $4 billion in 2022, is projected to hit $6 billion by 2030.
