American Chemical SocietyThermal receipts, center, are by far the leading source of BPA in paper products, followed by tickets, newspapers and fliers. Experts worry about people who handle them all day.
Over eight billion pounds of bisphenol-A, a chemical compound used in making plastic products and the linings of tin cans, are produced annually worldwide. Known as BPA, the substance turns up in human tissues, too.
Because the chemical can leach out of products and into food, diet is the most obvious means of human exposure. However, recent research shows that the chemical can be absorbed into human skin in a less familiar way: the handling of receipts.
“If we see BPA every day, and it accumulates in our bodies, it might pose a risk,” says Chunyang Liao, an environmental scientist with the New York State Department of Health and an author of a study in the journal Environmental Science and Technology on the substance’s presence in paper.
In the thermal receipts now routinely given out by stores, BPA is often used as a color developer for the printing dye. Such receipts have a thermal-sensitive layer that, when heated, produces color. Beyond cash register
receipts, high levels of BPA are also often present in the thermal paper used to make baggage destination tags, cigarette filters, and bus, train and lottery tickets.
About 30 percent of the thermal paper enters the paper recycling stream, which can introduce BPA into products like toilet paper, napkins and food packaging. Traces of the chemical
are found in the air and in water, soil, food and sewage.
“One thing that’s still surprising is that all the uses of BPA that people may be exposed to are still not fully accounted for,” said Sonya Lunder, a senior analyst for the Environmental Working Group, a Washington-based advocacy organization.
BPA is an endocrine disrupter, mimicking the body’s hormones. Studies on animals have suggested that it can have harmful effects on the reproductive, developmental and other systems, causing neurological problems, for example, or stimulating obesity.
Ms. Lunder said that studies financed by BPA-producing industries often indicate that the chemical does not cause any adverse effects in animals, while those undertaken by private scientists show the opposite.
Many states are considering a ban on BPA in food containers, especially those used by infants. In June 2009, Connecticut became the first state to ban the chemical in reusable food and beverage containers and in containers for infant formula and baby food.
Tests measuring levels of BPA in humans and the environment so far show levels to be below those causing adverse effects, although some researchers are nonetheless worried about the lower concentrations.
“Studies in animals show that very low concentrations of BPA can induce some response at the cellular level, so more attention should be paid to this chemical,” Dr. Liao said.
In March 2010 the Environmental Protection Agency declared BPA to be a chemical “of concern.”
For their study, Dr. Liao and his co-author, Kurunthachalam Kannan, analyzed 103 thermal receipts collected from cities in the United States, Japan, South Korea and Vietnam in 2010 and 2011. They also examined 99 samples of other paper products found in those countries, like mailing envelopes, magazines and printing paper.
They found BPA in 94 percent of the receipts they tested. Japan, which largely phased out the chemical in 2001, was the only country in which traces did not turn up in any samples.
Although chemical concentrations were higher in South Korea and Vietnam than in the United States, 100 percent of the receipts collected in the United States contained BPA — even some marketed as “BPA-free.”
“Many companies haven’t addressed this issue at all,” Ms. Lunder said. She pointed out, however, that the presence of the chemical in some receipts could result from the contamination of the paper base through recycling.
Receipts had the highest chemical content by far, followed by tickets, newspapers and fliers.The researchers wrote that BPA in receipts accounted for about 98 percent of consumer exposure from paper, and said they were particularly concerned about cashiers and other people who handle thermal paper on a regular basis.
“I think for general people, there’s no need to worry about BPA from paper since people receive far more exposure through their diet than from paper,” Dr. Liao said. “But we need to understand levels of exposure for people working with cash registers, for example.”
The federal National Toxicology Program is conducting a study of cashiers to measure levels of the chemical in their bloodstream before and after their work shifts.
Previous studies have shown that 27 percent of the BPA that finds its way to skin surfaces penetrates and reaches the bloodstream within two hours.
“This is a very different kind of toxicological exposure,” Ms. Lunder said. “BPA is going right into the bloodstream in a free, unmetabolized and more active state, which is different than consuming it through diet.”
The chemical can account for up to 3 percent of a receipt’s weight. The authors estimate that thermal receipts contribute about 33.5 tons of the chemical to the environment each year in the United States and Canada combined.
Last year the Environmental Protection Agency’s Design for the Environment program began looking into alternatives to using BPA in thermal receipts. So far 19 alternatives have been evaluated, and the results are expected next May.
One alternative might be issuing electronic receipts, Ms. Lunder suggested.
In future studies, Dr. Liao plans to investigate the transfer of the chemical from paper products into the air and food, and any resulting human exposure. “Many sources of BPA are still not known, so we are probably
underestimating exposure,” he said.
An earlier version of this post misstated the amount of bisphenol-A produced annually worldwide. It is eight billion pounds, not eight million.