Throwing on pajamas and curling up with a magazine could mean exposure to chemicals banned several decades ago. New, unpublished research has found that traces of polychlorinated biphenyls – banned in the United States 35 years ago – are leaching out of clothing and printed materials from around the world.

PCB-11 was detected in nearly all samples of paper products sold in 26 countries and clothing sold in the United States. The findings shed some light on how the chemical, tied to yellow dyes, inks and paints, is finding its way into people’s blood, the air and waterways.

Because it is an unintentional byproduct of pigment manufacturing, the PCB-11 found in the consumer products is exempt from U.S. laws regulating the compounds.

“It’s out there in levels that are worrisome,” said Lisa Rodenburg, an associate professor of environmental chemistry at Rutgers University and senior author of the study.

“Even at the parts per billion levels, if you find it in almost everything you test, that means people are in almost constant contact," she said.

Health effects of exposure to traces of PCB-11 have not been studied. But unlike the old PCBs, it doesn’t accumulate in people or animals. The banned PCBs, which are so persistent they are still contaminating the environment, have been linked to reduced IQs, cancer and suppressed immune systems.

In the new tests, all 28 samples of non-U.S., ink-treated paper products, including advertisements, maps, postcards, napkins and brochures, contained PCB-11 in the parts-per-billion range. In the United States, 15 of the 18 paper products had it.

In addition, all 16 pieces of U.S. clothing contained PCB-11. Most were children’s items bought at WalMart stores but manufactured overseas, Rodenburg said. In one kids’ pajama top, the front, which had yellow printing on it, had 20 times more PCB-11 than the back, which was printed in red.

“PCB 11 is ubiquitously present as a by-product in commercial pigment applications, particularly in printed materials,” the authors from Rutgers University and Boston College wrote in a draft of the study, which has undergone initial peer review and is expected to be published this year.

All PCBs were banned in the United States in the late 1970s because they were building up in the environment and in the bodies of people and wildlife. But byproducts of manufacturing are allowed as “unintentional contaminants.”

Federal regulations “recognize that some products (e.g., pigments and dyes) contain inadvertently generated PCBs,” Environmental Protection Agency spokesperson Cathy Milbourn said in an emailed response.

Under federal law, these compounds “are defined as excluded manufacturing products or processes and are not regulated as long as they are reported to EPA and the PCB concentrations do not exceed specified limits,” she said.

The EPA is assessing PCB-11 to review potential risks, she said.

Most of the PCBs used in electrical equipment and as industrial solvents from the 1930s to 1979 were more highly chlorinated than PCB-11. Classified as probable human carcinogens, they are among the most well-studied contaminants in the world. Because of their high chlorination, they have remained in ocean and river sediments for decades, and have accumulated in the tissues of fish and marine mammals.

However, little is known about effects of PCB-11.

“Everyone has ignored the lower chlorinated congeners, primarily because they are not persistent and are relatively easily metabolized in the human body,” said Dr. David Carpenter, director of the Institute for Health and the Environment at the University at Albany-SUNY. But it’s a “very real and important issue,” he said.

Last year University of Iowa researchers reported that PCB-11 can disrupt cell signaling, and Carpenter and colleagues found that PCB-9, which is similar to PCB-11, was more toxic than other PCB compounds.

Rodenburg said that even though potential effects from exposure to parts per billion of PCB-11 are unknown, its apparent ubiquity is concerning.

While there has been no evidence of fish or wildlife contamination, studies suggest that people are widely exposed. Sixty percent of 85 women from East Chicago, Ind., and Columbus Junction, Iowa, had traces of PCB-11 in their blood.

The compound is “rapidly metabolized and excreted” so the fact that it’s showing up in people suggests that people are “constantly exposed,” said Rachel Marek, a postdoctoral researcher at the University of Iowa who studies PCB-11 but did not participate in the new study.

“If they are in the air and one breathes them in every day, there will be continuous exposure to what I suspect are very toxic substances,” Carpenter added.

People may be exposed by inhaling it, touching it or ingesting it, University of Iowa researchers wrote in a 2010 study

PCB-11 was found in nearly every air sample near 40 Chicago elementary schools in 2007.

Manufacture or use of paints may be a source of the airborne emissions. Researchers found more than 50 PCB compounds in 33 commercial paint pigments purchased from U.S. stores. Other PCBs also have been linked to pigment manufacturing. 

The contaminants are “definitely on the radar” of people in the paint industry, said Steve Sides, a vice president at the American Coatings Association, which represents paint manufacturers. “We’ve been aware of it and we’ve alerted the pigment manufacturers, but as of right now, it’s an unavoidable byproduct in these pigments.”

The PCBs are formed when hydrocarbons and certain salts are combined at high temperatures.

Sides said that coatings from overseas manufacturers seem to have higher levels of PCBs.

Manufacturing of yellow pigments, called diarylides, most associated with PCB-11 has largely shifted to Asia. U.S. manufacturers emitted 14 pounds of a chemical used in diarylides – 3,3'-Dichlorobenzidine – into the air in 2012, down from the more than 200,000 pounds emitted into air and water in 1988, according to federal data.

In China, tests of 24 yellow pigment samples collected from three manufacturing plants determined that “yellow pigment is a significant source…for the widespread pollution of PCB 11.” 

The compound also keeps showing up in U.S. waterways.

PCB-11 has been found in the New York-New Jersey Harbor and the Delaware River. In the Delaware River, the load of that compound was almost double the amount of total PCBs allowable under federal rules.

In recent years, PCB-11 also has been found in the Houston Ship Canal, the Rio Grande River and San Francisco Bay, and in water at several sites in the Great Lakes region

The new study reported that the chemical could be getting into waterways through the washing of clothes that contain the yellow pigments.

“The more studies that come out like this, we’re going to have to check out the biological impacts,” said Nukhet Aykin-Burns, an assistant professor of pharmaceutical sciences at the University of Iowa who analyzed PCB-11’s impact on oxidative stress in cells.

“Just because we stopped production of PCBs and regulate them doesn’t mean we don’t have to worry anymore," he said. "They’re still relevant and coming from different sources now.”

This article originally ran at Environmental Health News, a news source published by Environmental Health Sciences, a nonprofit media company.