You may want to think twice about choosing a yellow item the next time you go shopping. The quintessential color of sunshine, happiness, and friendship is now linked to potentially serious health risks. According to preliminary findings from a peer-reviewed study, traces of the long-banned polychlorinated biphenyl (PCB), specifically PCB-11, has been found in yellow dye in clothing and printed materials, increasing people’s exposure and risk of adverse health effects.

PCB-11 is part of a class of toxic chemicals that were once used in industrial and commercial applications such as electrical, heat transfer, plastics, and rubber products, among many others. Although the chemical pigments were originally banned under the Toxic Substances Act in 1979, they are still allowed at very low levels. There are different types of PCB contaminants known to produce different effects, raising the question of uncertainty about the level of toxicity of the dyes. PCB-11 is a legal and different form of the chemical that can be found in yellow dyes, inks, and even paints.

These chemicals are considered to be a probable carcinogen because it is known to cause cancer in animals, while evidence for humans is not yet conclusive. To measure carcinogenicity in humans is difficult because chemicals cannot be fed to humans to see how they respond. However, observing humans who have been exposed to the chemical, and have a higher occurrence of cancer than most, could be indicative of cancer-causing PCBs. The Centers for Disease Control and Prevention says these chemicals have been linked to a higher risk of birth defects, irritations, cancer, and developmental issues in some children.

In a study to be published later this year, a team of environmental scientists at Rutgers University sought to unveil the most common items or consumer products in which the PCB-11 compound is found. Sixteen pieces of yellow-printed clothing, including children’s clothing purchased from Walmart were tested, as well as 28 samples of paper products, including postcards and napkins that contained ink and were made outside of the U.S.

The findings revealed 100 percent of the 16 articles of clothing had traces of PCB-11, 26 out of the 28 paper samples also tested positive, and 15 out of 18 paper goods made in the U.S. also contained the chemical. PCB-11 is found in everything from food packaging to plastic bags worldwide. "It's out there in levels that are worrisome," Lisa Rodenburg, senior author of the study told Environmental Health News. "Even at the parts per billion levels, if you find it in almost everything you test, that means people are in almost constant contact.”

A more worrisome thought is that even if consumers make an effort to avoid yellow-colored products, they will still be exposed to the toxins via air and water, which can eventually enter the human body. It is practically impossible to avoid touching printer materials like magazines, and even if this were done, everyone is going to be exposed to PCBs sooner or later. Rodenburg told ABC News, "The PCBs get out of that printed material and they get into the air, so whether you like it or not everyone is breathing this stuff in."

A previous study published in Environmental Science & Technology, found 60 percent of 85 percent of women in urban and rural communities in Indiana and Iowa tested for PCBs, had traces of PCB-11 in their blood. Despite the large environmental exposure difference, mothers and children in East Chicago, Ind., and residents in Iowa had the same PCB levels in their blood. PCBs can enter the human body by eating or drinking contaminated food, through the air we breathe, or by skin contact.

Rodenburg’s study just adds to the extensive scientific research that suggests PCBs are harmful not only to the environment, but to humans as well and can potentially be a threat even at low levels. It’s important to be aware there are some toxic chemicals that are legal and still around that can have adverse health effects. The study researcher recommends the U.S. Environmental Protection Agency to test toxic chemicals and then decide whether they can be safe. “It would make more sense if we tested them first and then decided whether they were safe to release into commerce to be used and sold."

Source: DeWall J, Hornbuckle KC, Marek RF, Thorne PS, Wang K. PCBs and OH-PCBs in Serum from Children and Mothers in Urban and Rural U.S. Communities. Environmental Science & Technology. 2013.