Tattoo is a popular body art embraced by many as a medium of self-expression. Researchers now caution those planning to get inked to be aware that more than 80% of tattoo inks they examined in the U.S. contain mislabeled ingredients that could pose potential health risks.

The researchers from Binghamton University, New York, analyzed 54 tattoo inks from nine manufacturers in the country and found that 45 of them had unlisted additives and pigments.

"Major, unlisted adulterants include poly(ethylene glycol), propylene glycol, and higher alkanes. Many of the adulterants pose possible allergic or other health risks. Taken together, the results from this study highlight the potential for a significant issue around inaccurate tattoo ink labeling in the United States," the researchers wrote in the study published in the journal Analytical Chemistry.

Polyethylene glycol (PEG), commonly used to treat constipation, was the most prevalent unlisted additive in tattoo inks. Studies show that prolonged exposure to PEG can lead to adverse effects such as kidney or heart failure. The second most common additive was propylene glycol, linked to skin irritation and allergic reactions.

"More than half contained unlisted polyethylene glycol, which can cause organ damage through repeated exposure, while 15 contained propylene glycol, a potential allergen. Other contaminates included an antibiotic commonly used to treat urinary tract infections and 2-phenoxyethanol, which poses potential health risks to nursing infants," the news release stated.

The study has not examined if these ingredients were deliberately added or if they came through incorrectly labeled or contaminated materials used during manufacturing.

"We're hoping the manufacturers take this as an opportunity to reevaluate their processes, and that artists and clients take this as an opportunity to push for better labeling and manufacturing," John R. Swierk, senior author of the study, said.

"Despite the vast history of tattooing, and the increased frequency of tattoos in modern society, tattoo inks are generally not regulated by the government, nor does the government have any specific knowledge about the molecular composition of most tattoo inks," Sweierk wrote in his website.

FDA classifies tattoo inks as a type of cosmetics, and the pigments used in the inks are color additives that need premarket approval.

"However, because of other competing public health priorities and a previous lack of evidence of safety problems specifically associated with these pigments, the FDA traditionally has not exercised regulatory authority for color additives on the pigments used in tattoo inks. The actual practice of tattooing is regulated by local jurisdictions," an FDA fact sheet stated.