When you get a tattoo, do you know what you're putting under your skin? New research shows the ingredient labels on most tattoo inks in the United States don't match what's actually in the bottle.
The study, recently published in the journal Analytical Chemistry, analyzed tattoo inks from nine manufacturers in the US and compared their actual contents with the label. The manufacturers ran the gamut from major, global companies to smaller producers, and the inks in question came in six colors.
Of the 54 inks, 45 of them — 90% — had major discrepancies with the labeled contents, such as different pigments than the ones listed or unlisted additives, according to the study.
More than half contained unlisted polyethylene glycol, which can cause organ damage through repeated exposure, while 15 contained propylene glycol, a potential allergen, the study shows. Other contaminates included an antibiotic commonly used to treat urinary tract infections and 2-phenoxyethanol, which poses potential health risks to nursing infants, the study noted.
The researchers pointed out that they were unable to identify whether unlisted ingredients were added intentionally or if the manufacturer was provided with incorrectly labeled or contaminated materials.
"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," Binghamton University Assistant Professor of Chemistry John Swierk, who led the research team, said in a statement.
Potential risks associated with tattoos usually focus on skin cancer and the pigments themselves, but additives can also cause risks — including some beyond the skin, the study noted. Side effects might not emerge until weeks or years later, making it difficult to determine exactly what reaction is happening and why.
Allergic reactions are the most common negative outcome, and they can be persistent, painful and even disfiguring, Swierk said. Red pigments are a particular problem, although science hasn't yet determined why.
Historically, tattoo inks have been underregulated in the US market. They've only been subject to regulation by the Food and Drug Administration since late 2022, after Congress passed the Modernization of Cosmetics Regulation Act.
"The FDA is still figuring out what that is going to look like and we think this study will influence the discussions around MoCRA," Swierk said. "This is also the first study to explicitly look at inks sold in the United States and is probably the most comprehensive because it looks at the pigments, which nominally stay in the skin, and the carrier package, which is what the pigment is suspended in."