Planning to get tattooed? Know the risks beforehand, as researchers have detected bacterial contamination in many tattoo and makeup inks sold across the United States.

A new study published in the Journal of Applied and Environmental Microbiology by the American Society for Microbiology discovered that 35% of tattoo and permanent makeup inks sold in the U.S. are contaminated with bacteria. The researchers arrived at the findings after evaluating a total of 75 tattoo inks from 14 different manufacturers.

"Our findings reveal that unopened and sealed tattoo inks can harbor anaerobic bacteria, known to thrive in low-oxygen environments like the dermal layer of the skin, alongside aerobic bacteria. This suggests that contaminated tattoo inks could be a source of infection from both types of bacteria. The results emphasize the importance of monitoring these products for both aerobic and anaerobic bacteria, including possibly pathogenic microorganisms," corresponding author Seong-Jae (Peter) Kim, a microbiologist with the U.S. Food and Drug Administration, said in a news release.

With the rising popularity of body art, there have been increasing reports of tattoo-related infections. The latest study investigated the presence of both aerobic and anaerobic bacteria in commercial tattoo and permanent makeup inks under aerobic and anaerobic conditions.

To detect aerobic bacteria, researchers mixed 1 to 2 grams of the ink with a growth medium and incubated it. For tracing anaerobic bacteria, they used a similar process but incubated the mixture in an oxygen-free chamber filled with nitrogen, carbon dioxide, and hydrogen.

"Of 75 ink samples, we found 26 contaminated samples with 34 bacterial isolates taxonomically classified into 14 genera and 22 species. Among the 34 bacterial isolates, 19 were identified as possibly pathogenic bacterial strains," the researchers wrote.

Under anaerobic conditions, researchers discovered two bacterial species in the inks: Cutibacterium acnes (four strains) and Staphylococcus epidermidis (two strains).

"Both types of bacteria, those needing oxygen (aerobic) and those not needing oxygen (anaerobic), can contaminate the inks. There was no clear link between a product label claiming sterility and the actual absence of bacterial contamination," the news release stated.

Based on their findings, the researchers recommend continuous monitoring of these products to ensure safety and reduce the risk of complications.

"It should be noted that microbial infections constitute just one aspect of these complications. In addition to microbial infections, immunologic complications such as inflammatory reactions and allergic hypersensitivity, as well as toxic responses, represent a significant portion of these issues. In light of our study results, we want to emphasize the importance of continuously monitoring these products to ensure the microbial safety of tattoo inks," Kim added.