FDA Study Finds Bacteria in One-Third of Tattoo Ink Products

Tattooing has been practised by humans as an art form for thousands of years.

We use needles to place meaningful images and marks on our bodies, piercing the protective skin barrier so that ink can be permanently deposited just beneath the epidermis.

Tattoo ink contamination is a persistent concern

Naturally, nobody wants potential pathogens introduced along with that ink. The tattoo industry has improved its sterilisation practices in recent years, but a 2024 US Food and Drug Administration study produced a troubling result: one-third of 75 sealed tattoo and permanent makeup ink products tested contained bacteria, including types that can make humans ill.

FDA researchers have now cast a wider net to determine whether that result was an anomaly.

Their retrospective review examined four FDA tattoo ink investigations conducted from 2018 to 2024. Of 259 unopened containers of tattoo and permanent makeup ink, one-third contained bacteria. In total, the testing recovered more than 250 bacterial isolates covering 94 species, including some known human pathogens.

In other words, the 2024 findings were not a one-off.

"These findings underscore that microbial contamination in tattoo and permanent makeup inks is widespread and diverse, reinforcing the need for sensitive molecular detection methods, expanded surveillance, and harmonized manufacturing standards to ensure product safety," writes a team led by FDA microbiologist Ohgew Kweon in a paper published in Scientific Reports.

Each of the four FDA surveys independently indicated that contamination of inks is a real concern, including among products marked as sterile.

However, the surveys had each assessed a specific product selection using a particular approach. This left several unresolved issues: the overall prevalence of contamination, whether certain product features could predict it, which microbes appeared repeatedly, and how much bacterial diversity had yet to be identified.

Perhaps the most important unanswered question was where, and by what route, the inks became contaminated. These were the gaps the researchers aimed to investigate.

They combined the earlier surveys to produce a dataset of 259 unopened tattoo and permanent makeup inks encompassing various brands, colours, and sterility claims.

For the original tests, the inks were opened in laboratory conditions. Genetic sequencing was then used to identify bacterial species in colonies cultured from the samples. This meant the analysis was detecting not merely tiny amounts of DNA, but bacteria viable enough to grow into colonies.

The new study applied one consistent analytical framework to all those results, allowing patterns to emerge that none of the individual datasets could have revealed.

Although contamination rates differed considerably across the four surveys, the combined estimated rate of bacterial contamination was 35.4 percent.

Sterile labels and product origin offered little protection

One result was especially notable.

A sterile label provided little indication that an ink was truly sterile. Nearly one-third of the 118 products labelled sterile - 30.5 percent - were contaminated. That compared with 35.5 percent of samples carrying no sterility claim.

Neither the type nor origin of the product appeared to offer a guarantee. Bacteria were present in 33.3 percent of tattoo inks and 33.0 percent of permanent makeup inks. Likewise, 33.5 percent of US-manufactured inks were contaminated, compared with 31.9 percent of imported products.

Whichever category the researchers considered, the proportion was roughly one-third.

More concerning still was the range of bacteria involved. The team found 94 species from 38 genera, with Bacillus overwhelmingly predominant. It was followed by Pseudomonas, Staphylococcus, and Lysinibacillus.

Of the 94 species detected, around one-third - 34 - are classed as potential pathogens because of documented links with human illness. They include Pseudomonas aeruginosa, Bacillus cereus, and Cutibacterium acnes.

This does not mean contaminated ink will inevitably lead to an infection. The research identified bacteria associated with disease, but it did not assess whether contaminated products had actually caused anyone to become ill.

"These findings are consistent with documented infection events and product recalls associated with microbial contamination introduced during ink manufacturing or distribution," the researchers write.

The full extent of tattoo ink bacteria remains unclear

The 94 identified species may not show the entire scale of the issue.

As sample numbers rose, so did the number of bacterial species found. Although the curve began to slow, it did not level off, suggesting that testing more samples could uncover additional bacteria.

The study was also restricted to species that can be readily grown in culture. Slow-growing and fastidious bacteria, along with viable-but-nonculturable bacteria, may not have been captured by the sampling.

For instance, there have been several reported outbreaks of tattoo-linked nontuberculous mycobacteria infections. The bacteria responsible can need specialised growth media and longer incubation periods than those used in these surveys.

The research also cannot establish when or how contamination happens. Sterility claims did not reliably predict it, nor did ink type, colour, or country of origin.

There is no clear measure available to consumers - or even practitioners - that would allow them to judge an individual bottle of tattoo ink as safe simply by looking at it.

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According to the researchers, the results point to deficiencies in existing manufacturing and quality-control practices. Their analysis indicates that manufacturers should use validated controls and sterilisation processes.

"These findings underscore the need for improved manufacturing quality control, validated sterilization procedures, and enhanced microbiological surveillance using complementary culture-based and molecular approaches to strengthen microbial risk assessment and improve the safety of tattoo and PMU ink products," the researchers write.

For anyone thinking about getting a tattoo, though, the guidance is largely unchanged. Investigate an artist carefully. An artist who follows rigorous hygiene procedures and keeps track of ink recalls and packaging integrity is probably a safer choice than your mate Jim's friend using a tattoo gun in his garage.

The findings were published in Scientific Reports.

This article was fact-checked by Rebecca Dyer and edited by Rebecca Dyer. Although we take pride in our process, we are only human. If you spot an error, please let us know.