New research by the Centers for Disease Control and Prevention (CDC) offers another reminder for tattoo parlor patrons to take precautions against potential risks before getting inked: the CDC finds that two Seattle men developed skin infections in 2009, likely caused by a type of bacteria that has not been previously linked to tattooing.
In both men — a 44-year-old and a 35-year-old who visited the same Seattle-area tattoo parlor — the infections were thought to have been caused by Mycobacterium haemophilum, a bacteria that typically affects people with weakened immune systems. But both men who developed infections had perfectly healthy immune systems; their infections did not clear up for several months after they sought treatment.
The culprit may have been the municipal water source used by the tattoo parlor, the CDC study [PDF] finds. “The patrons were thought to have been exposed through use of tap water during rinsing and diluting of inks,” study author Meagan K. Kay told U.S. News and World Report. A follow-up investigation did not find M. haemophilum in water samples or on surfaces in the parlor, but water is considered a reservoir for the bacteria, according to the study.
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Investigators also did not find any infractions of safety or sanitation standards at the Seattle tattoo parlor, but cautioned against the use of municipal water. “Use of tap water during any part of the tattoo procedure should be avoided,” Kay said. “Measures should be taken by tattoo artists to prevent infections, including proper training, use of sterile equipment, and maintaining a clean facility.”
The study authors also note that while the U.S. Food and Drug Administration regulates the inks and pigments used in tattooing, the rules apply only when cosmetics or color additives are involved. Tattooing itself is not considered a sterile procedure and is not federally regulated.
Tattoo artists should take care to keep their practices safe and clean, but there’s a lot consumers can do before getting inked as well. “Shop around, review people’s techniques, and make sure [you] really want to have this done,” said Myrna L. Armstrong, an emeritus professor in the nursing school at Texas Tech University’s Health Sciences Center, who has been studying tattooing for decades. “While I’m not being negative to the industry, I do think that the customer does need to be aware of the situation he or she is getting into.”
The study appears in the September issue of the CDC’s journal Emerging Infectious Diseases.
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Tara Thean is a TIME contributor. Find her on Twitter at @TaraThean. You can also continue the discussion on TIME‘s Facebook page and on Twitter at @TIME.