An investigation into skin lesions developed by two individuals after getting tattoos has concluded that both were infected with a bacteria not previously linked to the business.

The infections involved Mycobacterium haemophilum, which usually only strikes individuals with compromised immune systems.

In this instance, however, the patients, both from Seattle, developed rashes despite the fact that both had normal immune systems, a report on the investigation found.

The authors pointed out that tattooing is not considered a sterile procedure, is not regulated at the federal level and can be risky. And while the specific inks and colorings (pigments) commonly used to apply tattoos are regulated by the U.S. Food and Drug Administration, the rules usually apply only when cosmetics or color additives are involved.