(Relaxnews)—"It is especially important for consumers to be aware of the potential risks, report any problem that develops to the tattoo artist and see a board-certified dermatologist for proper diagnosis and treatment," says Dr. Michi Shinohara, a clinical assistant professor of dermatology at the University of Washington in Seattle. In recent studies, a chemical in black inks called benzo(a)pyrene has caused skin cancer in lab animals, and malignant melanomas have been discovered in some tattoos. Many unknowns exist about how these new tattoo inks interact with the skin and within the body, Shinohara warns. While allergic reactions to tattoo pigments are the most common problem, she warns that bacterial infections as well as syphilis and hepatitis B and C have been associated with non-sterile tattooing practices. Before getting inked, here is Shinohara's advice on playing it safe: • Be sure your tattoo artist is licensed according to your country's or state's requirements, and only go to a professional tattoo parlor. Make sure all needles are removed from a sterile single-use package before use, and that your artist washes his or her hands and wears sterile gloves. • If a problem lasts more than one to two weeks, see a dermatologist. • If you suffer from a chronic skin condition such as psoriasis, eczema, or a tendency toward keloid scarring, talk with a dermatologist before getting a tattoo. • Never get a tattoo over an existing mole because a tattoo can hide any changes or problems that may occur within the mole over time.