Tattoos really are more than skin deep—and that raises questions about their safety.Many people enjoy the aesthetic beauty of tattoos. But the brightly colored inks that make tattoos so vibrant and striking also carry health concerns, report authors of a new paper related to tattoo safety.According to the Pew Research Center, 45 million Americans have at least one tattoo; roughly $1.65 billion is spent on tattoos each year in the U.S.