REGRET—THAT’S WHAT MANY PEOPLE WITH TATTOOS eventually feel about their body art. Yet the only recourse is a series of laser treatments that leave scars. Doing nothing is not appealing either: Inks include carcinogens such as industrial-grade carbon black and compounds found in auto-body paint. For those whose body art is still on the drawing board, Rox Anderson, director of the Wellman Center for Photomedicine at the Massachusetts General Hospital, has invented bio-resorbable ink encased in polymer beads that burst and disappear after a single treatment.