Nearly a third of U.S. adults have tattoos, but how many people know what's really in the ink? Despite new regulations, researchers have found many commercial inks contain unlisted and potentially harmful ingredients. John Swierk, an assistant professor of chemistry at Binghamton University, and his team are trying to figure out exactly what goes into each vial of tattoo ink—and how tattoos actually work—to help make body art safer. Email us at [email protected] if you have any questions, comments or ideas for stories we should cover! Discover something new everyday: subscribe to Scientific American and sign up for our daily newsletter.  Science Quickly is produced by Rachel Feltman, Kelso Harper, Madison Goldberg and Jeff DelViscio. This episode was hosted by Rachel Feltman, with guest John Swierk, assistant professor of chemistry at Binghamton University. Our show is edited by Elah Feder, Alexa Lim, Madison Goldberg and Anaissa Ruiz Tejada, with fact-checking by Shayna Posses and Aaron Shattuck. The theme music was composed by Dominic Smith. Learn more about your ad choices. Visit megaphone.fm/adchoices