A new sunscreen ingredient, bemotrizinol or BEMT, has won approval in the US. | Boston Globe via Getty Images For the first time in the 21st century, the United States has approved a new sunscreen ingredient. Well, new to us. It’s called bemotrizinol, also known as BEMT, and it’s been available in Europe and Asia for years. But the peculiar way that sunscreen is regulated in the United States — as an over-the-counter drug rather than a cosmetic — had long prevented it from coming to American s