David Shiffman is a marine biologist specializing in the ecology and conservation of sharks. He received his Ph.D. in environmental science and policy from the University of Miami. Follow him on Twitter, where he's always happy to answer any questions anyone has about sharks.
The United States bears its share of responsibility for this crisis that is destroying Ukraine and placing the world in "unprecedented danger," as the Bulletin of the Atomic Scientists' new Doomsday Clock statement calls it.
Per- and polyfluoroalkyl substances are a growing concern because of the many health impacts associated with exposure and their tendency to persist in the human body for months to years and in the environment for thousands of years.