The water crisis gripping Flint, Michigan has exposed thousands of the city’s residents to dangerous lead levels. But Flint is hardly unique. Many other American cities have faced lead contamination in water supplies, and an expanding list of common substances, including some pesticides and flame retardants, may also be linked to significant developmental and neurological problems. Get the latest on this largely hidden crisis at a live forum from the Harvard T.H. Chan School of Public Health, PRI’s The World and WGBH.