Residents of Flint, Michigan, aren’t the only ones who’ve fallen victim to the harmful effects of lead. Across America, 4 million households with kids are exposed to high levels of the toxic element, which can be found in old paint and pipes. In the video below, Gross Science’s Anna Rothschild explains why lead is so dangerous for the developing brain, and how scientists hope to someday mitigate the condition for those who've already been affected.