Years after the Flint water crisis drew national attention, another water pollution issue has emerged in House races in Michigan. Residents are growing concerned about human exposure to so-called forever chemicals, known as perfluoroalkyl or polyfluoroalkyl substances, or PFAS. The chemicals, linked to health problems such as hypertension in pregnant women and a higher risk of developing certain cancers, have been found in groundwater and drinking water systems across the state.Along with other water-centric issues springing up through the summer, including an outbreak of lead contamination in Detroit public school drinking water systems, the current of bad news about Michiganders’ water has made the issue a “powder keg” in the election, said Bob Allison, deputy director of the Michigan League of Conservation Voters.