Water quality has been on many Americans' minds this year as we've watched the residents of Flint, Michigan, struggle with elevated lead levels in their tap water. And it's not just Flint. A recent investigation by USA Today found elevated lead levels in 2,000 water systems serving six million Americans. Exposure to lead harms kids' developing brains, putting them at risk for behavioral problems and learning disabilities. The Centers for Disease Control and Prevention (CDC) says there is no safe level of lead exposure for babies and children. In adults, lead can raise the risk for heart disease.
Flint's troubles have brought back into the news a problem that, for a little while, America apparently forgot. "Until about 1985 water was generally acknowledged as potentially a significant source of lead exposure," Environmental Health Perspectives reported in 2010. Then, researchers discovered that American kids often get lead into their bodies through ingesting chips of leaded house paint and dust. These findings may have shifted many public-health leaders' focus from water to paint, leaving "the majority public health opinion ... largely blind to water as a source of lead to children."
Cases of lead poisoning from tap water cropped up even as the focus remained on paint. In separate cases, officials found tap water had poisoned two children in North Carolina, Environmental Health Perspectives reported in 2009. After one public housing development in Maine changed its water treatment system, 15 adults and children—out of 36 people who officials tested—were found to have elevated levels of lead in their blood. In the early 2000s, Washington, D.C., suffered from widespread lead contamination in its tap water.
To be sure, paint is an important source of lead poisoning in American children. One recent estimate found that, for every $1 America spends on controlling the dangers of lead house paint, the economy gains $17 to $221 through saved costs on doctor's visits, special education classes, and criminal justice; low-level lead poisoning causes behavioral problems in kids, some theorize, which can turn into criminal behavior once they are teenagers and adults. But it's clear that tap water can still be a major problem.
As Mary Jean Brown, chief of lead poisoning prevention at the CDC, told Environmental Health Perspectives in 2010: "It would be a mistake to place various sources of lead in competition with each other. Identifying and removing sources of lead before children are exposed should be our focus."