The trouble with trying to solve the country’s lead problem is that all the easy fixes have already been done. “Yes, if we could replace all of our 100-year-old water mains overnight, we’d gladly do it,” says Gary Burlingame of the Philadelphia water department. But such projects can carry a steep political and economic price tag. Here’s what it would cost to put a dent in the lead exposure of American kids:
To make all U.S. pipe replacements deemed “urgent” by the American Society of Civil Engineers
To perform lead-paint abatement on the 24 million at-risk homes, at an average cost of $9,000 per home
To treat the estimated 535,000 children with injurious levels of lead in their blood
To test the soil in the 13,500 playgrounds in the 100 largest U.S. cities
A version of this article appears in the March 1, 2016 issue of Fortune.