An assessment of more than 20,000 wells nationwide by the U.S. Geological Survey shows 25 states with a high prevalence of corrosivity in untreated groundwater, most of them located in the Northeast, Southeast and Pacific Northwest.

Prevalence of corrosivity in groundwater creates a high risk for lead leaching in homes serviced by untreated private water sources, such as wells, springs and cisterns. “Corrosive groundwater, if untreated, can dissolve lead and other metals from pipes and plumbing fixtures,” the USGS report concluded.

But the July 13 report also said that “additional work would be needed to better understand the relations between potential corrosivity of groundwater and the occurrence of lead.”

Some states with the highest prevalence of potentially corrosive groundwater in the South include Mississippi, Georgia and South Carolina. In the Northeast, Maine, New Hampshire, Massachusetts, Connecticut, Rhode Island, New Jersey and Maryland ranked among the highest.

Lead states

Pennsylvania tops the list of states with the highest rate of blood lead levels in children, based on an analysis of CDC state surveillance data by Bloomberg BNA.

More than 2 percent of children tested showed elevated blood levels in Pennsylvania over the last 11 years. Illinois was a close second, with Rhode Island, Ohio and Maine following behind.

The Centers for Disease Control and Prevention (CDC) does not list a safe level of blood lead levels and warns that childhood exposure to lead can lead to brain damage as well as learning, hearing and speech problems. Bloomberg BNA's Llewellyn Hinkes-Jones has the full story at USGS Water Well Study Finds 25 States at Risk for Lead.

Below is an interactive map from Bloomberg BNA on the CDC's childhood lead poisoning data.