Kearsley Reservoir 475 FLINT Flint R. 69 1 MILE Bishop International Airport Where lead in water sample exceeded 15 parts per billion Kearsley Reservoir 475 FLINT 69 Flint R. 1 MILE Bishop International Airport Where lead in water sample exceeded 15 parts per billion 475 FLINT 69 Flint R. 1 MILE Where lead in water sample exceeded 15 parts per billion

Some of these samples were taken in testing conducted by the city or state from July 2014 to January 2016. Other samples were analyzed by researchers at Virginia Tech beginning in August 2015. More than 90 of the homes on the map had lead levels higher than 100 parts per billion.

One of the largest concerns is that many Flint children were found to have high levels of lead in their blood. The city has more than 8,000 children under age 6, a group that is particularly vulnerable to the effects of lead poisoning, because it affects brain development.

Even small amounts of lead can cause lasting health and developmental problems. Lead should not be detectable in the body, according to Brenda Eskenazi, a professor of public health at the University of California, Berkeley. Lead poisoning causes “poorer cognition, attention disorders and, at higher doses, seizures, coma and death,” Dr. Eskenazi said.

The highest lead levels were in older neighborhoods.

Some of the highest levels of lead were found in the oldest parts of town, with homes built before 1940. “Homes of that era are more likely to have lead service-line pipes,” said Marc Edwards, a Virginia Tech professor directing the sampling effort. Many cities stopped installing them in the 1930s.

Kearsley Reservoir 475 FLINT Flint R. 69 1 MILE Bishop International Airport Buildings built in 1940 or earlier Kearsley Reservoir 475 FLINT 69 Flint R. 1 MILE Bishop International Airport Buildings built in 1940 or earlier 475 FLINT 69 Flint R. 1 MILE Buildings built in 1940 or earlier

There are 15,000 to 25,000 lead service lines in Flint, but it is unclear exactly where they are. A team at the University of Michigan–Flint is working to map their locations.