Local philanthropic groups have set up a charitable fund with the goal of improving health outcomes for children exposed to lead, including through Dr. Hanna-Attisha’s project, the Pediatric Public Health Initiative. Psychologists, nutritionists and child development experts are among the participants in the project, which Hurley is overseeing with Michigan State University’s College of Human Medicine, where Dr. Hanna-Attisha is an assistant professor of pediatrics.

“We have a unique opportunity to build a model public health program here,” Dr. Hanna-Attisha said. “We have to throw every single evidence-based resource at these kids, starting now.”

It is impossible to gauge how each child will be affected, partly because the developmental effects of lead poisoning may take years to emerge. A flurry of lead testing has taken place since October, when the Genessee County Health Department finally declared a public health emergency. The agency told residents to stop drinking the water, which was coming from the Flint River, rather than Lake Huron, in an attempt to save money.

Experts say the testing may provide false reassurance. Most residents have probably switched to drinking bottled water, and since lead can be detected in the blood for only about a month, test results may not reflect the extent of their exposure.

“Our kids are already rattled by every kind of toxic stress you can think of,” Dr. Hanna-Attisha said. “Every single day in our clinic we have a 40 percent no-show rate, and it’s not because parents don’t love their children.”

She emphasized, however, that not every child exposed to lead would suffer ill effects. Kim Dietrich, a professor of environmental health at the University of Cincinnati College of Medicine, said that based partly on the blood lead levels of children in Dr. Hanna-Attisha’s study, he did not think serious long-term health problems would be widespread.

About 57 percent of Flint’s 99,000 residents are black, and 40 percent live in poverty, one of the highest rates in the nation for a city its size. Bilal Tawwab, the superintendent of the city school system, said that one school nurse serves the 5,400 students in the district, but that he hoped some of the money flowing into Flint might help open health centers in every school.