CLEVELAND — One hundred fifty miles northwest of here, the residents of Flint, Mich., are still reeling from the drinking water debacle that more than doubled the share of children with elevated levels of lead in their blood — to a peak, in mid-2014, of 7 percent of all children tested.

Clevelanders can only sympathize. The comparable number here is 14.2 percent.

The poisoning of Flint’s children outraged the nation. But too much lead in children’s blood has long been an everyday fact in Cleveland and scores of other cities — not because of bungled decisions about drinking water, but largely because a decades-long attack on lead in household paint has faltered. It is a tragic reminder that one of the great public health crusades of the 20th century remains unfinished.

“Unless there is some sort of concerted national effort to do something about this problem, it’s going to persist for years to come,” said Philip J. Landrigan, a leading expert on lead and professor of preventive medicine and pediatrics at the Mount Sinai School of Medicine.

“Lead is a big problem in this country, and it frustrates me to no end that except in rare cases, it passes unnoticed.”