WASHINGTON — In one city after another, the tests showed startling numbers of children with unsafe blood lead levels: Poughkeepsie and Syracuse and Buffalo. Erie and Reading. Cleveland and Cincinnati.

In those cities and others around the country, 14 percent of kids — and in some cases more — have troubling amounts of the toxic metal in their blood, according to research published Wednesday. The findings underscore how many US children still live in environments where they’re likely to encounter lead.

‘‘We’ve been making progress for decades, but we have a ways to go,’’ said Harvey Kaufman, senior medical director at Quest Diagnostics and a co-author of the study, which was published in the Journal of Pediatrics.

Kaufman and two colleagues at Quest examined more than 5.2 million blood tests for infants and children under age 6 that were taken between 2009 and 2015.

The researchers found that while blood lead levels declined nationally overall during that period, roughly 3 percent of children across the country had levels that exceed 5 micrograms per deciliter — the threshold that the Centers for Disease Control and Prevention considers cause for concern. in some places, those figures are much higher.

In certain regions of the country, including parts of New York, Pennsylvania, and Ohio, more than 1 in 7 children tested for elevated levels of lead in their blood. Minnesota had the highest overall rate of young children with disturbing blood lead levels, at 10.3 percent.

The news wasn’t entirely bad. States such as California and Florida had the lowest rates of elevated blood lead levels in children, at 1.4 percent and 1.1. percent, respectively. And over the six years included in the study, New Hampshire saw the largest absolute decline in high blood lead levels, from 9.7 percent to 2.6 percent.

Washington Post