Kristi Tanner

Detroit Free Press

Corrections and clarifications: This article has been updated to clarify the health experts recommend that all of Flint’s children be treated as though they have been exposed to lead.

FLINT, Mich. — In order to address the public health crisis in Flint, every Flint child under 6 years of age -- 8,657 children, based on an analysis of Census data -- should be considered exposed to lead.

The direction came earlier this week from the doctor who forced the state to acknowledge Flint’s lead problem and the state itself.

The exposure began in April 2014 after the city switched from using Detroit’s water system, which pumps water out of Lake Huron, to its own treatment plant, which drew water from the Flint River.

In recommendations to the state on Monday, Dr. Mona Hanna-Attisha said all kids under the age of 6 should be treated with some kind of prevention actions.

Eden Wells, the state's chief medical executive, reiterated in a news conference Monday the fact that all children who drank the city's water since April 2014 have been exposed to lead. "It is important when we think about a public health perspective that we consider the whole cohort ... exposed to the drinking water, especially 6 years and under since April 2014, as exposed, regardless of what their blood level is on Jan. 11."

The state's most recent report, based on tests conducted between October and December 2015, shows that 43 people — only a small portion of the number exposed — had elevated blood lead levels. That's because these tests measure only the amount of lead in a person's blood, which decreases after about 30 days, according to the U.S. Centers for Disease Control and Prevention.

That means testing done today does not represent past exposure. Once lead is present in the bloodstream, it is distributed throughout the body, primarily to bones, teeth and soft tissue. Lead accumulates in the body over time. Blood-lead tests used to identify recent or ongoing exposure to lead, do not measure the overall lead burden in the body.

There is no safe level of lead in the body, but the impacts of lead are considered most severe on the developing brains and nervous systems of children and fetuses. And even the 8,657 Flint children younger than 6 exposed to lead may be a low estimate; It doesn't include unborn children whose mothers drank tainted water during their pregnancies, or children and pregnant women who reside outside Flint but were exposed while visiting relatives, childcare centers or hospitals inside city limits.

See a map of the number of Flint children less than six years of age by block group.

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