Understanding what the lead levels in Pa.’s kids mean

The potential public health crisis linked to high levels of lead in the water of Flint, Mich. has raised concerns - some justified, some misguided - that lead-poisoning crises could be affecting our own communities.

Earlier this month, news media including the Philadelphia Inquirer and the online magazine Vox bore out this fear by highlighting statistics gathered for the 2014 Childhood Lead Surveillance Report from the Pennsylvania Department of Health. It showed that many cities in the state, including Philadelphia, actually have a higher percentage of children with lead exposure than Flint. What it seemed to say is quite alarming, but, in my opinion, an overblown alarm.

An appropriate historical perspective is necessary to properly understand what the 2014 report findings actually mean. The current blood levels of lead in Pennsylvania would have been ignored when I started practicing pediatrics 37 years ago. Since then, the decrease of lead poisoning in children on a local and national level has been considered a public health triumph.

I am not saying that lead in our water and in our children is not dangerous or that we should not continue efforts to lower it. The Center for Disease Control and Prevention states that "there is no known safe level of lead in our blood." Once a person ingests lead, it stays in their bones forever. Elevated lead in children is essentially not treatable except by removing the source of lead so it does not get worse. Trying to use a medicine called a "chelating agent" to remove lead actually mobilizes the lead from the bones and can make the child more ill.

In 1971, blood lead levels were considered dangerous if above 40 micrograms per deciliter, which is a very small amount; the average among American children then was about 20. In 1976, the CDC declared the level of  concern was 30, because data showed children with levels that high were having trouble in school. One of the three major sources of lead in our environment, lead paint, was banned in the US in 1978, and average blood lead levels fell a little.

In 1985, the CDC lowered the "blood level of concern" to 25 and to 10 in 1991. These changes were based on research showing that children suffered intellectually at those levels. Joel Schwarz, now a professor of environmental epidemiology at Harvard, did seminal work on leaded gasoline and its effect on children that prompted the 1996 national ban of the tetraethyl lead gasoline additive.

"For every microgram of lead above 10 in a child's blood that child loses one point on their IQ forever," he told me in 1991.

In 2012, unable to pinpoint the still lower level that could cause harm, the CDC dropped its longstanding blood level "of concern" terminology and replaced it with a percentile. Children testing in the top 2.5 percent nationally — currently those with blood lead levels of 5 or more micrograms per deciliter — are now reported to parents and doctors.

Lead in gasoline is a thing of the past in the U.S and lead paint hasn't been sold legally in 38 years. Lead in water pipes still exists under our streets and in older homes.

Overall, the U.S. has done a really great job clearing lead in spite of our politicians and civil servants not, as in Flint, consistently doing their jobs. The heroes of lead clearance in Philadelphia are a group of health department workers called sanitarians who have gone into the poorest corners of this city for over 50 years to clean up lead and other health hazards, often while not getting much government support.

Current lead levels found in American children are the lowest since measurement began after World War II. Even so, the U.S. needs to do more to eliminate lead where it persists, frequently in our poorest neighborhoods, in order to protect out children.

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