A Doctor’s Viewpoint: Lead in Gasoline: A Public Health Success Story

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A Doctor’s Viewpoint: Lead in Gasoline: A Public Health Success Story

Herb Needleman, M.D.

Professor of Pediatrics and Child Psychiatry, University of Pittsburgh

Monday, September 27, 2004

Lead poisoning is a manmade disease. We know where lead is, what it does to children, and how to get rid of it. We know enough to wipe the disease out completely: to take it out of the pediatric textbooks and move it into the history of medical victories. By understanding lead toxicity, we can gain useful insight into the nature and remedy of many other environmental hazards for children.

Childhood lead poisoning was first reported in America in 1914. It was at that time believed that if a poisoned child did not die, he or she was left with no trace of the disease. This was disproved in 1943 with the finding that 19 of 20 children who had recovered from acute poisoning had severe school problems, behavior disorders and impaired cognition. The major sources of lead for children are old paint, dust, water and air.

The removal of lead from gasoline in the United States, begun in the 1970’s and completed by 1991, resulted in dramatic lowering of blood levels. The mean blood lead level in 1975 was 15.5 µg/dl. The mean blood lead level today is less than 2µg/dl, clear testimony to the benefits of sound public health policy.

Although lead was banned from household paint in the 1970’s, many houses inhabited today were built before 1950 and have leaded surfaces. Window sills and frames are particularly rich sources of lead. With time, many of these surfaces chalk and powder, and the lead particles become part of household dust. Approximately 18 million children under 5 years of age are reported to live in houses built before 1950.

The toxic level of lead in blood was defined as 60 µg/dl (60 millionths of a gram in 100 cc of blood) in the 1960’s. With better studies, lead-related deficits were found at lower and lower levels. It currently has been set at 10µg/dl. African American children, and children in poverty are among those at highest risk, but middle class children do not escape. The most recent studies have demonstrated effects on children’s cognition at levels below 10µg/dl.

Children with no visible signs of lead toxicity first were reported to have lower IQ scores in the 1970’s. Since then, over 30 studies of children, conducted around the world have demonstrated deficits in cognition as measured in IQ tests. Three recent studies have shown effects on IQ at blood lead levels below 10µg/dl. This increases the number of children at risk. Four well conducted studies have shown that lead exposure is associated with antisocial behavior and juvenile delinquency.

The removal of lead from gasoline had a dramatic impact on the health of children. The figure below, which shows the close relationship between sales of leaded gasoline and blood lead levels, is strong proof that good public health policy can pay off handsomely. There is still work to be done: Approximately 310,000 children in the United States have blood lead levels greater than 10µg/dl.