Low Level Lead Exposure Linked to Poor School Performance


Columbia, MD (August 20, 2012) –Today, NCHH released new findings on the impact of low-level lead exposure on school performance. The issue brief, “Childhood Lead Exposure and Educational Outcomes,” summarizes new research connecting small amounts of lead in a child’s blood to problems in school later in life.

In May of this year, the U.S. Centers for Disease Control and Prevention (CDC) updated its guidance on the level of lead in a child’s blood it considers harmful. Children with a blood lead level of 5 micrograms per deciliter (ug/dL) are considered by CDC to have more exposure to lead than 97.5% of their peers. This policy changed CDC’s long-standing guidance, which recommended action at 10 ug/dL.

The NCHH issue brief released today outlines evidence from a growing body of recent studies revealing the strong relationship between slightly elevated blood lead levels in young children and decreased test scores in elementary school and the contribution of childhood lead exposure to the widening achievement gap in the United States.

One of the studies summarized included more than 57,000 children and found that blood lead levels as low as 4 micrograms per deciliter at three years of age increase the likelihood that a child will be classified as learning disabled in elementary school.

Another study of 48,000 children found that children were at least 30% more likely to fail third grade reading and math tests if their blood lead level was over 5 µg/dL. Third grade test scores provide an important school success indicator, since low scores are highly correlated with high school dropout rates.

The evidence shows that children with higher blood lead levels are less likely to place into advanced and intellectually gifted programs. These results hold true even when considering factors such as race, family income, and others that might affect learning-disabled status.

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