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Childhood Lead Exposure Can Still Have an Impact Many Years Later

     

The ongoing water crisis in Flint, Mich., has brought concerns over lead poisoning back into the public’s attention, but the problem of lead exposure is not isolated to Flint. According to the Centers for Disease Control and Prevention, at least half a million U.S. children age 1 to 5 have elevated lead levels (above 5 micrograms per deciliter).

At high levels lead can affect nearly every system in the body. It can contribute to learning and behavior problems, slowed growth and development, and hearing and speech problems. Recent studies have associated even very low lead exposure with ADHD.

Lead exposure can come from many sources, including paint, gasoline, solder in pipes and consumer products. People can be exposed through several pathways, including food, water, dust, and soil.

blog-lead-graphic

In the U.S., lead use was phased out of gasoline in the 1970s and mid-1980s. While the use of lead has been limited for many years, children can still be exposed. For example, children can be exposed through soil that absorbed lead from past gasoline use, from paint in older houses and from lead leaching from older pipes, as occurred in Flint. Children’s exposure in the U.S. is primarily through lead paint in older houses or in surrounding soil and dust.

While effects of lead on children’s IQs have been well-established, long-term effects have been less studied. A recent study by researchers at Duke University found that exposure to lead can have a negative impact on children’s lives for decades.

The study followed a group of 1,000 children in New Zealand born in the early 1970s through to midlife. Because of the high lead levels in gasoline at the time in New Zealand, lead exposure among children was widespread and exposure was not related to children’s socioeconomic status. Study participants with higher lead levels in childhood tended to have poorer cognitive function at midlife—they had a decline in IQ at age 38. They also saw lower socioeconomic status compared to their parents.

The researchers suggest that “lead exposure may be one factor curtailing upward social mobility for vulnerable children.” In the U.S., children at greater risk of lead exposure include economically disadvantaged children, children of racial-ethnic minority groups, recent immigrants, and children living in older, poorly maintained rental properties.

Pediatrician John D. Cowden, M.D., M.P.H. commenting on the study in NEJM Journal Watch noted that: “Though these difference in IQ and socioeconomic status are small from the clinical perspective, the cumulative impact of childhood lead exposure could be significant.” He argues that “vigilance, rather than complacency, must define our approach to public health policy and pediatric care.”

More information on lead exposure and children is available from the CDC, Lead: Information for Parents.

References

  • Reuben, A., et al. (2017). Association of Childhood Blood Lead Levels With Cognitive Function and Socioeconomic Status at Age 38 Years and With IQ Change and Socioeconomic Mobility Between Childhood and Adulthood. JAMA 2017;317(12):1244-1251. Also see a documentary film about the study, “Predict My Future: The Science of Us.”
  • Bellinger DC. Childhood lead exposure and adult outcomes. JAMA 2017 Mar 28; 317:1219.
  • Cowden, JC. How did lead exposure affect the children of the ‘70s? NEJM Journal Watch. March 28, 2017.M

     

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