Higher Blood Lead Levels Lower IQ

Children living near toxic waste sites may experience higher blood lead levels, resulting in a loss of intelligence quotient (IQ) points.

Children from lower and middle-income countries in Asia who live near such sites may also suffer a higher incidence of mental retardation.

Scientists at the Icahn School of Medicine at Mount Sinai (New York, NY, USA) collaborating with the Blacksmith Institute (New York, NY, USA) measured lead levels in soil and drinking water at 200 toxic waste sites in 31 countries then estimated the blood lead levels in 779,989 children who were potentially exposed to lead from these sites in 2010.

The blood lead levels ranged from 1.5 to 104 µg/dL, with an average of 21 µg/dL in children ages four years and younger. The average blood lead level in an American child is approximately 1.3 µg/dL. These higher blood lead levels could result in an estimated loss of five to eight IQ points per child and an incidence of mild mental retardation in six out of every 1,000 children. The condition of mental retardation is defined as having an IQ below 70.

Kevin Chatham-Stephens, MD, Pediatric Environmental Health Fellow and coauthor of the study, said, “We found an average predicted blood lead level of 21 µg/dL, which is very high. Lead has serious, long-term health consequences such as the potential to impair cognitive development in children and cause mental retardation. We have shown that children who were chronically exposed to toxic waste sites in lower and middle income countries could have had high lead blood levels."

Philip Landrigan, MD, MSc, Dean for Global Health at the Icahn School of Medicine and coauthor of the study, said, “On a global level, this analysis highlights the importance of assigning more public health resources to identify, evaluate and remediate lead-contaminated toxic waste sites in countries like India, Philippines and Indonesia. In order to prevent further detrimental effects on neurodevelopment in children, these countries should create programs to identify toxic wastes and reduce lead exposure." The study was presented on May 6, 2013, at the Pediatric Academic Societies (PAS) annual meeting held in Washington DC (USA).

Related Links:
Icahn School of Medicine at Mount Sinai
Blacksmith Institute