NEW YORK, New York, May 7, 2013 (ENS) – Children living near toxic waste sites in India, Indonesia and the Philippines may absorb high levels of lead into their blood, diminishing their intelligence and raising their risk of mental retardation, new research finds.
Scientists from Mount Sinai Medical Center 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.
The results were presented Monday at the Pediatric Academic Societies annual meeting in Washington, DC by author Kevin Chatham-Stephens, MD, a pediatric environmental health fellow with the Icahn School of Medicine at Mount Sinai Medical Center in New York.
The researchers found that blood lead levels in the children they studied ranged from 1.5 to 104 micrograms of lead per deciliter of blood (µg/dL), with an average of 21 µg/dL in children ages four years and younger.
Dr. Chatham-Stephens said these higher blood lead levels could result in a 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 average blood lead level in an American child is approximately 1.3 µg/dL,” said Dr. Chatham-Stephens. “Our research 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,” said Chatham-Stephens. Mental retardation is defined as having an IQ below 70.
“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 these countries,” said co-author Philip Landrigan, MD, MSc, dean for global health at the Icahn School of Medicine at Mount Sinai.
“In order to prevent further detrimental effects on neurodevelopment in children, these countries should create programs to identify toxic wastes and reduce lead exposure,” said Dr. Landrigan.
“This study is important because, to our knowledge, the burden of disease from these toxic waste sites has never been calculated before,” said Dr. Chatham-Stephens. “We are showing that children who were chronically exposed to toxic waste sites in lower and middle income countries could have had high lead blood levels.”
Titled, “The Pediatric Burden of Disease from Lead Exposure at Toxic Waste Sites in Low and Middle Income Countries in 2010,” the study was a joint research partnership between Mount Sinai and the Blacksmith Institute. It was published online Monday in the journal “Environmental Health Perspectives.”
“Our research shows that chemical pollutants from toxic waste sites are insufficiently studied in lower and middle income countries and that disease and death caused by these chemicals can contribute to loss of life,” said Dr. Chatham-Stephens.
In another conclusion from the same study, Dr. Chatham-Stephens and his colleagues found that 373 of the toxic waste sites with elevated levels of lead and chromium caused a high number of “healthy years of life lost” in people living nearby.
“Lead and hexavalent chromium proved to be the most toxic chemicals and caused the majority of disease, disability and mortality among the individuals living near the sites,” said Dr. Chatham-Stephens.
Eight chemicals were sampled and collected at the toxic waste sites in 2010. The samples were measured for pollutant levels in the soil and water and then compared with the 8,629,750 individuals who were at risk of exposure around these sites in order to calculate the loss of years of equivalent full health.
In this study, the total number of lost years of full health was 828,722.
In comparison, malaria in the same countries caused 725,000 lost years of full health, while outdoor air pollution caused 1.4 million lost years of full health in 2008, said Dr. Chatham-Stephens.
“This study highlights a major and previously under-recognized global health problem in lower and middle income countries,” said Dr. Landrigan. “The next step is targeting interventions such as cleaning up the sites and minimizing the exposure of humans in each of these countries where toxic chemicals are greatly present.”
Children and women of child-bearing age made up two-thirds of the population studied. “If a woman is pregnant, the fetus may be exposed to these toxic chemicals,” said Dr. Chatham-Stephens. “This data is relevant because the prenatal to early childhood period is the time when individuals are very vulnerable to some toxic exposures, such as lead’s impact on the developing nervous system.”
Lead can cause neurological, gastrointestinal and cardiovascular damage, previous studies have shown, while those also exposed to high levels of chromium have a greater chance of developing lung cancer than people not exposed to these chemicals.