Study measures toxic metal levels in children residing in Vietnamese smelting village
March 12, 2014
Recycling car batteries by smelting them into lead ingots may recharge a community’s economy, but a study by researchers at UNC’s Gillings School of Global Public Health indicates that the resulting exposure to toxic metals can affect children who live near the smelters.
The research team included Jonathan Kotch, MD, MPH, professor, and Viet Nguyen, MD, project coordinator, of the Gillings School’s Department of Maternal and Child Health, and Rebecca Fry, PhD, of the Department of Environmental Sciences and Engineering. Together, they conducted a pilot study of 20 children in a smelting village in Vietnam, measuring their whole blood lead levels (BLLs) and levels of arsenic, cadmium, chromium, lead, manganese and mercury in toenails.
The research findings were published online Feb. 4 in BioMed Central Public Health.
Every child tested had BLLs that exceeded the maximum level deemed safe by the U.S. Centers for Disease Control and Prevention, and the BLLs of 25 percent of the children reached the level of recommended medical intervention. Similarly, all children had detectable levels of arsenic, cadmium, chromium, lead, manganese and mercury. On average, the children’s levels of lead, manganese and mercury were well above levels previously reported in children. The closer the children lived to a smelter, the higher their levels of metal toxicity. The research showed that reducing the distance to the nearest active smelter by half increased BLL by 116 percent.
Widespread environmental lead exposure contributes to detrimental neurodevelopmental effects in children. The consequences include decreased IQ and cognitive functioning, and diminished attention span, academic proficiency, fine-motor control and visual-motor control. Previous studies have shown a connection between these adverse neurodevelopmental outcomes and substantial economic losses, estimated to be as much as $319 billion annually in the U.S.
Children are particularly susceptible to lead poisoning because they are more likely to put their hands in their mouths and they have higher gastrointestinal absorption of lead.
Lead exposure often coincides with other toxic metal exposures, due to co-contamination of air, soil or water supplies by industrial activities. Co-exposure to toxic metals can lead to birth defects and cancer. Combined exposure to arsenic, cadmium, mercury and lead can increase the toxic effects compared to exposure to a single metal.
The significant potential for harm to children’s health prompted the UNC researchers to collaborate, building upon their established research programs supported by the National Institute of Environmental Health Sciences. Kotch and Fry designed the study. Nguyen traveled to Nghia Lo, a smelting village about 15 miles southeast of Hanoi in Vietnam’s Red River Delta, to collect the data in 2011. The children tested ranged in age from 18 months to 5 years old. The data were analyzed by environmental sciences and engineering students Allison Sanders and Sloane Miller. For children whose BLLs reached the level of recommended medical intervention, the researchers offered chelation treatment at the study’s expense.
The study results revealed that children in the study area are not adequately protected from exposure to toxic metals. The research emphasizes the need for both increased biomonitoring of metal exposure and public health strategies in these communities to alleviate toxic exposure in children.