Dental Tribune International

Researchers detect lead contamination in children’s primary teeth

LOS ANGELES, U.S.: Researchers have recently examined shed primary teeth of children living near the Exide Technologies plant in Verona, California. Two chemical elements, namely airborne lead and arsenic from recycled car batteries, were identified in the children’s teeth as a result of soil contamination. The research team believes that looking at lead in teeth could be an effective technique to detect and subsequently reduce industrial lead exposure in children.

“We found the higher the level of lead in the soil, the higher the amount of lead in baby teeth,” said lead author Dr. Jill Johnston, Assistant Professor of Preventive Medicine at the Keck School of Medicine of the University of Southern California (USC). “There’s no safe level of lead; it’s a potent neurotoxin. Our study provides insight into the legacy of the impact of industrial contamination on children.”

For the study, researchers from USC collected 50 primary teeth from 43 children in five communities: Boyle Heights, Maywood, East Los Angeles, Commerce and Huntington Park. Using laser ablation and inductively coupled plasma mass spectrometry, an analytical technique for molecular-level information, the researchers were able to look at the teeth layer by layer and assign time points for lead contamination. They also measured lead and arsenic in the dentine and could identify lead contamination acquired during the baby’s first year, when infants are at higher risk of exposure.

The tooth findings were then matched with soil contamination data gathered from the California Department of Toxic Substances Control, which had collected 117,356 samples from the upper layers of soil on nearly 8,000 properties. The researchers found that the median concentration of lead in soil was 190 ppm, well above California’s threshold of 80 ppm. In total, 14 percent of soil samples exceeded 400 ppm. Communities with the highest lead levels in the soil also had the highest lead levels in children’s teeth. Of the five communities, Boyle Heights and East Los Angeles showed the highest contamination levels in teeth, followed by Maywood, Huntington Park and Commerce, respectively. According to the researchers, the higher levels in Boyle Heights and East Los Angeles could be a result of prevailing winds. In some cases, higher exposure occurred while the baby was still in the womb, meaning that the mother’s exposure to lead was transmitted to her unborn child.

The researchers are of the opinion that measuring lead in shed baby teeth is a promising technique to assess prenatal and early life exposure, since it reflects past exposures and, therefore, could be an important indicator of harm. “Higher lead in teeth means higher lead in the brain, kidney and bones,” Johnston said. “Testing women for lead during pregnancy, or even earlier, as they enter child-bearing age, may be needed to decrease lead exposure to their future offspring.”

The study, titled “Lead and arsenic in shed deciduous teeth of children living near a lead-acid battery smelter,” was published on May 6, 2019, in Environmental Science and Technology ahead of inclusion in an issue.

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