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Scientists say baby teeth have a value beyond the payouts they get from the tooth fairy. By examining the layers in these teeth, they are discovering how exposure to metals common in the environment can affect both developing babies' brains and behavior in adolescents. NPR's Maria Godoy has more.
MARIA GODOY, BYLINE: Baby teeth, it turns out, are kind of like a historical record of our early life. They start to form in utero, beginning in the second trimester, and they develop layer by layer, bringing in elements from the mother's environment.
MANISH ARORA: So they grow in this incremental manner, just like tree rings do.
GODOY: That's Manish Arora, a professor of environmental medicine at the Icahn School of Medicine at Mount Sinai. By using lasers to decode those layers in baby teeth, he says scientists can figure out what metals in the environment children were exposed to week by week, even before they were born.
ARORA: It seems like an impossible question to answer, but luckily for us, baby teeth are this amazing organ.
GODOY: In a new study in the journal Science Advances, Arora and his colleagues use this technique to examine the baby teeth shed by nearly 500 children in Mexico City. The kids have been followed since their mothers were pregnant. They're now adolescents. The researchers also took detailed behavior assessments of the kids and MRI scans of their brains. Study coauthor Megan Horton says the baby teeth allowed them to figure out the timeline. The brain scans helped them link those exposures to effects.
MEGAN HORTON: Using MRI allows us to look at what those exposures are doing to the brain in terms of its structure, connections and how different areas of the brain communicate.
GODOY: The researchers looked at exposures to nine metals common in the environment, including lead, zinc and copper. Some, like manganese, are essential to growing bodies in trace amounts, but too much can be harmful to developing brains. What they discovered is that it's not just how much of these metals babies are exposed to that matters but when.
HORTON: We found that exposure to this metal mixture during this critical period of around 6 to 9 months of development was strongly associated with negative changes in behavior in these adolescents.
GODOY: Things like increased inattention and hyperactivity - they also found a strong link to changes in overall brain volume and the way different areas of the brain connect with each other. The researchers say the findings underscore the need for environmental regulations that prioritize protecting kids from the start. After all, they say, while we can't change our genes, we can try to change our environments to ensure healthier outcomes for children. Maria Godoy, NPR News.
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