Elements found in primary teeth correlate with autism spectrum disorder

Rockville, Md. — Primary teeth from children with autism spectrum disorders contain less of the essential nutrients zinc and manganese and more of the neurotoxin lead compared to those from children without ASD, according to a new study published June 1 in the journal Nature Communications. 

In the study, researchers from the Icahn School of Medicine at Mount Sinai in New York and the Karolinska Institutet in Sweden used tooth biomarkers to analyze primary teeth collected from 32 pairs of twins and 12 individual twins enrolled in the Roots of Autism and Attention Deficit Hyperactivity Disorder Twin Study in Sweden, according to a Mount Sinainews release.

“The differences in metal uptake between children with and without [ASD] were especially notable during the months just before and after the children were born,” according to the National Institute of Environmental Health Sciences, part of the National Institutes of Health, which funded the study. 

NIEHS said the scientists determined this by “using lasers to map the growth rings in baby teeth generated during different developmental periods.”

“We found significant divergences in metal uptake between ASD-affected children and their healthy siblings, but only during discrete developmental periods,” said Dr. Manish Arora, Ph.D., an environmental scientist and dentist at Mount Sinai. “Specifically, the siblings with ASD had higher uptake of the neurotoxin lead, and reduced uptake of the essential elements manganese and zinc, during late pregnancy and the first few months after birth, as evidenced through analysis of their baby teeth. Furthermore, metal levels at three months after birth were shown to be predictive of the severity of ASD eight to ten years later in life.” 

NIEHS said researchers also observed lower uptake of manganese in children with ASD, both before and after birth; children with ASD also had lower zinc levels earlier in the womb, but the levels then increased after birth, compared to children without ASD.

NIEHS noted that prior studies relating toxic metals and essential nutrients to autism have faced “key limitations, such as estimating exposure based on blood levels after autism diagnosis rather than before, or not being able to control for differences that could be due to genetic factors.”

“A lot of studies have compared current lead levels in kids that are already diagnosed,” said Cindy Lawler, Ph.D., head of the NIEHS Genes, Environment and Health Branch. “Being able to measure something the children were exposed to long before diagnosis is a major advantage.”

The researchers noted that larger studies are needed to confirm the connection between metal exposure and uptake and ASD.