Baby Teeth Metals Linked to Autism Risk in NIH Study
Author: NIH/National Institute of Environmental Health Sciences
Published: 2 Jun 2017 - Updated: 18 Aug 2026
Publication Details: Peer-Reviewed | Research, Study, Analysis
Table of Contents:
Synopsis - Definition - Overview - FAQs - Insights, Updates - Related Content
Synopsis
This study, published in Nature Communications and funded by the National Institute of Environmental Health Sciences (NIEHS), examines the relationship between metal exposure and autism by analyzing baby teeth from children with and without autism. Researchers found that children with autism had higher levels of toxic lead and lower levels of essential nutrients like zinc and manganese, especially during critical developmental periods before and after birth. By using lasers to analyze precise layers of dentine, the study offers a novel approach to understanding how early-life metal exposure may contribute to autism risk. These findings are particularly relevant for individuals with disabilities and their families, as they highlight potential environmental factors influencing autism, which could inform future prevention and intervention strategies.*
At a Glance
- 1 - The research appeared in the journal Nature Communications on June 1.
- 2 - Lasers mapped the growth rings in dentine to date each period of metal exposure.
- 3 - Patterns were drawn from 32 pairs of twins and 12 individual twins, with the biggest gaps in pairs where only one sibling had autism.
- 4 - The same baby-teeth method may help study other conditions, such as attention deficit hyperactivity disorder, and researchers say larger studies are needed to confirm the link.
Topic Definition
- Fetal and Postnatal Metal Dysregulation
Fetal and postnatal metal dysregulation refers to the way a developing child's body takes in, distributes, and processes metals such as lead, zinc, and manganese during the months before and after birth. Rather than measuring only how much of a metal a child was exposed to, the concept focuses on the body's changing response to that exposure across specific developmental windows. Scientists can now read this record in naturally shed baby teeth, because the layers of dentine laid down over time preserve a timeline of both toxic metals like lead and essential nutrients like zinc and manganese. Studying these patterns helps researchers explore how early environmental factors, alongside genetics, may shape the risk of conditions such as autism.
Overview
Baby teeth from children with autism contain more toxic lead and less of the essential nutrients zinc and manganese, compared to teeth from children without autism, according to an innovative study funded by the National Institute of Environmental Health Sciences (NIEHS), part of the National Institutes of Health.
The researchers studied twins to control genetic influences and focus on possible environmental contributors to the disease. The findings, published June 1 in the journal Nature Communications, suggest that differences in early-life exposure to metals, or more importantly how a child's body processes them, may affect the risk of autism.
The differences in metal uptake between children with and without autism were especially notable during the months just before and after the children were born. The scientists determined this by using lasers to map the growth rings in baby teeth generated during different developmental periods.
The researchers observed higher levels of lead in children with autism throughout development, with the greatest disparity observed during the period following birth. They also observed lower uptake of manganese in children with autism, both before and after birth. The pattern was more complex for zinc. Children with autism had lower zinc levels earlier in the womb, but these levels then increased after birth, compared to children without autism.
The researchers note that replication in larger studies is needed to confirm the connection between metal uptake and autism.
"We think autism begins very early, most likely in the womb, and research suggests that our environment can increase a child's risk. But by the time children are diagnosed at age 3 or 4, it's hard to go back and know what the moms were exposed to," said Cindy Lawler, Ph.D., head of the NIEHS Genes, Environment, and Health Branch. "With baby teeth, we can actually do that."
Patterns of metal uptake were compared using teeth from 32 pairs of twins and 12 individual twins. The researchers compared patterns in twins where only one had autism, as well as in twins where both or neither had autism. Smaller differences in the patterns of metal uptake occurred when both twins had autism. Larger differences occurred in twins where only one sibling had autism.
The findings build on prior research showing that exposure to toxic metals, such as lead, and deficiencies of essential nutrients, like manganese, may harm brain development while in the womb or during early childhood. Although manganese is an essential nutrient, it can also be toxic at high doses. Exposure to both lead and high levels of manganese has been associated with autism traits and severity.
The study was led by Manish Arora, Ph.D., an environmental scientist and dentist at the Icahn School of Medicine at Mount Sinai in New York. With support from NIEHS, Arora and colleagues had previously developed a method that used naturally shed baby teeth to measure children's exposure to lead and other metals while in the womb and during early childhood. The researchers use lasers to extract precise layers of dentine, the hard substance beneath tooth enamel, for metal analysis. The team previously showed that the amount of lead in different layers of dentine corresponds to lead exposure during different developmental periods.
Arora said that autism is a condition where both genes and environment play a role, but figuring out which environmental exposures may increase risk has been difficult.
"What is needed is a window into our fetal life," he said. "Unlike genes, our environment is constantly changing, and our body's response to environmental stressors not only depends on just how much we were exposed to, but at what age we experienced that exposure."
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 Lawler. "Being able to measure something the children were exposed to long before diagnosis is a major advantage."
The method of using baby teeth to measure past exposure to metals also holds promise for other disorders, such as attention deficit hyperactivity disorder.
"There is growing excitement about the potential of baby teeth as a rich record of a child's early life exposure to both helpful and harmful factors in the environment," said David Balshaw, Ph.D., head of the NIEHS Exposure, Response, and Technology Branch, which supported the development of the tooth method.
Grant Numbers: DP2ES025453, R00ES019597, P30ES023515 (NIEHS); HD073978 (NICHD); MH097849 (NIMH). Reference: Arora M, Reichenberg A, Willfors C, Austin C, Gennings C, Berggren S, Lichtenstein P, Anckarsater H, Tammimies K, Bolte S. 2017. Fetal and postnatal metal dysregulation in autism.
Frequently Asked Questions
NOTE: Researched FAQs by Disabled World (DW)
What are baby teeth made of that lets scientists measure past metal exposure
Baby teeth contain dentine, a hard layer beneath the enamel that forms in growth rings over time, so each layer preserves a record of the metals a child took in during a specific developmental stage.
Why did the researchers study twins for this project
Studying twins let the team control for genetic influences so they could focus on environmental contributors, comparing pairs where one, both, or neither sibling had autism.
What role does manganese play in early development
Manganese is an essential nutrient needed for healthy brain development, but it can also be toxic at high doses, so both too little and too much may affect risk.
Does this study prove that metals cause autism
No, the study shows an association between metal uptake patterns and autism, and the researchers stress that replication in larger studies is needed before any causal conclusion can be drawn.
What is dentine and where is it located in the tooth
Dentine is the hard substance that sits directly beneath tooth enamel and makes up the bulk of the tooth, forming in layers that scientists analyze with lasers.
Why is measuring exposure before diagnosis important
Autism is usually diagnosed at age three or four, so measuring exposure that happened much earlier gives a clearer picture of early-life conditions than blood tests taken after diagnosis.
Which institutions led and funded the research
The work was funded by the National Institute of Environmental Health Sciences, part of the National Institutes of Health, and led by researchers at the Icahn School of Medicine at Mount Sinai.
Can the baby teeth method be used for other conditions
Yes, researchers believe the method holds promise for studying other disorders, including attention deficit hyperactivity disorder, by reading early-life exposure to helpful and harmful factors.
Insights, Analysis, and Developments
Editorial Note: This research underscores the importance of environmental influences in the development of autism, suggesting that early exposure to certain metals may play a significant role. While genetics are known to contribute to autism, this study highlights the need to consider environmental factors as well. Further research in this area could lead to more comprehensive strategies for prevention and treatment, benefiting not only individuals with autism but also their families and caregivers.*
Attribution/Source(s): This peer reviewed publication was selected for publishing by the editors of Disabled World (DW) due to its relevance to the disability community. Originally authored by NIH/National Institute of Environmental Health Sciences and published on 2 Jun 2017, this content may have been edited for style, clarity, or brevity.
* Editorial additions by Ian C. Langtree.