Baby Teeth Are Giving Researchers a New Look at Autism and Early-Life Chemical Exposure

A child’s baby tooth may hold clues about what happened long before that tooth ever fell out.

In a small new study, researchers found striking differences in the chemical traces preserved in the baby teeth of children with autism compared with those of typically developing children. The analysis detected roughly 300 chemicals per participant on average, and 57 of the 60 compounds found most frequently were present at higher concentrations in the autism group.

The findings, published in Neurotoxicology and Teratology, are likely to raise questions about everyday chemical exposure during pregnancy and early childhood. But they do not show that those chemicals cause autism. The researchers describe the work as preliminary and say much larger studies are needed.

The Tooth Was The Time Capsule

Baby teeth begin forming at around 13 to 14 weeks of pregnancy and continue developing through early childhood.

As they form, they can retain traces of substances encountered during that period.

That gives researchers something blood and urine often cannot: a record that stretches across months and years rather than capturing a relatively narrow moment.

“Teeth capture cumulative exposures over long periods of time, whereas blood or urine samples only show a specific window of time. We need both,” lead author Lynne P. Heilbrun, PhD, MPH, said.

The researchers analyzed donated teeth from 38 children, including 22 children with autism and 16 typically developing children.

They used targeted and non-targeted chemical screening, allowing them to look broadly for compounds rather than limiting the analysis to a short list of substances selected in advance.

Nearly Every Frequently Detected Chemical Was Higher

Of the roughly 300 chemicals detected per participant, the researchers focused on 60 compounds found in more than half of the tooth samples.

The difference between the two groups was notable.

Fifty-seven of those 60 compounds, or 95%, were present at higher concentrations in the teeth from children with autism. Nineteen were significantly higher.

Researchers classified 39 of the 60 compounds as developmental toxicants or endocrine-disrupting compounds.

That language requires some unpacking. A developmental toxicant or endocrine-disrupting compound is not automatically a cause of autism. Those classifications describe potential biological effects or hazards associated with chemicals.

The study found an association between chemical levels and autism status. It did not establish cause and effect.

Some Chemicals Are Tied To Everyday Products

The compounds identified in the study included pesticides and plasticizers, with possible connections to categories such as fragrances, food-contact materials, personal-care products, flame-retardant materials, plumbing products, and baby products.

One compound the researchers highlighted was benzyl benzoate, which can be used in fragrances and as a food preservative. The study also identified organophosphate esters, a class of chemicals used as plasticizers, flame-retardant materials, and in other consumer or industrial applications.

But there is an important distinction between finding a chemical in a tooth and knowing where it came from.

The researchers did not trace the compounds to specific brands or household products used by the children. The study therefore cannot tell a parent that a particular bottle, food package, fragrance, or cleaning product caused a child’s exposure.

The Baby-Bottle Finding Needs A Big Asterisk

Image Credit: chalabala via 123RF

The researchers identified 11 compounds associated with baby bottles.

Five of the nine compounds that most strongly differentiated the two groups were capable of migrating from baby bottles.

That sounds alarming until you look at what the study actually tested.

Researchers did not test the children’s bottles. They didn’t know which brands families used, how often the bottles were used, or whether the children were exposed to those chemicals through the bottles at all.

So this finding is better understood as a lead for future research, not a warning to throw out every plastic baby bottle.

The FDA has also said BPA-based materials are no longer authorized for baby bottles, sippy cups, or infant-formula packaging in the U.S. That regulatory context matters when interpreting the new findings.

Related: 7 Signs of Autism in Adults That Often Go Unnoticed

One In Five Chemicals Had Another Problem

Of the 60 frequently detected compounds, 21 did not have EPA developmental-toxicity information available, according to the study.

That creates a bigger question than the autism findings alone: How much do researchers actually know about the potential developmental effects of the chemicals children encounter?

The study does not answer that question. But the gap is significant enough for the researchers to call for additional work.

Senior author David Gimeno Ruiz de Porras, PhD, MSc, LPsy, put the study in that context.

“This was a small study, but it gives us ideas about what we could do in this line of research in the future,” he said.

There Is Already A Trail Of Baby-Tooth Research

Earlier researchers have also used shed baby teeth to investigate biological differences associated with autism.

A 2024 exploratory study found an average of 99.4 detected organic chemicals in teeth from children with autism compared with 80.7 in teeth from the comparison group.

A 2017 study examined metals in baby teeth and reported differences in lead and manganese patterns between children with and without autism.

Other researchers have used tooth layers to investigate inflammation during prenatal and early postnatal development.

The studies do not produce one simple answer. They instead add pieces to a much larger puzzle involving genetics, biology, development, and environmental exposures.

The Biggest Question Remains Unanswered

The obvious question is whether the chemical differences played a role in autism.

This study cannot tell us.

The researchers did not establish when a particular exposure occurred, identify its source, or determine whether exposure preceded developmental differences associated with autism. And with only 38 children, the study is far too small to establish a population-wide pattern.

Autism is also not understood to have one single cause. Federal health agencies describe autism as involving multiple genetic, biological, and environmental factors.

That makes the distinction between association and causation especially important here.

A child having higher concentrations of a chemical in a baby tooth does not mean that chemical caused autism.

What Researchers Want To Do Next

The study’s 38-child sample is far too small to determine whether the same chemical pattern exists across the broader population. Larger research could examine whether the findings are replicated, whether particular developmental periods matter more, and whether specific exposure sources can be identified.

The CDC estimates that 1 in 31 U.S. children age 8 were identified with autism in 2022 across the communities included in its surveillance network. That figure highlights the scale of interest in autism research, but it does not point to any particular environmental cause.

For now, the baby-tooth study offers something more limited but potentially valuable: a way to look backward at chemical exposure during a period that is otherwise difficult to reconstruct.

And the researchers’ findings make clear that there are still many unanswered questions about what those chemical traces mean.

If your child’s baby tooth could tell a story about early life, what would you want to know?