A small pilot study found higher levels of 19 potentially harmful chemicals in the baby teeth of children later diagnosed with autism, but researchers stress that the findings do not prove cause and effect.
Scientists are adding to evidence that the earliest roots of autism may involve more than genes alone, with a new pilot study suggesting that children later diagnosed with the condition had higher levels of a range of potentially harmful chemicals in their baby teeth than children without autism. The research does not show that any of the substances caused autism, but it adds to a growing body of work examining how prenatal and early-life exposures may shape development.
The findings matter because many studies of environmental exposure rely on blood or urine, which capture only a short snapshot of what is in the body. Teeth, by contrast, can preserve a chemical record as they form. According to the University of Texas at San Antonio researchers behind the study, primary teeth begin recording exposure in the womb and continue until around age three, creating a longer-term archive of substances a child encountered before the teeth fall out several years later.
In the small study, researchers examined shed baby teeth from 38 children, including 22 with autism and 16 in a comparison group. Using advanced chemical analysis, they found more than 300 toxicants on average in each sample. Of the 60 compounds detected in at least half of the children, about two-thirds were substances that the Environmental Protection Agency classifies as developmental or reproductive toxicants or endocrine disruptors, according to the researchers. Nineteen of the differences between the two groups were statistically significant, including a strikingly higher concentration of benzyl benzoate in the autism group.
The compounds identified included chemicals associated with pesticides, plastics, fragrances, flame retardants and sunscreen products. The researchers also said they detected 11 compounds previously reported to migrate from baby bottle components, alongside substances linked to baby products, food contact materials, plastic tubing and indoor furnishings. Many of the chemicals flagged in the study are known to affect the brain, liver or mitochondria, but the authors stressed that the work was exploratory and based on a small sample.
The study lands in an area of active scientific interest. The National Institute of Environmental Health Sciences says research into autism increasingly looks at environmental contributors as well as genetics, and a 2017 review published in the journal Systems Biology in Reproductive Medicine said environmental factors may account for a substantial share of autism spectrum disorder variation. Other research cited by NIEHS has linked traffic-related air pollution during pregnancy with a higher likelihood of autism in children, reinforcing the idea that exposure timing may be as important as the chemical itself.
For parents, the key point is that this study raises questions rather than answers them. It does not establish a cause-and-effect link, and the researchers themselves say larger studies are needed. But it does suggest that baby teeth could become a useful tool for tracing early chemical exposure, and it strengthens calls from the study team for more caution around chemicals that pregnant women, infants and young children encounter through everyday products.
Disclaimer: This content is for informational purposes only and is not intended to be a substitute for professional medical judgment, advice, diagnosis, or treatment.
