19 Chemical Compounds “Significantly Higher” in Autistic Children’s Baby Teeth According To Pilot Study

A new pilot study in Neurotoxicology and Teratology evaluated primary teeth from 22 children who have an autism diagnosis and 16 who do not, and found a significant difference in chemical exposure for the autism cohort. The sample size is very small, and the study does not prove causality, but it does suggest there may be an environmental component to autism that has frequently been dismissed.

Researchers at the University of Texas Health Science Center at San Antonio used two-dimensional gas chromatography and time-of-flight mass spectrometry to measure pesticides and plasticizers locked into dentin as teeth form. This occurs from roughly the fourth month of pregnancy through early childhood.

60 compounds showed up in more than half of the teeth evaluated, and 57 of them were higher in the autism group. 19 compounds were “significantly higher” according to the researchers. Out of the 60 chemicals evaluated, 39 of them are classified as developmental toxicants or endocrine disruptors, while the EPA does not have any developmental-toxicity data on the other 21 chemicals.

Benzyl Benzoate is a fragrance and food preservative that is also used as a medicated lotion to treat scabies and lice. Organophosphate esters are used as plasticizers and flame retardants. Caprolactam is the primary building block for nylon-6, a widely used synthetic polymer. Five out of the nine chemicals that were most significantly higher for the autism cohort are found in baby bottles. The authors mention several chemical-containing items that are often found in close proximity to babies, including PEX plumbing, food-contact plastics, foam and flame-retarded baby gear, and products rubbed into skin like lotions.

The study shows those who were later diagnosed with autism had a larger prenatal and early-life exposure to these chemicals, but the research cannot prove the environmental exposure was causal in nature. The authors suggest large case-control studies should be conducted to understand more about the association that was found in their research.

HHS Secretary Robert F. Kennedy Jr. has been calling for further investigation into environmental factors that may be having an effect on the increasing rates of autism that have been occurring over the past several decades. President Trump has also supported the initiative. When Secretary Kennedy first announced the agency would be conducting research into environmental triggers for Autism Spectrum Disorder, several mainstream publications and figures criticized the move and said he was wrong for stating environmental factors are playing a role.

Kennedy told reporters that he is not discounting genetic markers that have been linked to ASD, but stated they “don’t determine outcomes alone.” He added, “You need an environmental toxin. For example, only one in five smokers die from lung cancer due to genetic predispositions. Similarly, low glutathione production, MTHFR gene mutations, or high testosterone increase autism vulnerability, but an environmental trigger is required.”

CDC data tracking autism rates in eight-year-old children shows approximately one in 31 children born in 2014, which is nearly five times the rate it was for children born in 1994, when it was one out of 150 children. In 2013, there was an update from DSM-IV to DSM-V, which combined autistic disorder, Asperger’s, PDD-NOS, and childhood disintegrative disorder under one category of Autism Spectrum Disorder (ASD).

The CDC didn’t start utilizing the new definition until 2014-2016, but there was a substantial jump in the autism rate already from one out of 150 in the year 2000 to one out of 69 in 2012. There wasn’t a significant jump in the following surveillance years after the CDC adopted the new definition, but there was a continual increase in ASD prevalence that similarly matches the rate increase prior to the definitional change.

Another theory that has been presented for the increased rates is that there is more knowledge about the condition of ASD and better tools to capture milder cases that wouldn’t have been diagnosed previously. Walter Zahorodny, an assistant professor at New Jersey Medical School, countered this claim over a decade ago in 2013 when it was posited that the high rates of autism in New Jersey were a result of better diagnostic capture compared to other states.

Zahorodny points out that if the diagnostic capture theory were true, other states would catch up to New Jersey’s higher autism rate while New Jersey’s rate would flatten. The other states have caught up, but New Jersey’s rate did not flatten and continues to increase with each CDC surveillance update.

Zahorodny mentioned this issue during an April 2025 press conference alongside Secretary Kennedy. “There is better awareness of autism, but better awareness of autism cannot be driving disability like autism to increase by 300% in 20 years,” he said. “That’s what we saw in New Jersey.” Since 2002, the national CDC rate has risen by 390% while the New Jersey rate increased by 220%.

Boys are 3.4 times more likely to be diagnosed with autism than girls. During that 2025 press conference, Secretary Kennedy referenced the national autism rate of one in 20 boys (5%) while California is substantially higher with one in 12.5 boys (8%) being autistic.

The latest study reflects a concern that there may be environmental factors or triggers that are contributing to the rise in autism nationwide. The press release states, “Developmental toxicants or endocrine disruptors may affect biological processes involved in development. Many toxicants may also affect mitochondria, structures within cells responsible for producing energy and supporting cellular function.”

“There are several critical windows of exposure during pregnancy, especially in the first trimester, but it doesn’t stop there,” said Lynne Heilbrun, MPH, PhD, one of the lead authors on the study. “The central nervous system continues to develop after birth until around age 25.”

David Gimeno Ruiz de Porras, PhD, MSc, LPsy, the other lead author on the study, expressed concerns that chemicals are being developed and put into circulation faster than scientists can evaluate their potential risks. “There are hundreds of millions of compounds being produced and released into commercial use,” Gimeno Ruiz de Porras said. “Industry is moving much faster in producing chemicals for different uses than we can study them.” He added, “This was a small study, but it gives us ideas about what we could do in this line of research in the future.”