Baby Teeth May Hold Clues to Autism Risk, Study Says

There's a new clue out there about the risk for autism spectrum disorder in children – and if studied

and proven further, could open new avenues of research on other disorders.

The new study from the National Institute of Environmental Health Sciences at the National Institute of Health examined children's baby teeth to find any possible correlation between exposure to certain metals, both toxic and nutritional, and risk of autism spectrum disorder. The results found children with autism had a greater amount of toxic lead and lesser amount of nutrients zinc and manganese as opposed to other children.

The study suggests exposure to metals at a young age or how a body processes such metals could impact autism risk.

Researchers looked at teeth from 32 pairs of twins and 12 individual twins, taking into account whether just one of the twins had autism or if both or neither had it. Most of the differences in metal exposure were found in the months leading up to and the months after children were born, with higher levels of lead over the course of development for those with autism. The time just after birth had the largest disparity.

In order to do the analysis, researchers led by New York-based environmental scientist and dentist Manish Arora used lasers in extracting dentine – the substance under tooth enamel. This work builds on prior research, as these researchers already found the lead in these dentine layers correlates with lead exposure across multiple developmental periods.

"A lot of studies have compared current lead levels in kids that are already diagnosed," Cindy Lawler, who leads a branch of the NIEHS, said in a news release. "Being able to measure something the children were exposed to long before diagnosis is a major advantage."

"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," Lawler continued. "With baby teeth, we can actually do that."

And the buck doesn't just stop at autism spectrum disorder – the baby teeth method could also prove helpful when it comes to researching other disorders like attention deficit hyperactivity disorder, according to the news release. "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, head of the NIEHS Exposure, Response, and Technology Branch.

Researchers say more comprehensive studies are needed to further assess the link between autism and metal exposure.