Autism is a neurological disorder affecting about one out of 68 children within the United States. Currently, researchers have found no one cause that offers a definitive explanation to why certain children develop autism, and if we’re going to figure out how to prevent this disease or improve autism treatments, it’s essential to understand the underlying causes. Recently, new research reported in Nature communications and done by the National Institute of Environmental Health Sciences discovered that in children with autism, their baby teeth contain higher levels of dangerous lead. Not only did the baby teeth contain more lead, they had less manganese and zinc, important minerals, than is found in most baby teeth.

Studying Autism, Understanding Heavy Metals

In order to eliminate both environmental and genetic influencers, researchers performed their studies on sets of twins. The findings of the studies suggest that there’s a link between exposure to metals and the way the body deals with them and the development of autism.

Baby teeth have growth rings, and lasers were used by scientists to follow these growth rings, looking carefully at them throughout different developmental stages of life. The differences in metal uptake was most pronounced before and after birth, and while there were higher levels of lead in the autistic children throughout development, the biggest difference was found right after birth. When it came to zinc levels, autistic children had much lower levels of the metal before they were born, but after birth the levels of zinc appeared to normalize.

These discoveries have lead researchers to think that autism begins very early while the child is still in the womb, and the environment may increase the child’s risk of autism. When children are diagnosed with autism when they’re between the ages of three and five, it’s tough to look back and figure out what their mothers may have been exposed to. Now, baby teeth allow researchers to look back to find out what children may have been exposed to in the past to cause the development of autism.

Previous research has shown that exposure to toxic metals like lead and deficiencies in essential nutrients can be harmful to the brain in early childhood and even in utero. Both low levels or high levels of manganese appear to be harmful to the developing brain in children, not only increasing the risk of autism, but the severity of autism as well.

Linking Autism and Heavy Metals

These recent studies were led by Manish Arora, Ph.D., a dentist and environmental scientist that works at the Icahn School of Medicine, and he was able to create a way to look at baby teeth to analyze heavy metal exposure. He noted that the environment and genes both probably influence the development of autism, but it’s been difficult in the past for researchers to pinpoint the exact things in the environment that resulted in an increased risk of autism.

Arora wanted to find a way to discover what happened in fetal life. Unlike a baby’s genes, the environment always changes. The response to any environmental stressors depends on how much the body was exposed to and the age at what exposure occurred. Many studies have already looked at the levels of lead in children who have already been diagnosed with autism, but this new study allowed researchers to measure what children were exposed to a long time before they were diagnosed, which offers a huge advantage that may change the way autism is treated in the future. By looking at the levels of toxic metals in teeth at around three months after birth, it may be possible to predict the development of autism and its severity in the future.

By looking at baby teeth, researchers have been able to identify the period in life when the developing brain is most susceptible to exposure to toxic metals. It’s possible that looking at baby teeth may prove useful for researcher many other developmental disorders as well. The medical community continues to be excited about the potential of baby teeth to provide a deeper look at a child’s early life and what they are exposed to, and researchers hope to be able to offer clinical recommendations in the future to help prevent developmental disorders.