A new study from The University of Texas at San Antonio found higher concentrations of several everyday chemicals in the primary teeth of children with autism compared with typically developing children. Researchers analyzed donated baby teeth from 22 children with autism and 16 typically developing children, finding an average of about 300 chemicals per participant in both groups. Of 60 compounds identified in more than half of the samples, 39 are known developmental toxicants or endocrine-disrupting compounds; 57 of the 60 (95%) had higher concentrations in the autism group, with 19 of them significantly higher. The study was published in Neurotoxicology and Teratology.
The study's distinctive feature is its use of teeth as a record of long-term exposure: human teeth begin forming in the womb around the fourth month of pregnancy and are fully formed by about age 3, incorporating chemicals from the body's environment as they develop. Lead researcher Lynne P. Heilbrun said blood or urine samples only show a specific window of time, while many chemicals break down within hours or days: "Teeth capture cumulative exposures over long periods of time. We need both."
The compounds showing the largest differences were chemicals used in everyday products: fragrances, food preservatives, flame retardants, plastic tubing (PEX), food packaging and containers, and skin-applied personal care and baby products. Researchers identified 11 compounds found in baby bottles; five of the nine compounds showing the greatest differences between the groups can migrate from plastic bottles. The team used two-dimensional gas chromatography and time-of-flight mass spectrometry to analyze the teeth.
The researchers repeatedly emphasized that the pilot study does not establish that the chemicals cause autism — and "does not mean baby bottles or any other specific products cause autism." Its significance, they say, is that children may be "chronically and repeatedly exposed" to a wider range of developmental toxicants than short-term exposure studies had identified, warranting larger case-control studies on long-term exposure and autism.
Exposure pathways include what a pregnant mother breathes, eats, or absorbs through her skin before birth, and afterward food, food containers, personal care and household products, air, water pipes, and products designed for babies and children. Practical steps for parents: reduce plastic food contact (for example, don't heat food in plastic bottles or containers) and check product ingredient lists — but there's no reason to panic; the science is far from settled.