Autism refers to a collection of disorders, usually diagnosed during childhood, that affect language and social skills.
For the study, Rzhetsky’s team analyzed nearly 100 million U.S. health insurance claims for a county-by-county look at rates of autism and intellectual disability. They also examined rates of genital malformations in boys — such as micropenis, undescended testicles and hypospadias (in which the urethral opening is on the underside of the penis).
Those genital malformations were used as an indicator of parents’ exposure to environmental pollutants, Rzhetsky said. The exact causes of those birth defects are not clear, but some studies have suggested that certain environmental toxins — including pesticides and lead — might play a role, he said.
In this study, county rates of genital birth defects ranged from none to just over 2 percent. Overall, the researchers found, for every 1 percent increase in those birth defects, the rate of autism rose by close to 300 percent.
Even accounting for county demographics, a strong link existed between rates of genital defects and autism, Rzhetsky said.
But the reasons for the correlation aren’t clear. Genes could play some role, Rzhetsky said, and so could environmental factors other than pollutants.
Halladay said endocrine disruptors — chemicals found in plastics, food cans and other everyday products — have been linked to genital birth defects. But so far, researchers haven’t found a connection to autism risk.
On the other hand, some studies have found a link between high exposure to air pollution during pregnancy and an increased autism risk, Halladay said.
via More Evidence Environmental Exposures Contribute to Autism.