Environmental pollution might be contributing to autism risk, according to a recent study HealthDay reported.

Researchers from the University of Chicago found that autism and intellectual disability (ID) rates are correlated at the county level with incidence of genital birth defects in newborn males, an indicator of possible congenital exposure to harmful environmental factors such as pesticides, HealthDay reported.

Male fetuses are particularly sensitive to toxins such as environmental lead, sex hormone analogs, medications and other synthetic molecules. Parental exposure to these toxins is thought explain a large portion of congenital reproductive malformations.

"Autism appears to be strongly correlated with rate of congenital malformations of the genitals in males across the country," study author Andrey Rzhetsky, professor of genetic medicine and human genetics at the University of Chicago, said in a statement. "This gives an indicator of environmental load and the effect is surprisingly strong."

For the study, researchers analyzed an insurance claims dataset that covered nearly one third of the US population. They used congenital malformations of the reproductive system in males as an indicator of parental exposure to toxins.

Based on their findings, 1 percent increase in malformations in a county was associated with a 283 percent increase in autism and 94 percent increase in intellectual disability in that same county. Almost all areas with higher rates of autism also had higher rates of intellectual disability, which the researchers believe corroborates the presence of environmental factors.

They also found that male children with autism are almost six times more likely to have congenital genital malformations. Female incidence was linked with increased malformation rates, but weakly so. A county-by-county map of autism and ID incidence above or below the predicted baseline for the entire US is included in the study.

We interpret the results of this study as a strong environmental signal," Rzhetsky said. "For future genetic studies we may have to take into account where data were collected, because it's possible that you can get two identical kids in two different counties and one would have autism and the other would not."

The study was published by scientists from the University of Chicago on March 13 in PLOS Computational Biology.