Researchers at The University of Texas Health Science Center at San Antonio did an analysis of Texas school district data and industrial mercury-release data that showed a statistically significant link between increased autism rates and pounds of industrial release of mercury emitted.

Raymond F. Palmer said the study showed -- for the first time in scientific literature -- a statistically significant association between autism risk and proximity to the mercury source.

"This is not a definitive study, but just one more that furthers the association between environmental mercury and autism," Palmer said in a statement. "This study was not designed to understand which individuals in the population are at risk due to mercury exposure, however, it does suggest generally that there is greater autism risk closer to the polluting source."

The researchers reported in the journal Health & Place that the community autism prevalence is reduced by 1 percent to 2 percent with each 10 miles of distance from the mercury pollution source.