A new study indicates that child autism rates may be higher in areas that have more precipitation.
The study, which appears in November’s Archives of Pediatrics and Adolescent Medicine, examined autism rates for children in selected counties in Washington, Oregon, and California, as well as precipitation rates for those areas from 1987 to 2001.
"These results are consistent with the existence of an environmental trigger for autism among genetically vulnerable children that is positively associated with precipitation," wrote Michael Waldman of Cornell University and his colleagues.
The researchers estimated that the presence of an environmental trigger had increased 2005 autism rates in the studied counties by as much as 43 percent. They also suggested their findings "could potentially be explained by any environmental exposure associated with indoor activities."
In 2007, the Centers for Disease Control and Prevention determined that about 1 in 150 8-year-olds in selected areas of the United States suffer from an autism spectrum disorder (ASD). The CDC estimates that this would amount to approximately 560,000 Americans aged 1 to 21 suffering from an ASD.