Deepening the mystery surrounding the causes of autism, researchers have found a link between high levels of precipitation and increased rates of autism -- a disorder that affects one in 150 American children.
In a study to be released today in November's Archives of Pediatric and Adolescent Medicine, Cornell University economist Michael Waldman found that in areas of California, Oregon and Washington that experienced high levels of rain and snowfall during the years 1987-2001, autism rates among school-aged children rose when measured in 2005. Those children diagnosed with autism would have been under 3 during the periods of high precipitation, the period during which autism is generally diagnosed.
Both Waldman and Dr. Noel S. Weiss of the University of Washington, Seattle, who wrote an editorial about the study in the Archives, cautioned that the findings are very preliminary and stressed that they opened a world of possible explanations for autism besides rainfall itself. High levels of precipitation could mean kids spend more time indoors exposed to household toxins such as cleaning products, or watching TV. Both are hypothesized factors in the development of the disorder. The kids could spend less time in the sunshine, suppressing their bodies' production of Vitamin D, Waldman suggested. Or the link could suggest a more direct role of rainfall in giving rise to autism, he wrote, washing some toxin into drinking water or something else to which children are exposed.
Weiss suggested that the data from which Waldman drew his autism statistics could be unreliable, as diagnoses and records of those diagnoses vary from state to state and county to county.
-- Melissa Healy