The ideologically based belief that autism is entirely genetic has been taking a beating in the past few years as an Autism Research Paradigm Shift has been taking place which focuses more attention on the possible environmental factors involved in causing autism disorders. And the evidence of possible environmental causes or triggers of autism disorders continues to accumulate.
The UC Davis Mind Institute study is a recent highlight of this shift towards open examination of environmental triggers and factors contributing to the increasing diagnoses of autism disorders. The The Interagency Autism Coordinating Committee Strategic Plan for Autism Spectrum Disorder Research - January 26, 2009 essentially codified the Autism Research Paradigm Shift with numerous elements of its Strategic Plan emphasizing possible environmental contributors and causes of autism disorders.
Now Catherine DeSoto has published a correlational study, Ockman's Razor and Autism: The case for developmental neurotoxins contributing to a disease of neurodevelopment, at Neurotoxicology doi:10.1016/j.neuro.2009.03.003 which finds that:
"within the state with the highest rate of ASD, the rate is higher for schools near EPA Superfund sites, t (332) = 3.84, p = .0001. The reasons for the rise in diagnoses likely involve genetically predisposed individuals being exposed to various environmental triggers at higher rates than in past generations.
The study is the subject of a synopsis by Heather Patisaul, Ph.D. of North Carolina State University, at Environmental Health News. Ms Patisaul explains that the Superfund sites frequently contain such pollutants as chloroethelyenes, benzene and metals (lead, mercury, cadmium, chormium, arsenic). She reports that the study found autism rates signficantly higher near the toxic Superfund Sites:
Rates of the disorder were one and a half times higher in the districts within 10 miles of the toxic sites. That translates into 1 child in 92 in districts closer to the sites compared to 1 child in 132 in the districts farther away. Schools within a 20-mile radius of Superfund sites had similar autism trends as the schools with 10 miles of the sites.
Ms Patisaul cautions that correlational studies such as this might first identify possible causal relationships but will require further information to verify any such association. Hopefully the studies necessary to verify or refute possible connections and causes will be conducted without unecessary delay.