By now, most Americans are likely to have heard about the major question surrounding autism spectrum disorders (ASDs): what causes autism? The debates surrounding this question are highly politicized and often acrimonious. Is there an autism epidemic? Is autism caused by purely genetic factors, purely environmental factors, or a combination of both? Is autism preventable and treatable? Is the increasing number of vaccines recommended for children putting them at risk?

The more contentious of these controversies is whether there's a link between Thimerosal (a mercury-based vaccine preservative) and autism. Several well-publicized studies reported in mainstream medical journals have found no evidence of a connection. However, because of parental concerns, in 2001, the FDA began to reduce the amount of Thimerosal in most vaccines. At this point, the most widely used vaccines contain only a "trace" amount of Thimerosal, yet the most recent data, gathered from children referred to the California Department of Developmental Services System from March 2007, show no decline in the incidence of autism in those children, but rather a continuing increase, reports WebMD.

Other studies have found a strong connection, and have critiqued the methodology of the studies that have found no connection. Last spring, a 9-year-old girl with autism, Hannah Poling, made history when a federal court ruled that she was predisposed to autism because of an underlying mitochondrial…