When Ann Dachel of Eau Claire brought her son John in for a routine vaccination, she never expected his behavior was about to change.

"He didn't pick up on things around the time that he was 18 months to two-years- old, he wasn't speaking, he stopped babbling, I never would have connected that to vaccinations," Dachel said.

But, after some research on her own, she soon did, discovering what she calls a clear connection between the increasing autism rate and rising exposure to vaccines with toxic substances like aluminum, MSG, formaldehyde and mercury.

"Our kids in the 1990's were getting just enormous load of mercury in their vaccines and that's when autism really exploded," she said.

Ann's theory has some backing in the academic research world. Dr. Boyd Haley, a leading University of Kentucky Researcher on the topic says thimerosal, a vaccine preservative with nearly 50 percent mercury has contributed to epidemic levels of autism in the US.

"Thimerosal is one of the most neuro-toxic compounds that's available or that we could even reasonably be exposed to, so common sense says you would look at that first and you would look at that very, very hard," Haley said.

But, he says CDC research has been limited to population studies in Europe, areas he says don't have the high rate of vaccination we have here.

He also says the CDC mandated the vaccine program in 1988 without any safety testing. However, according to a statement by the CDC scientific evidence does not support the idea that vaccine causes autism.

"The amount of mercury they are injecting into these babies on the day of birth would be safe by EPA standards eating fish, if the baby weighed 275 pounds," Haley said.

Dr. Haley says infants can't excrete mercury and though mercury isn't always found in the urine, hair or blood of children with autism, Arizona State Researchers have found considerably more mercury in their baby teeth than those without.

Eau Claire Health Department Director Richard Thoune believes the benefits of vaccines, outweigh the risks.

However, Dr. Haley says because of it's toxicity, the FDA took thimerosal off the market as a topical application in 1978, but it is still found in flu vaccine.