JOE SCARBOROUGH, Host: Six out of every 1,000 kids get it, and nobody knows exactly why. But my next guest says ... part of the blame ... needs to fall on government. And it has to do with a drug called thimerosal. Robert F. Kennedy Jr. is a senior attorney for the Natural Resources Defense [Council]. Let's talk tonight about thimerosal. There are a lot of people out there ... very concerned about the impact of this drug, which is found in vaccines, and how it causes autism. Talk about that. ROBERT F. KENNEDY JR.: That's right. Thimerosal is a preservative that was put in vaccines back in the 1930s. Almost immediately after it was put in, autism cases began to appear. Autism had never been known before. It was unknown to science. Then the vaccines were increased in 1989 by the CDC and by a couple of other government agencies. What happened was the vaccine schedule was increased. We went up from receiving about 10 vaccines in our generation to these kids receive 24 vaccines. And they all had this thimerosal in them, this mercury. And nobody bothered to do an analysis of what the cumulative impact of all that mercury was doing to kids. As it turns out, we are injecting our children with 400 times the amount of mercury that FDA or EPA considers safe. A child on his first day that he is born is injected with a hepatitis B shot. Under EPA guidelines, he would have to be 275 pounds to safely absorb that shot. What happened was that, in 1988, one in every 2,500 American children had autism. Today, one in every 166 children have autism.