In June of 2000, members from the Centers for Disease Control, the Food and Drug Administration, and pharmaceutical companies, met in a secret meeting held in Simpsonwood, GA. The topic of discussion was the relationship between thimerosal and autism.
We know what was said at the meeting because parents obtained the transcripts through the Freedom of Information Act. The conversations are chilling. 
Here are three important quotes from the Simpsonwood Document:
“…the number of dose related relationships [between mercury and autism] are linear and statistically significant. You can play with this all you want. They are linear. They are statistically significant.” – Dr. William Weil, American Academy of Pediatrics. Simpsonwood, GA, June 7, 2000
“Forgive this personal comment, but I got called out at eight o’clock for an emergency call and my daughter-in-law delivered a son by c-section. Our first male in the line of the next generation and I do not want that grandson to get a Thimerosal containing vaccine until we know better what is going on. It will probably take a long time. In the meantime, and I know there are probably implications for this internationally, but in the meanwhile I think I want that grandson to only be given Thimerosal-free vaccines.” – Dr. Robert Johnson, Immunologist, University of Colorado, Simpsonwood, GA, June 7, 2000
“But there is now the point at which the research results have to be handled, and even if this committee decides that there is no association and that information gets out, the work has been done and through the freedom of information that will be taken by others and will be used in other ways beyond the control of this group. And I am very concerned about that as I suspect that it is already too late to do anything regardless of any professional body and what they say…My mandate as I sit here in this group is to make sure at the end of the day that 100,000,000 are immunized with DTP, Hepatitis B and if possible Hib, this year, next year and for many years to come, and that will have to be with thimerosal containing vaccines unless a miracle occurs and an alternative is found quickly and is tried and found to be safe.” – Dr. John Clements, World Health Organization, Simpsonwood, GA, June 7, 2000