Thimerosal and autism:

From a Danish study:

"There was no trend toward an increase in the incidence of autism during that period when thimerosal was used in Denmark, up through 1990. From 1991 until 2000 the incidence increased and continued to rise after the removal of thimerosal from vaccines, including increases among children born after the discontinuation of thimerosal. "

From wikipedia:

2001- The Institute of Medicine, citing insufficient evidence, is unable to prove or disprove any link between thiomersal and autism. However, they conclude that a causal connection between thiomersal and autism is "biologically plausible".

2004- The Institute of Medicine, based on new information from epidemiological studies undertaken since its 2001 report, rejects the hypothetical causative link between thiomersal and autism.