The federal "special vaccine court" ruled Friday that parents who said their children's autism was caused by a preservative did not prove their case and are not entitled to compensation.

The cases, brought by the children's parents, all alleged that vaccines containing thimerosol, a mercury preservative, caused or contributed to autism spectrum disorders in their children.

Thousands of parents of children with autism have filed petitions seeking compensation from the Department of Health and Human Services' Vaccine Injury Compensation Program, a federal program intended to compensate victims of injuries caused by vaccines, since 2001.

A panel of "special masters" began hearing three test cases in 2007 brought by parents of children with autism who also had said vaccines caused the disorder in their children.

In February 2009, a special court ruled that no link between autism and certain early childhood vaccines could be proven based on evidence presented in the three cases brought in 2007.

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