While the mercury-based preservative thimerosal hasn't been used in any childhood vaccine in Ontario since the 1960s - or in any other province since the late 1990s - it is contained in this year's flu vaccine, a Health Canada spokesperson said.

The U.S. study, published this week in the journal Molecular Psychiatry, found an apparent link between thimerosal and autism in tests on human brain cells in test tubes.

[Ron Gold], professor emeritus of pediatrics at the University of Toronto, said no major study has found a link between thimerosal and autism or any other forms of brain damage.