A March 16, 2007 piece by Kathleen Doheny about e-mailed health rumors has some sound advice from ACSH's Jeff Stier:
"If the email is the only place you are seeing it [information about the hazard], there is a reason," says Jeff Stier, spokesman for the American Council on Science and Health, in New York. If you don't see or hear the same information on the nightly news, a mainstream newspaper, or a credible web site, be suspicious, he says.
And for some advice on how to avoid falling for everything you hear on TV and in newspapers as well, check out ACSH's Good Stories, Bad Science: A Guide for Journalists to the Health Claims of "Consumer Activist" Groups.