Here's a YouTube clip of a Penn and Teller stunt in which people were convinced to sign a petition to ban "dihydrogen monoxide," also known as water.
When I was a Wired editor back in the 1990's, another Wired editor and I sent around email to the company with an anti "dihydrogen monoxide" screed ("I even saw our chef wiping down the counter with this stuff — it kills hundreds of people a year!")
Link (Bonus — super old Boing Boing vestigial page about deadly "dihydrogen monoxide.") (Thanks, Coop!)
Reader comment:
Grayson says:
DHMO information site. They have links to the CDC and EPA (and more), so they're for reals.
Also, Snopes has a story about a 14 year old's 1997 high school science project using info nearly identical to yours.