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Bad research, over-protective society and a hoax website conspire to encourage a Californian city to put forward a motion for a ban on dihydrogen monoxide :

And it got worse: dihydrogen monoxide is lethal if inhaled, causes severe burns in its gaseous state, and is the major component in acid rain. Prolonged exposure to solid dihydrogen monoxide can cause severe tissue damage. It can, said the city council report, “threaten human safety and health”.

Sounds dangerous, doesn’t it? Until you learn its more common name: water. Maybe not then.