What is a dangerous liquid or powder?

Answer 1

Ok....... You'll never guess............... but water. If you drink too much water you will die. Don't worry! You'll have to drink like... 100 gallons of water. But... it is pretty shocking.

Alternate Answer:

I don't disagree that water causes more damage, injuries and deaths than any other liquid. This is largely due to floods, drowning, etc (I imagine the "drinking 100 gallons of water" Death Rate is pretty low). Water is simply the most common compound on the planet.

In spirit of what I believe is the true heart of the question, I'm going to propose a chemistry-related answer: Dimethylmercury. As little as one drop of this stuff has proven fatal. It is absorbed into the skin almost immediately which can result in Mercury poisoning. It's highly volatile (meaning it vaporizes easily) and can result in respiratory failure if inhaled. And on top of all that, most PPE (personal protective equipment) is ineffective. It will soak through latex and neoprene gloves in a manner of a few seconds!

I'd be curious to hear any other alternative answers.