Idézet: MartinBV - 2011.06.23. 23:17:26 Idézet: Wtfakkeltje - 2011.06.23. 17:45:58 Which of these is poisonous?
Iron
Mercury
Titanium
Hydrogen
Obviously, you wouldn't want to be drinking mercury. But I'm sure the other options would do pretty much the same thing to you if you ingest them.
"All things are poison, and nothing is without poison; only the dose permits something not to be poisonous."
-Philippus Aureolus Theophrastus Bombastus von Hohenheim
That might be so, but your blood consists loads of iron, in fact it's pretty vital to your survival. Hydrogen is also abundant in every cell in your body, so calling it poisonous is the same as calling water poisonous, literally. Titanium is used in most sunscreen and loads of cosmetics, as well as in jewelery, and body implants, precisely because it's non-toxic, that leaves mercury. I sure wouldn't want any of that on my skin or in my food.
Actually, water can be poisonous: http://en.wikipedia.org/wiki/Water_intoxication.
Iron, while vital for life, can also be poisonous: http://en.wikipedia.org/wiki/Iron_poisoning
Even titanium, considered in many cases to be inert, can be poisonous: http://consumercide.com/health/dent-toxtitanium.html
The entire thing is that when you start looking at things in more detail, everything is potentially poisonous, it is only a question of dosage. Morphine for example is used as a pain killer, but a small increase in dosage and you stop breathing.
Of the substances mentioned in the question, Mercury is the most poisonous. Even then, mercury is not acutely toxic (i.e. you don't die immediately from getting it in your food or on your skin) but rather mercury causes damage that can kill you hours or even months later.
Simply chaining the question to "Which of these substances are the most poisonous to humans?" would solve everything.