Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: Nobody's Confidant on 19/10/2007 17:22:09

Title: Heavy water.
Post by: Nobody's Confidant on 19/10/2007 17:22:09

Hydrogen-2. Is it dangerous? Radioactive or anything.

Title: Heavy water.
Post by: Bass on 19/10/2007 20:34:02

Deuterium is radioactively stable, but tritium and heavier isotopes of hydrogen decay.  I believe heavy water is toxic once the deuterium levels reach a certain threshold.

Title: Heavy water.
Post by: Bored chemist on 20/10/2007 18:31:46

Heavy water is toxic but you probaly couldn't afford enough to poison someone.
Here's what wiki has to say on the matter
Toxicity in humans
Because it would take a very great deal of heavy water to replace 25% to 50% of a human being's body water (70% of body weight) with heavy water, accidental or intentional poisoning with heavy water is unlikely to the point of practical disregard. For a poisoning, large amounts of heavy water would need to be ingested without significant normal water intake for many days to produce any noticeable toxic effects (although in a few tests, volunteers drinking large amounts of heavy water have reported dizziness, a possible effect of density changes in the fluid in the inner ear). For example, a 70 kg human containing 50 kg of water and drinking 3 liters of pure heavy water per day, would need to do this for almost 5 days to reach 25% deuteration, and for about 11 days to approach 50% deuteration. Thus, it would take a week of drinking nothing but pure heavy water for a human to begin to feel ill, and 10 days to 2 weeks (depending on water intake) for severe poisoning and death. In the highly unlikely event that a human were to receive a toxic dose of heavy water, the treatment would involve the use of intravenous water replacement (due to possible intestinal dysfunction and problems with absorption of fluids). This would be done via 0.9% (normal physiologic) saline solution with other salts as needed, perhaps in conjunction with diuretics.

Oral doses of heavy water in the multi-gram range, along with heavy oxygen 18O, are routinely used in human metabolic experiments. See doubly-labeled water testing. Since 1 in every 6400 hydrogen atoms is deuterium, a 50 kg human containing 32 kg of body water would normally contain enough deuterium (about 1.1 gram) to make 5.5 grams of pure heavy water, so roughly this dose is required to double the amount of deuterium in the body.

Title: Heavy water.
Post by: Nobody's Confidant on 24/10/2007 17:30:52

Oh i see. I heard about heavy water reactors somewhere, what are those?

Title: Heavy water.
Post by: Bored chemist on 24/10/2007 19:32:26

Probably nuclear reactors using heavy water as a moderator.
This sort of thing
http://en.wikipedia.org/wiki/CANDU