Is Comet Water Toxic?

[tetrahedron]

I was watching one of those 'The Universe' shows on television and it occurred to me- since water in space hasn't had deuterated species separated out, it would have much higher concentrations of this stuff than earthly water. Would it be enough to kill you if you drank a couple of gallons of it, or would it just make you sick?

 

Jess Tauber

[exchemist]

I was watching one of those 'The Universe' shows on television and it occurred to me- since water in space hasn't had deuterated species separated out, it would have much higher concentrations of this stuff than earthly water. Would it be enough to kill you if you drank a couple of gallons of it, or would it just make you sick?

 

Jess Tauber

Probably neither.

 

D2O acts much the same as H2O in biochemistry, although some of the kinetics and bonding will be slightly different. It appears you would probably not experience ill effects until a large proportion of your water was D2O. Here is the relevant part of the Wiki article on heavy water:  

 

 

Toxicity in humans[edit]

Because it would take a very large amount of heavy water to replace 25% to 50% of a human being's body water (water being in turn 50–75% of body weight^[38]) with heavy water, accidental or intentional poisoning with heavy water is unlikely to the point of practical disregard. Poisoning would require that the victim ingest large amounts of heavy water without significant normal water intake for many days to produce any noticeable toxic effects.

Oral doses of heavy water in the range of several grams, as well as heavy oxygen ¹⁸O, are routinely used in human metabolic experiments. See doubly labeled water testing. Since one in about every 6,400 hydrogen atoms is deuterium, a 50 kg human containing 32 kg of body water would normally contain enough deuterium (about 1.1 g) to make 5.5 g of pure heavy water, so roughly this dose is required to double the amount of deuterium in the body.

A loss of blood pressure may partially explain the reported incidence of dizziness upon ingestion of heavy water. However, it is more likely that this symptom can be attributed to altered vestibular function.^[39]