heavy water

Tom Thatcher ttha at uhura.cc.rochester.edu
Wed Apr 12 21:41:02 EST 1995

In <1995Apr11.191116.14955 at henson.cc.wwu.edu> n8010095 at henson.cc.wwu.edu (Phillip Bigelow) writes:

>>> Can anyone tell me the chemical formula for heavy water and in what dosage
>>> is it harmful. Also what are the symptoms of someone who has ingested too
>>> much.

>>>                                        -Wendy Wolk
>>>                                          USC Cinema/TV

>:>The formual for heavy water is D2O (D = deuterium).  You have to consume a
>:>huge amount of heavy water for it to be toxic.

>  What would be the symptoms?  Also, would consuming air/water/food that
>contains pure O18 (heavy oxygen) also be pathologic?

Heavy oxygen is no problem at all.  Chemically, O18 behaves just like O16.
D2O is somewhat different.  For example, there are enzymes called proton
pumps whose job is to push Hydrogen ions (protons or H+) across membranes
to set up pH or voltage gradients.  Although the deuterium ion (D+) has
the same charge, the pump may not work as well since D+ is heavier.

Concentrations of D2O in culture media of 50-70% arrest cell division 
because the D+ interferes with microtubule stability.

To get a concentration of D2O in the body of 70%, you would have to 
consume 100% D2O probably for days or weeks.  There is literature on
whole body water turnover rates.  A volunteer drinks some marked water
(either D2O or O18 marked).  You measure how much is retained and how 
much is immediately excreted.  Then watch as the retained water is slowly
diluted out by new intake.  Someone more knowlegable in physiology than
I could use this info to calculate how long it would take to 70%
a person with D2O assuming daily intake of so many liters of 100% D2O.

Now, here are some educated guesses on toxicity, based on knowing which
organs use proton pumps.
Because proton balance is very important in the bowels, one of the first
symptoms would be diarrhea, followed by kidney failure, general weakness,
and neurological failure (A hydrogen/Sodium/Potassium pump is critical 
for setting up nerve electrical potential).  Neurological symptoms would
begin with weakness, then tremors, the paralysis and death.

Tom Thatcher                          | You can give a PC to a Homo habilis,
University of Rochester Cancer Center | and he'll use it, but he'll use it
ttha at uhura.cc.rochester.edu           | to crack nuts.

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