Henry Baker> What makes D2O toxic?
I wondered too! Excerpts from the top 2 Google results for "heavy water toxicity" are below.
-- Mike
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>If I recall correctly, there was an experiment done some years ago with
>mice and deuterium. The mice were fed normal food, but given pure deuterium
>instead of, "water". As I remember, the mice died of dehydration.
>The cells were unable to use the deuterium.
Not the kind of dehydration you're probably thinking of, though. When
body deuterium reaches about 50%, it inhibits mitosis because spindle
microtubules won't form (some hydrogen bond effect inhibiting
self-polymerization, I think). So all eucaryotic cells are poisoned
at about these concentrations, or a little higher (bacteria can
survive full deuteration -- they just grow half as fast). The
consequences of failure of cell division for an intact animal like a
rodent, are somewhat like those of radiation or chemo -- the bone marrow
and gut lining cells suffer. Animals die of infection or diarrhea.
That might make a good cerebral mystery for a student text: a person
with full control of an elderly relative deuterates them to death over
a couple of weeks to a month (which would take about 50 kg of heavy
water at $300 a kg, but nevermind). Forensics thinks the person died
of some strange disease or poison, but can't identify one (since they
don't routinely do any tests to identify D!). The detective only
recognizes something's amiss when the bad guy offers him ice in his
lemonade, and has forgotten to dump the ice in the icebox, which is made
from heavy water. Detective notices the ice SINKS in his glass.
Hmmmm.
Steve Harris, M.D.
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Despite the fact the light water and heavy water are chemically identical,
heavy water is mildly toxic. How can this be? Since heavy water is heavier
than normal water, the speed of chemical reactions involving it is altered
somewhat, as is the strength of some types of bonds it forms. This affects
certain cellular processes, notably mitosis, or cell division, due to the
difference in binding energy in the hydrogen bonds needed to make certain
proteins. Mouse studies have shown that drinking only heavy water along with
normal feed eventually causes degeneration of tissues that need to replenish
themselves frequently, and leads to cumulative damage from injuries that
don't heal as quickly. One study likens the effects to those suffered by
chemotherapy patients. Heavy water toxicity manifests itself when about 50%
of the water in the body has been replaced by D2O. Prolonged heavy water
consumption can cause death.
Don't get any funny ideas about using heavy water as a virtually untraceable
and undetectable murder weapon, though. Given its role in breeder reactors
for producing weapons-grade plutonium, production and distribution of heavy
water is closely monitored and controlled. Obtaining a significant amount is
damn near impossible for the average Joe, and you'd need a LOT of it to
kill anyone. It's also expensive--one estimate puts the price at about
$300 per kilogram. Hit 'em over the head with a bottle of Poland Spring
and save yourself some grief.
--SDSTAFF Q.E.D.
Straight Dope Science Advisory Board
