Re: barium chloride (a bit long)
|From:||"J. A. Kiernan" <email@example.com>|
On Mon, 30 Jul 2001 NLOUISEA@aol.com wrote:
> We use a commercially prepared fixative containing Barium chloride in 10%
> NBF. After reading your email about the toxicity of barium chloride I'm
> concerned about disposing of it.
In my reply to your Histonet query. I think I mentioned
that barium sulphate is completely non-toxic because it is
completely insoluble in pretty well everything. A barium meal
X-ray investigation consists of swallowing a pint or so of
a thick suspension of BaSO4 (must contain at least 200 gm)
which ends up being flushed down the loo the next day.
All you have to do to make your barium chloride as harmless
as sand is to add an equimolar or greater amount of any
soluble source of sulphate ions. The second cheapest is
sodium sulphate, Na2SO4.10H2O, also known by the quaint
name of Glauber's salt. Magnesium sulphate (Epsom salts)
is also quite cheap. The equivalent are as follows:
The Ba2+ in 1.0 gram BaCl2 is all precipitated as
BaSO4 by either:
Sodium sulphate (with 10H2O): 1.6 gm
or Magnesium sulphate (with 7H2O): 1.2 g
Glauber's and Epsom salts are as harmless as you can get.
They are traditional laxatives (tens of grams), so they
may count as slightly more "toxic" than barium sulphate.
Barium chloride sent down the drain will soon end up as
its insoluble sulphate, because sulphate ions are present
in all ground waters. The plants need sulphate to live.
That's why barium chloride isn't dangerous in real terms.
You need to eat or inject a gram or two in order to kill
yourself, and that places it in the same deadliness class
as some compounds of arsenic, mercury etc.
If your safety interrogator asks for a published source
for the safety of throwing out a mixture of your favourite
fixative with some people's favourite purgative, refer him
(or her) to any textbook of chemistry for 14 year-olds
published in the 1950s. That's how I learned the simple
facts about everyday chemicals, together with easy and
non-mathematical explanations. I've forgotten a lot from
those days, but not the simple facts about a dozen
elements and half a dozen rules about how to know the
most important and conspicuous properties of their
> ... We currently mix with Aldex and pour down
> the drain.
The name aldex suggests a neutralizer of aldehydes. Ammonia
does this well, and may be cheaper.
> I don't want to contaminate the ground water ....
There isn't the slightest risk of creating a Ba scare if
everyone involved is somewhere near a high-school chemistry
> .. violating health and safety regulations.
The only legally possible answer is "Look them up."
Intelligently made regulations should not restrict the dumping
anywhere of a substance as harmless as BaSO4. Your lab
amounts will be very much less than those from the bowels
of a patient in a hospital's radiology department.
Nobody has written to Histonet with an explanation of
why BaCl2 should be included in a fixative. That
probably means there isn't one.
John A. Kiernan
Department of Anatomy & Cell Biology
The University of Wester
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