From: styri@hal.nta.no (YuNoHoo)
Subject: Re: UL: Monumental LSD overdose taken (was: Re: Brands of LSD)
Reply-To: styri@nta.no
Organization: Norwegian Telecom Research
Date: Mon, 21 Dec 92 16:24:56 GMT

In article <kNy4VB2w165w@codewks.nacjack.gen.nz>, system@codewks.nacjack.gen.nz (Wayne McDougall) writes:
|> smidt@fy.chalmers.se (Peter Smidt) writes:
|> 
|> > In article <92348.143452U56673@uicvm.uic.edu> U56673@uicvm.uic.edu writes:
|> > >There is a leathal dose of ANYTHING (with the exception of air).
|> > 
|> > Wrong. Air to is lethal. At 80 meters depth divers can be intoxicated
|> > by normal compressed air, because the partial pressure of oxygen
|> > is so high that it starts to make some *very* rapid oxidation of
|> > your nerves and also breaking down the cells. 
|> 
|> Does anyone know who first discovered this fact. [The fact didn't need
|> discovering - it was always there.]

Guess the time is right to straighten out the facts. Now, most of the
following should be the dope found in most decent encyclopedias. I'll
try to be brief...

Air is a mixture of gases. A group of the gases in fairly constant
concentrations, and a group with concentrations that are variable in
space and time. The first mix do vary if you consider extreme variations
in height, but at "ground level" the main gases in the mix is something
like this (numbers are percentage by volume):

	Nitrogen	78.084
	Oxygen		20.946
	Argon		 0.934
	Neon		 0.0018

In addition helium, methane, krypton, krypton, hydrogen, nitrous oxide and
xenon are members of this group. (Well, some may say that methane is not,
but I consider New Zealand a special case.)

In the group of gases with variable concentrations the major gases are:

	Water vapour	0 - 7
	Carbon dioxide	0.01 - 0.1
	Ozone		0 - 0.01

Other members of this group are sulfur dioxide and nitrogen dioxide.

Oxygen was discovered indipendently by C.W. Scheele (apparently 1771,
maybe as early as 1769, but he didn't publish until 1776 i believe)
and J. Priestley (1774). A.-L. Lavoisier contributed to the knowledge
by identifying oxygen as an element and naming the gas.

Nitrogen was discovered at about the same time and the credit usually
goes to D. Rutherford (1772). However, Scheele, and Priestley together
with H. Cavendish discovered it independetly at about the same time.
(Priestley also discovered Dinitrogen Monixide...) Lavoisier identified
nitrogen as an element as well, but he failed to find the correct name
(he named the gas `azote'.) 

Of the above mentioned persons Lavoisier is worth another paragraph. During
the French revolution Marat accused him, among other things, of stopping
the circulation of air in Paris. Some years later, during the Reign of
Terror, he was arrested and May 8 1794 he was tried by the revolutionary
tribunal and guilliotined.

Oxygen is found to be toxic at partial pressure above 0.5 bar if sustained
over some time (days/weeks). A partial pressure of 1.5 to 2 bar may cause
the rapid onset of convultions. However, the limit will vary from person
to person, and the gas mix may have an effect as well. (Michael Jacksons
oxygen tent may not be a good idea, but if he uses a mix of 40% oxygen
and 60% helium he should be able to sleep safe.)

Undir high partial pressure oxigen toxicity manifests itself primarily
in the central nervous system. However, the most frequent symptom reported
in divers who contracted oxygen toxicity was laboured breathing.

Chemically, nitrogen is quite inert. However, it's absorbed by the fatty
tissue (e.g. the brain and the rest of the nervous system) faster than
by other tissues. When a high concentration of nitrogen is breathed the
nervous system becomes saturated with the inert gas, and normal functions
are impaired. The result is nitrogen euphoria or nitrogen narcosis. The
mechanism of nitrogen narcosis is not yet fully understood.

The effect depends on the partial nitrogen pressure, exposure time and
other factors like increased alveolar carbon dioxide amount. Divers can
experience the onset of nitrogen narcosis from 50' to 200', the threshold
varies from person to person. Most often the symptoms becomes apparent
at 100'. It begins as a feeling of light-headedness, euphoria and numbness.
Another description used is carefreeness. The next level is irrationality
and emotional instability. The temperature and light seems to be important
to how the nitrogen narcosis is experienced by the diver. Warm water and
much ligh may give pleasant sensations; Cold, dark water yields anxiety
and panic.

Nitrogen narcosis may be fatal, but usually the victim is capable of
functioning physically (and may not realize that his/her rationality
is impaired.)

Using a nitrogen/oxygen mix diving is limited to about 300' because of
nitrogen narcosis and resistance to breathing. We must use another inert
gas. Helium was found to be superior because it's light and only 1/9 as
narcotic as nitrogen. Hydrogen is another gas used  at extreme pressures.
This option, however, requires the amount of oxygen to be very small. A
side effect when using helium and hydrogen is a Donald Duck'ish voice
that makes communication difficult.

However, I didn't find any references to the person who discovered
the toxic effect of oxygen...

---
YuNoHoo  "why on earth did you want to read this anyway"
Newsgroups: alt.drugs