Re: VX poison gas

VX nerve gas {methylphosphonothioic acid S-[2-
[bis(1-methylethyl)amino]ethyl] O-ethyl ester} has been around the
media a bit lately because traces of it were allegedly found near a
Sudanese pharmaceutical plant which prompted US forces to bomb it as a
suspected chemical weapons plant.  It was also featured in the movie 'The
Rock' with Nicholas Cage and Sean Connery. Apparently one of Saddam
Hussein's favourite accessories as well.

It is popular with poorer nations and terrorist organisations because it is
relatively easy to make, so long as you have the facilities to contain it.
So in theory you could make it in the backyard, but it would be the last
thing you do!

VX belongs to a family of chemicals known as 'choline esterase inhibitors',
others in this group include Sarin (used in a terrorist attack on the
Tokyo subway), Tabun and the insecticide Parathion.  In a nut-shell these
compounds block enzymes called 'choline esterases' which are involved in
the processes in the brain for communicating nerve impulses.  So VX kills
you by causing respiratory arrest by disrupting your brain's normal
activity which most importantly controls breathing etc.  An effective 
antidote is the muscle stimulant atropine.

For an adult human, the leathal dose of either VX, Sarin or Tabun is less
than 1mg (a single drop of water weighs about 50mg to give you some
perspective).

Most of the above information came from the Merck Index, 12th Edition and 
the text-book 'Biochemistry' 4th Edition by Lubert Stryer.  If you really
want to know about the exact mechanism of action on a molecular level then
any university level Biochemistry text-book should have a section on
'acetyl choline' and 'choline esterase inhibitors' with diagrams

For more information on the web you can go to VX  or Sarin . 

Hope this is of some use.

Dr. Scott Starling
University of Sydney, Australia

Starling@bigpond.com