Green Chemistry and the Ten Commandments

Chap. 13. Terrorism, Toxicity, and Vulnerability 339

respiratory system. The binding of diisopropylphosphorfluoridate to a serine side-chain
on the active site of acetylcholinesterase enzyme is shown by the reaction below:

Inhibited   enzyme

+

H

3

N C C N

H HC

OH

H H O

N C C N

H H O

H C H

H

H 3 C C CH 3

O

H

CH 3

CH 3

C O P O

Serine  side-chain  on

enzyme  active  site

C O P O

CH 3

CH 3

H

O

H 3 C C CH

F

Diisopropylphospho-

fluoridate

(13.5.2)

Biotoxins

Some of the most toxic substances known are produced by organisms and some of
these have been used to attack humans. Clostridium botulinum bacteria growing in the
absence of oxygen produce botulinum toxin, which has killed many people who have
eaten improperly canned food (heating to 80–100 ̊ C for a sufficient time deactivates
the toxin). Consisting of several proteins, botulinum toxin binds irreversibly to nerve
terminals preventing the release of acetylcholine, an enzyme required for proper nerve
function. Neurologic symptoms are followed by paralysis of the respiratory muscles and
death. From the LD 50 of about 1 × 10-^5 mg/kg for botulinum toxin shown in Figure 13.1,
it may be inferred that a 70 kg person could die from absorbing only 0.0007 mg (only
about 1 microgram) of this extraordinarily deadly substance. Millions of people could
be killed by the amount of this toxin that could be carried in a terrorist’s pocket if some
efficient means could be found to deliver it.
Ricin, a protein extracted from castor beans (Ricinus communis), is another highly
toxic natural product. Only about 1/2 milligram of ricin (about the size of a pinhead) can
be fatal when injected resulting in failure of kidneys, liver, and spleen along with massive
blood loss from the digestive tract. Ricin gained notoriety in the 1978 assassination in
London of the Bulgarian writer and journalist Georgi Markov injected with ricin from
the tip of an umbrella. Although it is mentioned as a potential terrorist tool, ricin has its
greatest toxicity by injection, which tends to limit its use as a weapon.

13.6. Protecting Water, Food, and Air

Water to drink, food to eat, and air to breathe — the most basic of human needs —
are likely targets for terrorist attack. The finding of a single cow with mad cow disease