Chap. 13. Terrorism, Toxicity, and Vulnerability 335consequence of the binding of the receptor to the toxicant there is a biochemical effect.
A common example of a biochemical effect occurs when a toxicant binds to an enzyme
such that the bound enzyme may be inhibited from carrying out its normal function. As
a result of a biochemical effect, there is a response, such as a behavioral or physiological
response, which constitutes the actual observed toxic effect. Acetylcholinesterase enzyme
inhibited by binding to nerve gas Sarin may fail to stop nerve impulses in breathing
processes, leading to asphyxiation. The phenomena just described occur in the dynamic
phase of toxicant action as summarized in Figure 13.3.
ToxicantReceptorToxicant-bound
receptorAbnormal biochemical
effect- Enzyme inhibition
- Biosynthesis disruption
- Disruption of O 2 utilization
• Cell membrane disruption
Physiological or behavioral response
manifesting toxicity- Central nervous system effects including
convulsions, paralysis, hallucination,
coma, ataxia (loss of muscle coordination) - Abnormalities in vital signs of pulse rate,
respiratory rate, blood pressure, temperature - Mutagenesis
- Carcinogenesis
- Damage to immune system
Figure 13.3. The dynamic phase of toxicity in which a toxicant interacts with a receptor in the body to
cause a biochemical alteration that is manifested in a toxic response.
13.5. Toxic Chemical Attack
Bhopal
The tragedy that arguably illustrates most vividly the potential of chemicals to
kill many people was the accidental release of methyl isocyanate from a chemical
manufacturing operation in Bhopal, India, during the night of December 2/3, 1984,
exposing many victims as they slept in their homes. About 40 tons of this chemical was
released during the incident exposing thousands of residents in the surrounding area. Of
those exposed, more than 3000 died, primarily from pulmonary edema (fluid accumulation