Which nerve agent is not typically liquid at room temperature due to its high volatility?

Nerve Agents: Physical Properties and Identification

Sarin (C) is the correct answer - it is the only nerve agent among the options that is not typically liquid at room temperature due to its high volatility.

Physical Properties of Nerve Agents

Nerve agents are highly toxic organophosphorus compounds that inhibit acetylcholinesterase activity within the central, peripheral, and autonomic nervous systems 1. They can be categorized based on their physical properties, particularly their state at room temperature:

Liquid Nerve Agents at Room Temperature:

• Tabun (GA): Liquid at room temperature with a fruity odor
• VX: Oily liquid with very low volatility, persistent in the environment
• Soman (GD): Liquid with a fruity/camphor odor
• Cyclosarin (GF): Liquid with higher persistence than other G-agents

Volatile Nerve Agent:

• Sarin (GB): Highly volatile liquid that quickly evaporates to gas at room temperature 2

Comparative Volatility and Persistence

Sarin has the highest volatility among the listed agents, making it primarily present as a vapor at room temperature rather than a stable liquid 2. This property makes it particularly dangerous for inhalation exposure but less persistent in the environment compared to the other agents.

The physical properties directly impact:

• Route of exposure (inhalation vs. dermal)
• Persistence in the environment
• Decontamination requirements
• Personal protective equipment needs

Clinical Implications of Nerve Agent Exposure

All nerve agents cause a cholinergic crisis by inhibiting acetylcholinesterase, leading to:

1. Muscarinic effects: Miosis, copious secretions from respiratory and GI tracts 3
2. Nicotinic effects: Muscle weakness and twitches in severely affected victims 3
3. Central nervous system effects: Seizures, altered consciousness, respiratory depression 4

Special Considerations for Children

Children may present differently than adults when exposed to nerve agents:

• Less likely to manifest miosis and glandular secretions
• May present with neurologic derangements alone 4

Treatment Approach

Treatment for nerve agent exposure includes:

1. Decontamination: Remove clothing and wash skin with soap and water
2. Antidotes:
   • Anticholinergics (atropine)
   • Oximes (pralidoxime)
   • Anticonvulsants (diazepam, midazolam) 4

Key Points for Identification

When identifying nerve agents in an emergency situation:

• Sarin will rapidly evaporate and primarily present as a vapor hazard
• VX is the most persistent and least volatile
• Tabun, Soman, and Cyclosarin maintain liquid form at room temperature with varying degrees of volatility

Understanding these physical properties is crucial for proper risk assessment, decontamination procedures, and medical management of exposed individuals.