If a victim presents with dimness of vision and a runny nose, what type of agent have they likely been exposed to?

Dimness of vision, also known as blurred vision or visual disturbances, combined with a runny nose can indicate exposure to a nerve agent. These agents disrupt the normal functioning of the nervous system by inhibiting acetylcholinesterase, an enzyme necessary for the breakdown of acetylcholine. This interference leads to the accumulation of acetylcholine, resulting in over-stimulation of nerve receptors. One of the symptoms associated with nerve agent exposure can include visual disturbances due to the effect on muscles controlling eye focus and movement.

The presence of a runny nose, or rhinorrhea, can also be a symptom of nerve agent exposure. These agents can cause excessive secretions, including nasal discharge, as the body reacts to the toxic effects of the substances. In contrast, choking agents primarily target the respiratory system and would not typically present with visual disturbances, while cyanide agents affect cellular respiration but do not generally cause these specific symptoms. Biological agents may cause similar symptoms but are usually associated with infections or illnesses presenting over a longer period, rather than acute exposure. Therefore, the combination of dimness of vision and a runny nose points clearly to nerve agents as the most likely cause of exposure.