Which statement best describes primary irritants?

• A. They exert little systemic toxic action or react on contact
• B. They cause immune sensitization only after repeated exposure
• C. They primarily irritate mucous membranes
• D. They are the same as asphyxiants

Answer: (A)

Primary irritants cause damage where they touch, producing local irritation with little or no systemic toxicity. They don’t rely on the immune system to produce a reaction, so prior exposure isn’t required for irritation to occur. This is why the best description is that they exert little systemic toxic action or react on contact.

Sensitizers, by contrast, provoke an immune response after repeated exposure, which is a different mechanism from the immediate local irritation of primary irritants. While irritants can affect mucous membranes, that effect isn’t the defining feature of primary irritants. Asphyxiants relate to substances that disturb oxygen delivery, not to the irritant action itself.