Which statement best describes the relationship between irritants and sensitizers?

• A. Irritants generally cause local inflammation, while sensitizers can trigger immune responses with repeated exposure
• B. Irritants and sensitizers are the same
• C. Sensitizers always cause immediate toxicity
• D. Irritants never cause inflammation

Answer: (A)

Irritants cause local inflammation through direct chemical irritation of tissues, and this response does not depend on prior exposure or immune memory. Sensitizers, in contrast, set off an adaptive immune reaction after the body has become sensitized to them; on subsequent exposures, T cells recognize the substance and mediate an immune response, often as a delayed hypersensitivity reaction such as allergic contact dermatitis. This means sensitizers require repeated exposure to produce a reaction, whereas irritants can provoke inflammation the first time and with ongoing exposure. The other statements don’t fit because irritants and sensitizers are not the same; sensitizers do not always cause immediate toxicity and irritants can certainly cause inflammation.