Chemicals that can cause a severe allergic reaction are classified as:

• A. Irritants
• B. Corrosives
• C. Sensitizers
• D. Toxins

Answer: (C)

The classification of chemicals that can cause severe allergic reactions as sensitizers is rooted in their ability to provoke an immune response upon repeated exposure. Sensitizers are substances that, after an initial exposure, can lead to an allergic reaction upon subsequent exposures. This response occurs when the immune system recognizes these chemicals as harmful, resulting in symptoms such as skin rashes, respiratory issues, or even anaphylactic reactions.

In contrast, irritants primarily cause localized inflammation or irritation of tissues without necessarily triggering an immune response. Corrosives are substances that can cause destruction of living tissue or severe corrosion of material upon contact, which is a different mechanism of action than sensitization. Toxins refer to poisonous substances produced by living organisms, and while they can indeed trigger various biological responses, not all toxins specifically induce allergic reactions.

Thus, the correct classification of chemicals that can lead to severe allergic reactions is sensitizers, emphasizing their unique role in immune system interactions.