The Hazards to Humans section concerning sensitization refers to potential allergic effects.

• A. Chronic
• B. Toxic
• C. Allergic
• D. Acute

Answer: (C)

Sensitization in the Hazards to Humans section is about how some substances can trigger an allergic response. When a person is exposed to a sensitizing chemical, their immune system can become primed so that future exposures provoke an allergic reaction. This can vary from skin irritation or eczema to breathing difficulties, and in severe cases can be life-threatening. The key idea is the immune-mediated, allergic nature of the reaction, not general toxicity or immediate harm.

Chronic refers to long-term health effects from repeated exposure, which is a different concept from sensitization. Acute means immediate effects after a single exposure, which again is not about developing an allergy. Toxic is a broad term for harmful effects from a substance but doesn’t specifically capture the immune allergy aspect that sensitization describes.