Which exposure route is the rarest form of exposure?

• A. Inhalation
• B. Ingestion
• C. Injection
• D. Dermal absorption

Answer: (C)

Think about how people usually encounter contaminants in real life. Inhalation is common because we constantly breathe air that can carry dust, fumes, or vapors. Dermal absorption is also frequent since skin comes into contact with many substances during work and daily activities, and some chemicals can permeate the skin. Ingestion happens through eating, drinking, or hand-to-mouth transfer, so it’s another common route. Injection, on the other hand, requires puncturing the skin with a needle or syringe to deliver a substance directly into the body. That scenario doesn’t arise in typical environmental exposure and mostly occurs in medical settings or accidental sharps injuries, making it far rarer overall.