Which of the following routes of exposure includes breathing in chemicals?

• A. Ingestion
• B. Injection
• C. Absorption
• D. Inhalation

Answer: (D)

Inhalation is the route of exposure that involves breathing in chemicals. This can occur when vapors, gases, or particles are dispersed in the air and then enter the respiratory system through the mouth or nose. Inhalation is particularly concerning because it allows for rapid absorption of hazardous substances into the bloodstream via the lungs due to their large surface area and rich blood supply.

Understanding the inhalation route is critical for identifying potential health risks in environments where chemical exposure is possible, as it can lead to immediate and serious health effects depending on the nature and concentration of the inhaled substances. The other routes of exposure—ingestion, injection, and absorption—represent different mechanisms through which a chemical can enter the body, but they do not involve breathing in the substances, which is why they are not applicable to this question.