Final Answer:
The most common route of entry through which hazardous materials are introduced into the body is inhalation.
Step-by-step explanation:
Inhalation, or the act of breathing in contaminated air, is the most common route of entry for hazardous materials into the body. When individuals inhale air containing toxic substances, these materials can be absorbed by the respiratory system and enter the bloodstream, leading to systemic exposure. Airborne hazardous materials, such as gases, vapors, or particulate matter, can be particularly dangerous as they can easily be inhaled.
Other routes of entry for hazardous materials include ingestion (swallowing) and dermal contact (through the skin). However, inhalation is often considered the most direct and immediate pathway for toxic substances to affect the body, making respiratory protection measures critical in environments where hazardous materials are present.