Which exposure route involves direct penetration through a cut or abrasion?

The exposure route that involves direct penetration through a cut or abrasion is injection. This route refers to substances entering the body through breaks in the skin, such as cuts, abrasions, or needle sticks. When a hazardous material or toxin is injected through these openings, it can bypass the body's natural barriers, allowing for rapid systemic absorption and potentially leading to significant health effects.

In contrast, absorption involves the uptake of substances through intact skin, while ingestion pertains to substances being taken into the body through the oral cavity. Respiratory exposure involves inhaling agents through the nose or mouth, which is a different mechanism altogether. Understanding the distinction between these routes of entry is crucial for evaluating potential hazards and determining the appropriate response methods during HazMat incidents.