Routes of Entry

The health risk of a chemical or toxin is affected by its route of entry into an individual's body. There are four possible routes of entry: inhalation, absorption, ingestion, and injection.

Inhalation is the primary route of entry for hazardous chemicals in the work environment. Nearly all materials that are airborne can be inhaled. When air is drawn in through the mouth and nose, it reaches the lungs, where contaminants can cause scar tissue or be dissolved in the blood and transported through the rest of the body.

Absorption through the skin is another route of entry. The skin is the largest organ of the body and a common exposure site for liquid and airborne chemicals. Absorption through the skin can occur quite rapidly if the skin is cut or scraped. Intact skin is an effective barrier to many hazardous materials.

Ingestion of toxic materials occurs when they are swallowed and enter the body through the gastrointestinal tract. In the workplace, employees can unknowingly ingest harmful chemicals when they eat, drink, or smoke in contaminated work areas.

Injection occurs when a sharp object punctures the skin, allowing a chemical to enter the body. For example, injection can occur when a contaminated object such as a metal filing punctures the skin.

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