Routes of Internal Exposure

There are four possible routes of internal entry for radioactive materials: inhalation, absorption, ingestion, and injection.

Airborne radioactive materials enter the body usually through inhalation. 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. Absorption through the skin can occur quite rapidly if the skin is cut or scraped. Intact skin is an effective barrier against alpha particles.

Ingestion of radioactive materials occurs when they are swallowed and enter the body through the gastrointestinal tract. Employees can unknowingly ingest harmful chemicals when they eat in areas contaminated by radiation or drink water containing radioactive material.

Injection occurs when a sharp object punctures the skin and deposits radioactive material into the body. For instance, radiation is often injected into cancer patients to kill cancer cells.

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