Internal contamination results when radioactive material is taken into the body via inhalation or ingestion or open wounds.
Internal deposition of radioisotopes in organs results in local exposure at that location.
Internal contamination continues until the radioactive material decays, is flushed from the body by natural processes, or is removed by medical countermeasures.
Types of internal contamination
Via respiratory tract: When aerosol particles are inhaled, those measuring <5 micrometers can reach the alveoli, whereas larger particles will remain in proximal airways.
Tiny particles can be absorbed by the lymphatic system or the blood stream, or continue to irradiate locally until exhaled, removed, or depleted of their radioactivity.
Via digestive tract: If swallowed, soluble radionuclides may be absorbed in the upper tract, whereas insoluble radioactive particles may affect the lower gastrointestinal (GI) tract. Depending on the specific radioisotope, particles in the GI tract may be lavaged, expelled, and/or removed using drugs.
Via radioactive dust in open wounds: Small radioactive particles in open wounds may be absorbed into the body via blood or lymphatic channels.
How to diagnose
If after external decontamination, an appropriate radiation survey meter continues to identify significant residual radioactivity, suspect internal contamination.