Gamma radiation affects living tissues mainly through ionization, which disrupts the normal structure and function of biological molecules — especially DNA. The effects depend on the dose, exposure time, and type of tissue.
1. Mechanism of damage
- Ionization: Gamma photons interact with atoms in cells, knocking out electrons and creating charged particles.
- Free radical formation: Ionized water molecules in cells produce free radicals (e.g., hydroxyl radicals) that chemically attack DNA, proteins, and membranes.
- DNA damage: Breaks in DNA strands lead to mutations, cell malfunction, or cell death.
2. Biological effects
- Cell death: High doses kill rapidly dividing cells (e.g., bone marrow, intestinal lining).
- Mutations: Surviving cells may have altered DNA, increasing cancer risk.
- Radiation sickness: From large, acute exposures (nausea, vomiting, fatigue, hair loss).
- Cancer induction: Long-term risk from even moderate doses.
- Organ failure: Extremely high doses can destroy tissue function (especially in the nervous and digestive systems).
3. Factors influencing severity
- Dose: Higher doses cause more severe effects.
- Exposure duration: Chronic low doses vs. acute high doses have different impacts.
- Tissue sensitivity: Rapidly dividing tissues (bone marrow, skin, reproductive organs) are most vulnerable.
4. Protective measures
- Lead or concrete shielding to block gamma rays.
- Limiting exposure time and increasing distance from the source.
- Monitoring with dosimeters for workers in radiation zones.