Chapter 17 · Radioactivity and Nuclear Chemistry
17.10The Effects of Radiation on Life
9 min · two checks
Predict
Why is ionizing radiation dangerous to cells?
The idea
- Describe ionization damage.
- Distinguish acute dose from increased long-term risk.
Alpha, beta, gamma, X-rays, and neutrons are ionizing: they carry enough energy to eject electrons from atoms. The broken molecules include water, which forms reactive fragments, and DNA, which can be cut or mis-copied. Cells repair a lot of this. What they fail to repair can kill the cell or, worse for the organism, let it survive with damaged growth controls.
A large dose in a short time causes acute radiation sickness: damage to the gut lining, bone marrow, and other fast-dividing tissues. Smaller doses do not produce that immediate illness but increase the probability of cancer years later. Genetic damage is damage to DNA in cells that can be passed on, as distinct from illness in the exposed person. Dose depends on energy deposited per kilogram, on the radiation type — alpha is especially damaging if it is inside the body — and on time. Distance, shielding, and limiting time are the practical protections. Natural background is a baseline, not a reason to ignore an added source.
Keep these
- Ionizing radiation breaks molecules, including DNA.
- Acute sickness and later cancer risk are different consequences.
- Time, distance, and shielding reduce dose.