At the molecular level, radiation can cause ionisation in tissue, damaging biological molecules. The strands of DNA are held together by hydrogen bonds, which are very weak and easily broken. Ionisation in the surrounding medium – the cytoplasm in the cell - where chemical reactions called metabolic pathways take place, can interfere with those reactions.
Molecular damage caused by radiation can cause the cell to die, to stop dividing and multiplying. Cells die all the time and are removed by the body as part of a natural process. Too large a dose of radiation can cause radiation sickness. People can recover from this, but there is also the possibility, even for small radiation doses, of mutations in DNA causing cells to multiply out of control – cancer.
There is no such thing as a safe dose of radiation. All exposure to radiation should be minimized. Every x – ray taken should have a medical justification, and people living in areas where radioactive radon gas seeps out of the rocks should keep their houses well ventilated so the gas does not collect there.
People most ignorant of radiation can take obvious steps to minimise danger.
Keep your distance from a source.andradiation both have quite short rangers, so unless the source is in the atmosphere and can be breathed in, these sources of radiation are not very dangerous.radiation has a longer range but is less harmful. It obeys an inverse square law, becoming less intense with distance from the source, so the dose can also be minimised by increasing distance.
Hide behind a screen. A lead screen will shield you fromrays.
Less obviously, people who ingest radiation are often given milk to drink as this can speed up the removal of some isotopes from the body. If an atom bomb explodes in your neighbourhood, fill the bath with water and hide inside it. Water absorbs radiation quite well, and has a high heat capacity so the energy released by the bomb may not heat it that much if the explosion is not close. In addition, a metal bath will provide some shielding from therays.