Biological Effects of Radiation
Energy emitted from ionizing radiation has a potentially damaging effect on a wide variety of life. Beginning with the ionization of atoms and resulting in eventual cell damage, radiation may impact many higher-level biological functions. The most critical damage is that which occurs in the DNA of cells. At the molecular level, there are four possible effects that radiation may have on humans.
The first type of effect has no negative consequences for higher-level biological functions. Cells either remain undamaged by the radiation (ionization produces chemical reactions which occur normally in the cell) or cells may be damaged, but not irreparably so. Even damage to chromosomes may occur with few long-term effects because the cell is able to detect and repair limited damage. Even without radiation dosage, changes and repairs in cells, including chromosomes, occur constantly in our bodies.
The second type of effect is more critical and will likely have a negative impact on higher-level biological functions. Cells may be damaged and operate abnormally, or die.
In the third type of effect, damage is done and a cell is unable to completely repair itself. It may function abnormally, as in reproduction. This usually occurs when cells are exposed to lower-dose radiation over an extended period of time (or chronic radiation). It may lead to cancer and genetic effects (problems in offspring), depending on the strength of the dose. Exposure to high-dose, short-term radiation (or acute radiation), may render a cell unable to perform any further function, including reproduction, and it may even die.
On a large enough scale (for example, at the organ level) this kind of damage is likely to cause radiation sickness. Symptoms include skin that seems slightly sunburnt, hair loss, fatigue, internal bleeding, fever, nausea, dehydration and diarrhea, bleeding ulcers, loss of coordination, confusion, coma, convulsions, shock, and more.