maturity, and to maintain our health. Billions of cells in our bodies are constantly "dividing" or making exact copies of themselves to produce new cells. Basic to this copying process is the chromosome, which insures that each new cell of its kind is an exact copy. If it is not, it may die, or it may produce an altered form of the cell which is not useful, or possibly harmful, to the other cells and ultimately the body. Perhaps trillions of these divisions, or duplications, go on in our body during our lifetime -- and despite the near perfect accuracy with which it is usually done -- sometimes there are "mistakes" made, or defects. ''Breaks" may occur during the division and one cell may end up with an imperfect chromosome. This cell may be unable to duplicate itself and die, or may duplicate the new defective form. While these abnormal cells may be produced normally through "mistakes," they may also be produced by ionizing radiation. Gamma and beta rays, neutrons, and alpha particles passing through the atomic structures of the DNA chemicals can distrupt their physical structures. The chemical changes that can be made by these electrons and other particles can cause defects in the DNA and genes, and in turn the chromosome, and thus the cell. In large doses, these effects to cell duplication are easily seen. Damage by gamma particles to the cells which line the small intestine cause nausea, vomiting, and diarrhea. Beta damage to the skin and hair . results in skin burns and partial or complete loss of hair (epilation). The long term effect of doses which do not prove fatal, and of low doses, is another matter. Long Term Effects So far we have seen how man can be exposed to radiation and what acute effects he can suffer, ranging from mild itching and burning of the skin to convulsions and a miserable death. mee ois These effects are