Safety is the state of being "safe" (from French sauf), the condition of being protected from harm or other non-desirable outcomes. Safety can also refer to the control of recognized hazards in order to achieve an acceptable level of risk.
There must be ever present in our minds the fundamental truth that in a republic such as ours the only safety is to stand neither for nor against any man because he is rich or because he is poor, because he is engaged in one occupation or another, because he works with his brains or because he works with his hands.
Cancer risk in humans exposed to low radiation doses is usually calculated based upon estimates obtained at higher doses. As many cancers originate in stem cells, studying low dose radiation effects on these cells is particularly important.