Radiation-Induced Damage May Require Threshold Dose

A radiation dose is known to cause damage to biologic systems, and the type of damage can be classified as either deterministic or stochastic. Deterministic Effects: Deterministic effects are characterized by having a dose threshold, and the severity of the effect increases with increasing radiation dose above that threshold. Examples of deterministic effects include erythema, epilation, radiation syndrome, sterility, etc. Each of these effects starts out in a mild form and gets increasingly worse as the radiation dose to the individual increases. Stochastic Effects: Stochastic effects are probabilistic -- the risk of the effect increases with radiation dose, but the effect itself is the same and it is an all-or-nothing effect. Stochastic effects include radiation-induced cancer and genetic effects. The genetic effects of radiation have been observed in animal investigations, but we have not seen this in humans because no experiment can ethically be done where we expose enough people more...