An analysis of the sensitivity of human genetic mechanisms to mutations induced by irradiation and the effect of new mutations on the population in a postattack environment. Increased levels of radiation in the postattack environment will increase the frequency of mutant genes. Based on the concept that most new mutations are harmful, the population could suffer the effects of genetic damage through subsequent generations. An extension of the genetic death concept to the postattack environment indicates that mutant genes harmful to the population will eventually be eliminated. Experimental irradiation of animals shows that the total dose received, the dose rate, and the kinds of cells affected influence the frequency of mutation. Prevention of conception for a period after radiation exposure can reduce genetic damage.