The method involves preparing an aqueous solution of peracetic acid, where weight percent of the solution includes 0.01 to 5 weight percent of peracetic acid, and 1 to 10 weight percent of hydrogen peroxide. A quantity of acetic acid that is necessary to maintain chemical balance of the aqueous solution is introduced into a package so as to obtain a sterile package containing the aqueous solution of peracetic acid. The sterile package is closed by a vent device. The closed package is exposed to an amount of gamma radiations ranging from 5000-30000 gray, preferably 28000 gray.
