The main thing for the success of the inhabitation of small mammals on the polluted territories is the priority of toxicity for animals or for grassy vegetation of the place their inhabitancy, i. e. direct or mediated influence of pollutants. Primary defeat of animals (direct influence) is feature of radioactive pollution of territory. The inherited adaptation characterised by maintenance of density of population within norm or above (on the background of the lowered migratory activity, frequency increase morphological and physiological infringements etc) develops. Primary defeat of grassy vegetation (pollution SO2, Cu, Cd, Pb, Zn) influences small mammals mediated, secondary, causing reduction of a forage reserve, shelter and reproduction places. Density of population is lowered, migration is increased. Fluoric environmental contamination concerns direct influence, to mediate - pollution by the oil, many heavy metals, some gases (except HF). Probably also the mixed influence, for example, in a near zone of aluminium factories with high concentration fluorine in emissions.