In this paper the use of animals in organic litter and in the mineral part of soils as bioindicators of ionizing radiation is reviewed. Soil animals are the most suitable biological indicators of radioactive pollution because they are parts of nutritional chains and webs, occur in relatively high numbers and can be collected during most parts of the year. Insects and other forest-dwelling invertebrates are more resistant to radioactive pollution than vertebrates, probably because of the shielding effects of soil constituents. In experiments with 90Sr, 137Cs, 106Ru, 95Zr, 65Zn 125Sb and 239Pu on different components of the mesofauna, earthworms (Oligochaeta) and Myriapoda (Diplopoda and Chilopoda) were affected most intensively, probably because these organisms have an intimate inside and outside contact with soil constituents in the upper layers of the soils. Soil dwellers that are only transitorily in soil or characterized by rapid distribution (predatory Coleoptera, flying insects) are less affected by radiation. Under natural conditions, the doses of irradiation of animals in the upper forest layers are lower than those of dwellers within soil. Forest insects that hibernate in soils at the egg or larval stage are most intensively affected and reduced by radiation. Earthworms prove particularly sensitive to an increased Ra-radiation background. They are among the best bioindicators of polluted soils.
Soil faunaIonizing radiation effectsPermanent and temporary soil dwellersRadioactive pollution EdaphonEarthwormsBioindicators