The complex, multifactorial impact of environmental factors on the human being is discussed. The concepts risk detection and risk assessment in environmental hygiene/environmental medicine are defined. For risk detection the special suitability of animal experiments (in vivo tests) as a screening method for the rapid detection of the toxic and oncogenic effects of environmental pollutants are pointed out as well as their supportive role for elucidation of clinical and epidemiological problems and the detection of causal relationships. Beyond that the advantages and disadvantages of the cell culture (in vitro test) are presented and examples of correlations between in vitro and in vivo results are described. For risk assessment, environmental factors, the interior environment as well as problems prospective and retrospective epidemiology are discussed. Finally, the possibilities of the risk assessment are presented and in this connection the determination of geomedically relevant data in order to provide active, effective environmental protection for the exposed population.