A complex approach for the environment health assessment integrating information on contaminants levels registered in environment compartments and bioindication-based estimates is developed and applied to two studies carried out at sites with different scenarios of long-term impact. The environment state is assessed at the territory of a nuclear waste storage facility, Obninsk, Russia, and in the post-mining areas of the Upper Silesia, Poland with enhanced levels of natural radioactivity. Concentrations of micro-, macroelements and appropriate radionuclides activities are measured in samples of water and sediment. With the Allium cepa plant system, phyto- and genotoxicity of the sampled water and soil is estimated to assess a hazardous potential of the complex contamination. As biological endpoints, frequency and spectrum of chromosome aberrations and mitotic abnormalities in ana-telophase cells as well as mitotic activity in Allium cepa root tips are used. An approach and techniques are developed to reveal factors and contamination components that play a governing role in an induction of the observed biological effect and estimate their relative contribution. Compatibility of findings observed and legislative standards adopted are discussed. From the studies carried out, the Allium-test proved to be a sensitive and simple bioassay efficient in genotoxic monitoring of environmental pollutants.