The main impact area of thermo power plant Šoštanj is Šalek valley (Slovenia). Besides gaseous pollutants also trace elements are emitted into the environment. The research was conducted to study the accumulation of heavy metals in different plant tissues of wild growing medicinal plants (MAP).

The specimens of MAP were collected on eight locations (4-15 km from Šoštanj, 500 - 1000m high). The herb of Hypericum perforatum, Achillea millefolium, Urtica dioica, Thymus serphyllum and Sambus nigra and Tilia plathypyllos flowers were collected, dried and the content of Cd, Pb, As and Hg measured and analysed by atomic absorption spectrometer. The results were compared to legislative values valid in Slovenia and recommended values in EU.

The results indicated that there are no significant differences in heavy metal content between different locations. They were significantly connected to the plant species. The levels of Cd and Pb over recommended doses were recorded in Hypericum perforatum. Other species accumulated Cd and Pb in the following sequence: Achillea millefolium > Thymus serphyllum > Urtica dioica > Tilia plathypyllos > Sambus nigra. The levels of As and Hg were low and comparable in all the specimens. None of these plants accumulated measured heavy metals over allowed limits.