Lichens, sampled around Chernobyl in 1990 and in Slovenia in 1992, were analyzed for radionuclides and elements, including Cs. Data were processed by Monte Carlo aided Target Transformation Factor (MCTTFA). The resulting factors indicate environmental accumulation routes. 40K : K and 210Pb : Pb ratios tested the procedure, showing fully mixed 40K and K, while for 210Pb and Pb the expected variability in specific radioactivity was confirmed. 137Cs showed a large factor-specific variability in 137Cs : Cs ratios. For the 1990 data, MCTTFA singled-out 137Cs in a separate factor, suggesting that the overall behavior of 137Cs cannot be derived from that of Cs: source (route)-related specific radioactivity makes that all individual transport-components should be taken into account.