One of the most dangerous sources of environmental pollution, including medicinal plants, is radionuclides. Chernobyl NPP accident has caused a number of new problems related to the lack of systemic information on the radioactivity level of medicinal plants and especially of herbal products (a risk factor for human health).
Most dangerous are radionuclides with long half-life — Т1/2 (e.g., Т1/2 for 137Cs and 90Sr — several dozens of years). Radionuclide half-life Т1/2 is a period, when the amount of radioactive atoms of a substance halves.
Radionuclides can get into plants from the atmosphere, soil or water. The degree of retention on plants and penetration into plants depends on biomass, foliage, habitat, etc. Secondary aerial pollution (radioactive dust transport by wind) is of great significance.
The rate of radionuclide passage from plant materials to a drug is very wide; e.g., for Cs-137, this value in wild rose and plantain decoction is 70%; lily-of-the-valley infusion has the lowest value.
Temporarily acceptable level for Cs-137 in plant drugs is 1.5×10–8 ku/kg.
Once in the body, radionuclides accumulate in muscles (Cs-137) and bones (Cs-90) and are sources of constant radiation, potentially causing radiation sickness.
The rate of plant’s exposure to ionization radiation can be enhanced by presence of bad impurities in the environment: nitrogen and carbon oxides, ions of heavy metals, pesticides, etc. In turn, radiation facilitates accumulation of toxic substances in plants: heavy metals, nitrates, etc., (the so-called radioecological synergism). For instance, lead concentration in hedge plants exposed to ionization radiation can increase 50-fold.
In a number of regions that were exposed to radiation contamination, MAC for nitrates exceeds the normal value manifold. Concentration of various pesticides in the environment is extremely high as well.