The aim of the paper was to determine benz(a)-pyrene in the preparations containing humates and study the benz(a)pyrene biological potency for the agricultural plants. The research methodology included the determination of the dependencies in the system “substance concentration (dose)—effect on the plant”. Concentrations of benz(a)pyrene in 12 samples of the humates preparations and fertilizers based on their trademarks “Irkutsk humates”, obtained from brown coal, varied in the range from 0.3 to 50 mcg/kg, which creates no soil contamination in conditions of the use of preparations. Between contents of benz(a)pyrene and humates there is a correlation (rxy = 0.95; α = 0.05). It is ascertained that the effects of stimulation and/or inhibition of the growth and yield of agricultural plants depend on the concentration of benz(a)pyrene and the method of plant processing. Optimal concentrations of benz(a)pyrene were 150-200 ng/dm3 for preplant way of processing of potato tubers, 3-10 ng/dm3—for top dressing (spraying) and 0.1-0.3 ng/dm3—for dressing under the roots (hydroponic). The obtained results allowed us to offer one of the possible mechanisms of biological potency of humates as the plant growth stimulants, and also a way testing of the preparations by screening of their benz(a)pyrene content.
 Sanitary Norms and Regulations 184.108.40.2060-96 (1997) Sanitary demands on the quality and safety of the food raw material and food. Food stock and products. State Committee on Sanitary and Epidemiology Surveillance (SCSES) of Russia, Moscow.
 Belykh, L.I. and Ryabchikova, I.A. (2008) The methodology of defining the mass concentration of benz(a)pyrene in the trials of vegetable materials using the method of low-temperature luminescence. The certificate of assessment MVI No 224.11.04.019/2008. The Ural Institute of Metrology Publ., Ekaterinburg.
 Belykh, L.I., Ryabchikova, I.A., Dodonova, N.E. and Timofeyeva, S.S. (2009) The method of biological potency identification and testing of humates containing preparations and/or fertilizers on their basis and the method of plants biochemical activity increasing (options). Patent No. 2375335 RF, MPK С05F 11/00.