Algorithm of calculation of predicted concentration (PEC) for evaluation of the environmental risk of veterinary medicinal products

The environmental risk analysis for veterinary medicinal products is an assessment of their possible evolution, exposures and effects and is structured according to the VICH GL6 (Phase I) and GL38 (Phase II) guides. The environmental risk assessment, an integral part of the veterinary medicinal product authorizations, interpreted and harmonized under the VICH guidelines, ensures the predictability and transparency of the results obtained. The route of distribution and the evolution in the environment are important factors for the concentration of the final exposure. The risk quotient (RQ) is defined as the ratio between the predicted environmental concentration (PEC) and the predicted no-effect concentration (PNEC). The risk quotients indicate the likelihood of adverse effects occurring. For the determination of PECs, soil, water, sediment, environmental exposure for the product, its active substances and other ingredients is considered, taking into account target species, mode of administration, and physicochemical characteristics. Calculation of the predicted active substance concentration in the soil (PECsol) is based on the total residue approach. The calculation of the concentration of the active substance in groundwater (PECgroundwater) is based on the solid sorption equilibrium approach, modeled by the organic water-carbon distribution coefficient (Koc). The predicted concentration of the active substance in surface water (PEC surface water) is considered to be 1/3 of the groundwater concentration and in the sediment is calculated according to the sediment-water partition coefficient (Ksed-water). The paper presents an algorithm for calculating predictable concentrations for environmental factors: soil, water, sediment required for environmental risk assessment of veterinary medicinal products. Based on this calculation algorithm, a specialized interactive software has been developed to allow rapid and convenient determination of predictable PEC concentrations for environmental factors: soil, water, sediment for veterinary medicinal products. It is a very useful tool for environmental risk assessment specialists.