Environmental risk assessment of antibiotic residues in cattle slurry used as fertiliser

The aim of the study was to assess the environmental risk caused by active antibiotic substances present in cattle slurry from ecological farms, used for fertilisation purposes. In order to assess the environmental risk, studies were carried out on farms located in the cleanest region of north-eastern Poland. The study focused on substances most commonly found in veterinary drugs: tetracycline, bacitracin, kanamycin, dihydrostreptomycin, benzylpenicillin, cefquinome, and cephalexin. In the analysed cattle slurry, only tetracycline, benzylpenicillin, and cephalexin were detected in the analysed slurry. Their concentrations were respectively 1.53–15.1, 0.048–0.27, and nd–1.11 ng∙g−1. Other tested antibiotics, such as cefquinome and dihydrostreptomycin, were detected in the samples of cattle slurry at concentrations below the LOQ. Bacitracin and kanamycin were not detected in any of the samples. The environmental risk assessment, based on the risk quotient (RQ) values calculated for tetracycline and benzylpenicillin, indicated that the potential risk to soil was well below the level of concern (LoC). The risk assessment for cephalexin could not be performed due to the lack of sufficient data. The analysis indicates that the risk to the soil compartment from the application of cattle slurry originating from organic farms is below the level of concern. However, due to data gaps in the available literature, a comprehensive analysis could not be completed.