RANKVET: A new ranking method for comparing and prioritizing the environmental risk of veterinary pharmaceuticals

In recent years veterinary medicinal products (VMPs) have been recognized as emerging contaminants, giving rise to concerns regarding their environmental impact. Due to the high number of utilized VMPs, it is necessary to develop tools (indicators) for ranking these compounds according to their environmental risk relevance. These indicators can be useful, for example, for setting up monitoring programmes, and more in general for risk management purposes. In this paper we propose a new scoring system method (RANKVET) that enables ranking the risk of VMPs for aquatic and terrestrial organisms. The procedure is fully based on the information required by the EU Directives and Regulations for marketing authorization of VMPs and Veterinary International Conference on Harmonization (VICH) guidelines. According to the latter, if the environmental risk assessment of a VMP indicates an unacceptable risk to the environment, i.e., the risk quotient (RQ) consisting of the ratio of Predicted Environmental Concentration (PEC) to Predicted No Effect Concentration (PNEC) is ≥1, then mitigation measures should be proposed by the applicant in order to reduce the risk to an acceptable level. If a risk mitigation measure does not fulfil the criteria mentioned above then the outcome of the risk assessment is that a serious risk for the environment exists. In accordance with Directive 2001/82/EC (as amended) this risk has to be weighed against the favourable aspects of a marketing authorization. The prioritization scheme is based on a quantitative approach and consist of different phases. First, for each VMP, PECs are calculated using simple exposure models and worst case assumptions. PNECs are calculated for non-target organisms representative of the considered ecosystems (soil or surface water). Then numerical scores are given to the calculated PEC/PNEC ratio. Finally, the obtained score is multiplied with a further score which is based on the relevance of the metabolic rate in animals. RANKVET can be applied for surface water and soil systems and for different farming methods (intensive or pasture) and treated species. As an example of its potential use we applied RANKVET to 48 VMPs largely utilized in Italy.