Avaliação do risco ecotoxicológico individual e da mistura de fármacos detectados em ambientes aquáticos

Abstract

The occurrence of pharmaceuticals in aquatic environments and in water for human consumption has worried the scientific community in relation to possible effects on the environment and public health. Despite that, consistent ecotoxicological data for these compounds are still scarce, mainly related to chronic effects. Additionally, most studies are focused on evaluating the individual risk of compounds and, only recently, efforts to assess the effects of the combination of these drugs on non-target organisms have been observed. For these reasons, the objective of this theses was to evaluate and model the individual ecotoxicological risk and the mixture of pharmaceuticals frequently detected in aquatic environments. In order to facilitate data appreciation, the thesis is developed in chapters. Thus, the development of chapters 2 and 3 consists of selecting, through a through a preliminary assessment of the ecotoxicological risk and human health of the drugs detected in the Metropolitan Region of Belo Horizonte (RMBH), five drugs which had their toxicity tested. In chapter IV, the selected drugs – atorvastatin, betamethasone valerate, loratadine, fenofibrate and prednisone – were submitted to acute and chronic toxicity tests using the organism Ceriodaphnia dubia. Additionally, the possible binary mixtures of pharmaceutical compounds had their acute toxicity tested, in order to evaluate the predictability of the Concentration Addition models and Independent Action, in addition to evaluating the possible interactions in binary mixtures using the Combination Index model. It also aimed to assess possible synergic and antagonistic effects. The other chapters intend to respectively introduce and close the thesis with an integrative approach. The results indicate a potential risk to aquatic organisms and human health from the exposure to pharmaceuticals detected in the Brazilian aquatic environments. The pharmaceuticals identified by the applied prioritization methodology (atorvastatin, fenofibrate, loratadine, betamethasone, clarithromycin, fluconazole, prednisone and gemfibrozil) accounted for more than 75% of the ecotoxicological risk of the mixture in most of the evaluated scenarios, indicating the applicability of these methodologies for the management of risk. Regarding the acute toxicity tests, the most toxic pharmaceutical was loratadine (2.33 mg/L) and, in the chronic toxicity tests, the most toxic drug was fenofibrate (0.16 mg/L). The test results with the binary mixtures allowed us to conclude that the concentration addition and independent action models were not adequate to predict the toxicity of the mixture, especially at low concentrations. The combination index model has proved to be a useful tool to describe the nature of toxicological interactions that occur between drugs. Even concentrations where no effect was observed in the trials with the drugs alone, caused adverse effects when in mixtures (something from nothing). It was concluded that the ecotoxicological risk assessment based on the individual concentration of pharmaceuticals may underestimate the real impact of these compounds on aquatic ecosystems. Tests with the mixture of pharmaceuticals at environmentally relevant concentrations suggest that adverse effects on survival and reproduction of C. dubia are not induced at concentrations where these pharmaceuticals are detected in aquatic environments.