Determination of the Toxicity of Water Contaminated with Pharmaceutical Preparations by Biotesting Methods

Abstract

This study justifies the use of biotesting methods to assess the level of toxicity in aquatic environments contaminated with pharmaceutical substances (PSs) of various origins, including diclofenac, streptocide, and paracetamol. To determine overall toxicity, we used Daphnia magna, a cladoceran crustacean, and Brachydanio rerio, a representative vertebrate aquatic organism. To assess cytotoxicity, the blood cells of zebrafish were tested. The biotesting results showed that the tested pharmaceuticals exerted varying degrees of toxicity on aquatic organisms, depending on their concentration in the water, and caused pathological changes in fish blood cells. Aqueous solutions of the pharmaceuticals at concentrations from 0.1 to 10.0 mg/dm³ caused acute toxic effects in Daphnia and chronic toxic effects in fish. In addition, cytotoxicity in the blood cells of Brachydanio rerio was detected after 10 days of exposure to the studied compounds, well before the onset of mortality in the test organisms. According to the European Directive EC 93/67/EEC, these effects correspond to “very toxic,” “toxic,” and “harmful” classifications for aquatic life. These findings indicate negative trends in the ecological status of natural water bodies that are continuously polluted by pharmaceuticals and their metabolites. Excessive contamination may lead to irreversible degradation of aquatic ecosystems.