| Popis: |
For many years now, pharmaceuticals and pesticides are frequently detected in the aquatic environment and in that context are defined as contaminants of emerging concern. Recently, a lot of concern has grown around the joint toxic effects of such compounds due to the fact that information on this emerging issue are still scarce [1, 2]. Such efforts are recognized by EU Commission providing an opinion on the importance of gaining such information [3]. For the purpose of investigation and acquiring new insights within the current study three pharmaceuticals: ciprofloxacin (CIP), carbamazepine (CBZ), diclofenac (DCF) and three pesticides: alachlor (ALA), atrazine (ATZ), and simazine (SMZ) were selected in order to analyze their combined toxicity in binary mixtures. Overall, 6 single component and 18 binary mixtures toxicities were determined using green microalgae Pseudokirchneriella subcapitata (Selenastrum capricornutum) according to standard procedure (ISO). For the description of mixture toxicities, two common mathematical models were applied: concentration addition (CA) and independent action (IA) model. Binary mixtures of pharmaceuticals indicated synergism, while mixtures that contained CBZ and CIP exhibited antagonistic behavior with the respect to the additive behavior (CA model). On the other hand, mixtures of pesticides were acting very similarly ; the synergism with respect to additive behavior was observed for most combinations. The applicability of IA model as a proof of independent toxic action of the components was not confirmed in any case. Thus, CA model showed to be adequate to predict and describe the possible interactions occurring between pharmaceuticals as well as pesticides mixture, since all investigated compounds have a similar mode of action. On the term of the obtained results, we can conclude that assessing the ecological risk based only on the effects of individual pharmaceuticals or pesticides can underestimate the risk level posed by a mixture of these environmental contaminants. |
