Over the past twenty years or more, there has been increasing interest in the effects of pharmaceuticals in the aquatic environment, particularly in Europe and North America. Thousands of pharmaceuticals are in use worldwide, many are not fully degraded in wastewater treatment plants (WWTPs) and are continuously released in the aquatic environment resulting in concentrations in the low μg l-1 range in the receiving waters. The effects of these drugs, especially at environmentally relevant concentrations, are still unknown. Moreover, few ecotoxicity test species are recommended by Organisation for Economic Co-operation and Development (OECD) and so a dearth of information exists for many organisms.
This study examined the biological effects of prolong low-level exposure of the mixtures of erythromycin, diclofenac, and ibuprofen on the growth, feeding and mortality of aquatic macro-invertebrates ( Gammarus pulex and Asellus aquaticus ). It was found that the mixtures of erythromycin, diclofenac and ibuprofen decreased growth rate, feed intake was reduced but mortality was not significant for both G. pulex and A. aquaticus. The effects of these pharmaceuticals on the growth, feeding and mortality of the test animals were a result of the actions of the drugs and not attributed to a more general stress response. Although pharmaceuticals are indispensable to human health their usage and discharge to the aquatic environment coupled with their ecotoxicity to aquatic life may lead to ecological problems in the near future. Furthermore, this research confirms the suitability of the test species ( G. pulex and A. aquaticus) as ecotoxicological test species that is both amenable to laboratory culture and sufficiently sensitive to provide reliable quantification of environmental risk.