Naproxen in the Environment

Active pharmaceuticals ingredients (APIs) are necessary for the wellness and health of humans and animals. Nevertheless, because they have biological activity also on non-target organisms, they might cause environmental side effects worth to be considered. In fact, during the last 25 years the occurrence of APIs in natural environments such as surface water, groundwater, soil, etc. has been increasingly reported in the scientific literature. As a consequence, these molecules are included in the category of the "contaminants of emerging concern", which encompasses contaminants that can be detected at low (µg-ng) concentrations but whose effects on the environment are not well defined. Despite the potential for harmful ecological and human health effects these emerging contaminants are not covered by the current law for the quality of surface or ground waters, and an urgent need for scientific sound information is necessary for the assessment of their environmental risk. The nonsteroidal anti-inflammatory drug Naproxen is a polar compound that has been detected in concentrations ranging from ng to µg per litre in surface waters and in wastewater treatment plant effluents. This pharmaceutical is absorbed by the organism after intake and is subject to metabolic transformations. However, a significant fraction of the original substance is excreted un-metabolized by the human organism via urine or faeces and is thus emitted in its active form into raw sewage and sewage sludge. The presence of Naproxen in surface water is due to its incomplete removal in WWTPs or the direct discharge of untreated wastewaters into rivers. This API has resulted ready biodegradable in aerobic conditions, but owing to its large human consumption it is continuously discharge in large concentrations which leads to the phenomenon known as pseudo-persistency and its occurrence at concentrations higher than other more persistent APIs. This aspect is important in the light of the recently found evidence of possible detrimental effects on natural bacterial populations at realistic concentrations, which cannot exclude negative effects on bacteria key for the ecosystem functioning. In this chapter the occurrence of Naproxen in different aquatic environments, its environmental fate and the typical pseudo-persistency, as well as its effects on different ecosystems will be discussed.