Pharmaceuticals in urban streams: a review of their detection and effects in the ecosystem

The presence of pharmaceuticals in urban freshwater has been considered an emerging issue. Although rivers are better studied, the streams crossing the cities, which are prone to higher concentrations of pharmaceuticals, and with a higher potential to affect animals, plant and human health, were never specifically addressed in a review. Thus, here we performed a literature review on the existing pharmaceutical contamination and impacts of these compounds in the urban stream ecosystems. To structure the review, 10 questions were designed. From a total of 206 scientific publications, only 51 addressed the issue of pharmaceuticals in urban streams compared to 180 studies in the larger urban rivers. In 49 urban streams located in 13 countries and four continents, 139 pharmaceuticals from ten therapeutic groups were found. Anti-inflammatories and anticonvulsants were detected in the largest number of countries and urban streams, but the latter was more frequent in the streams. Metabolites were also detected, sometimes in higher concentrations than the original pharmaceutical but they were seldom analysed. The pharmaceuticals that caused more effects in the aquatic organisms were 17β-estradiol, estriol, estrone, acetaminophen, caffeine, carbamazepine, diltiazem, diphenhydramine, fluoxetine, norfluoxetine, sertraline, desmethylsertraline, methylphenidate and ciprofloxacin. The effects were varied, from bioaccumulation, endocrine disruption, impaired growth, reproduction inhibition, increased mortality and hatching disorder to morphological alterations, and decreased gross primary production and biomass. Streams had a higher mixture risk compared to the rivers. Important knowledge gaps detected are the low frequency of analysis of metabolites, the inefficient treatment of urban sewage regarding pharmaceuticals and the reduced number of studies on the impacts of pharmaceuticals at the aquatic community/population and functional level.