Study reveals that urban streams are polluted by pharmaceuticals
A study by the University of Coimbra has concluded that urban streams are polluted by a wide variety of drugs. This study was carried out as part of the doctoral thesis of MARE researcher Fernanda Rodrigues, supervised by Maria João Feio.
The aim of the research was to understand the state of contamination of urban streams by pharmaceuticals and their impact on the ecosystem and aquatic organisms. To this end, 49 urban streams were studied, 3 of them in Portugal, where 139 drugs from 10 different therapeutic groups were detected.
‘Urban streams, in addition to rivers, are a critical freshwater ecosystem when it comes to the occurrence of drugs. They run through highly urbanised areas and given their small volume of water and low dilution capacity, they can become highly polluted and then carry these pollutants into the main rivers,’ explains Fernanda Rodrigues. ‘The urban streams studied are contaminated by drugs from various therapeutic groups and there are various impacts on aquatic organisms, from bioaccumulation to, for example, morphological changes,’ she concludes.
The team of researchers detected drugs such as diclofenac, ibuprofen and paracetamol (analgesics, anti-inflammatories, anti-pyretics and anaesthetics); clarithromycin and erythromycin (antibiotics, anti-fungals and anti-pruritic drugs); fluoxetine and citalopram (psychotropic drugs); estrone, 17ß-estradiol and ethinylestradiol (hormones); and genfibrozil (lipid regulators). In Portugal, 8 of these drugs were found in the three streams studied (the Mondego, Tagus and Guadiana rivers), including the antidepressant fluoxetine, which represents a high risk for aquatic biodiversity.
‘Our results also show that it is important to develop effective public policies to protect and safeguard urban aquatic ecosystems and, ultimately, human health,’ says the MARE researcher. According to the study, ‘the effects on aquatic organisms and ecological processes were varied, ranging from bioaccumulation, endocrine disruption, impaired growth, inhibition of reproduction, increased mortality and hatching disorders to morphological changes and decreased gross primary production and biomass’.
The article in which this study was published also contains recommendations such as: ‘new studies on the occurrence and impact of pharmaceuticals in riverine ecosystems, especially in countries where this issue has never been studied; the use of the Watch-List as a guide for other countries to start monitoring some of these contaminants; diverse investigations involving metabolites and transformation products of pharmaceuticals, other sources of pollution not normally considered (such as sewage drainage systems), the influence of dry/wet seasons for some pharmaceuticals, as well as effects on the structure and functioning of aquatic communities’.
Maria João Feio also said that the study is being extended to more European cities and that samples have already been taken from various urban streams in order to ‘de-characterise the drugs and analyse the impacts on microalgae and aquatic invertebrate communities’. The MARE researcher believes that the number of streams analysed is small, and that there is a need to continue studies to detect drugs in more urban streams.
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