The rivers in the region of Madrid contain at least 88 contaminants, according to a study performed by scientists from IMDEA and the University of Almeria (UAL), which has been published in the latest issue of Journal of Environmental Analytical Chemistry.

"Wastewater treatment plants fail to fully degrade many household products, such as biocides and aromas present in creams, toothpaste, shampoo, etc. As a result, they end up in the environment," says Amadeo R. Fernández-Alba, co-author of the study and Professor of Chemistry at the UAL.

The researcher underlines the fact that "there is no imminent danger, as the concentration and toxicity of most of the compounds is low, but the situation must be evaluated and monitored using parameters that guarantee they are harmless both in the short and long term." These substances are degraded quickly by the environment, but constant discharges make them appear persistent.

Fernández-Alba acknowledges that nobody knows the consequences that the combined presence of all these chemical compounds, many of which are medicines, could have on our health and the environment. Most of the 88 contaminants "are not regulated, although the possibility that they may achieve this status is not discarded."

The study focuses on the region of Madrid, but results would "certainly" be similar in the rivers in other densely populated regions, as was demonstrated in 21 large metropolitan areas in the United States and other super populated regions.

Samples were taken in three different months in 2008 from the rivers Tajo, Tajuña, Jarama, Alberche, Henares, Guadarrama, Aulencia, Manzanares, Lozoya and Perales. The largest concentrations of pollutants were found in the most populated areas in the centre and south of the region.

Risk of Emerging Pollutants

In order to confirm the nature of the 88 chemical compounds, the researchers used advanced analysis techniques (solid phase-extraction and liquid chromatography-mass spectrometry with state-of-the-art analysers). Concentrations ranged from 1 to 652 nanograms/litre for 9 priority substances or candidate pollutants, and from 110 to 9,942 ng/l for 79 emerging pollutants.

According to the European Union Water Framework Directive, there are "priority" pollutants, which are persistent and toxic (such as organochloride compounds), other "candidates" that are being studied to ascertain whether they could be priority substances and a third group of "emergents," such as pharmaceuticals and personal care products, with a low level of persistence and toxicity, but which could become problematic if they accumulate.

The study also indicates that three substances constitute a potential risk for aquatic organisms: ciprofloxacin (an antibiotic), ibuprofen and 4-AAA (metamizole or metamizole sodium metabolites). As a result, more in-depth research is recommended.

The researchers also confirm that two of the compounds analysed, caffeine and nicotine (on present in tobacco), could be used as quick indicators of the overall contamination of river waters due to human activity, without having to analyse all the substances.

"Building complete databases of pollutants and rivers will make it possible to compare, solve specific environmental problems and enhance the efficiency of wastewater treatment plants," Fernández-Alba concludes.

Note: If no author is given, the source is cited instead.

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