EU river survey highlights most common pollutants

Scientists have measured the concentration of 35 water-soluble organic pollutants in samples from over 100 European rivers. They propose "indicative warning levels" for each chemical, above which further investigation should take place.

A survey has looked at soluble persistent organic pollutants in rivers across the EU for the first time.1 These compounds pose a particular risk because they can pollute groundwater and drinking water sources.

The EU’s water framework Directive calls for ‘good ecological status’ by 2015 and sets maximum concentrations known as environmental quality standards (EQSs) for 33 priority substances. These are pollutants "presenting a significant risk to or via the aquatic environment" (ENDS Report 379, p 48).

Last year, the European Parliament proposed another 28 substances to be added to the list (ENDS Report 389, p 50), including pharmaceuticals, biocides, bisphenol A and the non-stick chemical perfluorooctanoic acid (PFOA).

To establish priorities for setting EQSs for other pollutants, the European Commission’s Joint Research Centre tested for 35 different water-soluble organic pollutants in samples collected from more than 100 rivers located in 27 European countries. Nine major UK rivers were tested, including the Tyne, Tees, Severn and Clyde.

Some of the most frequently detected substances included: 4-nitrophenol, an intermediate used to make drugs, pesticides and dyes; nonylphenoxyacetic acid, a breakdown product in nonylphenol ethoxylate detergents; the non-stick chemicals PFOA and perfluorooctane sulphonate (PFOS); and anti-epileptic drug carbamazepine (see table).

PFOA occurred in 97% of samples at 12 nanograms per litre on average. West Virginia residents whose water was contaminated by PFOA qualified for a class-action lawsuit against manufacturer DuPont if their water had more than 50ng/l of the chemical (see p 29). A number of EU samples exceeded this level.

Chemicals detected at particularly high average concentrations included painkiller ibuprofen, oestrogenic industrial intermediate nonylphenol, antibiotic sulfamethoxazole and the herbicide diuron. Use of nonylphenol has been restricted since 2004 and diuron was banned in 2007 (ENDS Report 354, p 47 ). Both are already on the list of priority substances.

In general, pesticides were found at low levels, perhaps because sampling took place in the autumn when applications are rare. Year-round concentrations may have been underestimated.

Of all the rivers studied, only 11 were classified as very clean. These were in Austria, Denmark, Estonia, Lithuania, Malta, Norway, Slovenia and Sweden and contained only a few substances at low concentrations. The most pristine samples came from sparsely populated regions in Estonia, Lithuania and Sweden.

The authors proposed "indicative warning levels" for each of the chemicals measured. For most compounds the indicative warning level was set close to the 90th percentile, which encompasses the 90% of samples with the lowest concentration. Any sample above this benchmark could then be considered "not normal" and warrant further investigation, they suggest.

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