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Scientists from Germany, working with colleagues in France, Slovakia, Belgium and Spain, have released research which shows pesticides in watercourses are a more serious problem than had previously been assumed. The scientists analysed data on 500 organic substances in the basins of four major European rivers and concluded that levels of agricultural chemicals present could have harmful effects on organisms in the water.

The study revealed 38 per cent of the chemicals monitored were present in concentrations which could potentially have an effect on organisms. The teams, who published their findings in the journal Science of the Total Environment, concluded that contamination by organic chemicals is much more serious a problem than had previously been realised thoughout Europe.

Most of the substances classified as a risk to the environment which were measured in the study were pesticides; the majority of these are not on the European list of priority substances which have to be monitored regularly. The German researchers, from Helmholtz Centre for Environmental Research (UFZ), have therefore called for the list of chemicals which require monitoring under the EU Water Framework Directive to be revised immediately.

The EU Water Framework Directive aims to improve the environmental status of surface and ground water by 2015. Currently, the level of pollution in water is assessed based on a list of 33 ‘priority pollutants’; as over 14 million chemicals are on the market and over 100,000 of these are produced on an industrial scale, the authorities have to confine their monitoring to a manageable number of pollutants. European scientists are therefore working on methods to establish which pollutants should be treated with priority.

Chemical pollutants in European rivers

The international teams studied organic pollutants in the basins of the rivers Elbe, Danube, Schelde and the Llobregat. The European Commission has welcomed the researchers’ work, which it said is the first of its kind – studies which have developed a system which classifies organic pollutants on the basis of assessment criteria and the need for action.

The scientists classified a total of 73 compounds as potential priority pollutants, of which around two thirds were pesticides and herbicides. The most problematic of the pesticides was diazinon, which is already no longer allowed in Germany and Austria, though azoxystrobin and terbuthylazine, which are still allowed in Central Europe, also posed significant risks.

UFZ researcher Dr C. Peter von der Ohe commented, "Neither of these pesticides is on the list of 33 priority pollutants, which have to be monitored by authorities throughout the EU; Terbuthylazine is a compound that is structurally closely related to the priority pollutants simazine and atrazine, which may not be applied any more. This is a nice example how small structural modifications of chemical products may apparently improve the chemical status without mitigating any hazards to the aquatic ecosystems."

Success of clean water regulation

Despite their calls for more stringent legislation, the UFZ team applauded the work done so far to counteract the damaging effects of chemicals in water under the Water Framework Directive. The team’s research showed one third of the pollutants classified as priority a few years ago by the EU now no longer present a risk to aquatic life in the rivers studied.

This year has also seen good news for Britain’s waterways; in August, otters were reported to have recolonised every English county, having made a return from the brink of extinction after agricultural chemicals killed off the fish on which they depended between the 1950s and 1970s. Furthermore, Environment Agency figures showed UK waterways were at their cleanest in 20 years, with those at one time considered the most polluted having made much progress.

Nevertheless, conservationists maintain there remains a long way to go to ensure waterways are completely healthy and practices including the widely criticised ‘fracking’ for natural gas, which opponents claim threatens groundwater with massive pollution, still continue in the UK.