The EU is pushing for substantial improvements in freshwater quality by 2015; the Water Framework Directive (WFD) aims to improve waters that have been polluted by chemicals, and various measures (including the designation of Nitrate Vulnerable Zones) have been taken by member states to ensure water quality improves by the middle of the current decade.

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However, experts from the Helmholtz Centre for Environmental Research (UFZ) in Germany warned today that this target is unlikely to be met, and that agricultural activity is primarily responsible.

Presenting the findings of research conducted with colleagues from Landau, France and Switzerland, the UFZ researchers said high levels of toxic pollutants in European water are unlikely to be removed in time to meet the EU's 2015 deadline.

They warned that current measures for the improvement of water quality do not account for the effects of certain toxic chemicals and said their study demonstrates that the ecological risks posed by toxic chemicals are considerably greater than has generally been assumed.

Although discharges from urban areas, industrial products and municipal sewage treatment plants also played a major role, pesticides were found to be by far the most significant pollutants of freshwater systems.

Up until now, environmental authorities and the scientific community have considered toxic chemicals to be more of a local problem affecting only a few bodies of water, and have only drawn up lists of a relatively small number of key pollutants. The UFZ study, however, looked at ecological risks from chemical toxicants on a much larger scale (taking in several thousand European aquatic systems and more damaging substances).

EU requirements and targets on water quality currently focus on a series of so-called priority substances (around 40 chemicals classified as being particularly hazardous to the aquatic environment). "Fortunately the use of many of these priority substances is no longer permitted and therefore, their concentration levels are steadily decreasing in many parts... The real problem, however, is that a large number of chemicals which are currently in use are not taken into account at all in the context of water quality monitoring," said Dr. Werner Brack from UFZ.

Dr Brack and colleagues looked at the effects of pollution on three tiers of organisms: fish, invertebrates and algae (and similar microorganisms) across a number of European river basins.

The researchers from Leipzig and Landau warned that chemical toxicity is an ecological threat to almost half of all European bodies of water, and in approximately 15 percent of cases, vital microorganisms in freshwater systems are dying at an unsustainable rate as a result.

Threats posed by chemical pollution

The team said that making direct comparisons between different countries is difficult, but they did note that water quality appeared to be worst in France. However, they said this could be because French authorities have installed a "dense monitoring network and analysed water samples for a multitude of substances," whereas "In other countries… risks may remain unrecognized due to inadequate sensitivity in chemical analysis or an incomplete list of [polluting] compounds."

"Generally speaking we probably underestimated rather than overestimated the risks in our analyses", said Dr. Ralf B. Schäfer from the Institute for Environmental Sciences Landau. "The actual state and condition of European freshwater ecosystems is probably even worse."

Dr Schafer and colleagues called for pan-European measures to tackle pollution, including screening to capture potentially hazardous material, as well as known pollutants. "In this way", said UFZ's Dr Brack, "hazardous substances can be detected even before they have been placed on the priority list."

Brack and Schafer warned that there is an urgent need for action, especially with respect to current chemical monitoring activities.

Dr Schafer continued, "In practical terms, this means that urgent action is required at all levels, to ensure the sustainable protection of our aquatic ecosystems. The necessary steps to be taken range from general prevention of excessive chemical inputs into water bodies and the banishment and substitution of particularly problematic substances, up to a reduction in the application of agricultural chemicals and an improvement of sewage and wastewater treatment methods and technology."

"Unless there is noticeable change to the current situation, the objectives and targets of the Water Framework Directive will not be met, due to toxicity from chemicals in the freshwater ecosystems. In the long term this may also lead to risks for humans, caused by possible failure of ecosystem services, such as impairment of the self-purification capacity of water bodies."