Executive Summary

EU and international policy have been tackling water and environmental pollution for nearly 50 years. Gross chemical pollution, exemplified by “dead rivers”, has been successfully addressed in many cases. However, in its recent report, “European waters — Assessment of status and pressures 2018”, based on data from Member States on the implementation of the Water Framework Directive (WFD), the European Environment Agency (EEA) found that despite action to reduce chemical pollution over many years, only 38 % of EU surface water bodies are in good chemical status. 46 % are not achieving this status, and 16 % are in unknown chemical status (EEA, 2018a).

The risk presented by hazardous substances is assessed under the WFD by comparing concentrations in the environment with environmental quality standards (EQS) for single substances. Some of the substances show high toxicity directly to organisms in the water, while others accumulate up the food chain and may therefore harm predators, which includes humans eating fish. This single substance approach has been used for many years, and fits well with regulation which seeks to control chemicals at source.

However, our understanding of the complex interactions between chemicals and living organisms has greatly increased over the last 20 years. At concentrations lower than those which kill directly, harmful chemicals may exert more subtle effects on organisms, for example limiting their ability to reproduce. Concern has been raised in relation to “the cocktail effect”, referring to mixtures of substances which may be present at low concentrations and which may combine in complicated ways to affect health.  Achieving good status in surface waters may therefore require a better understanding of the subtler links between ecological and chemical status. Some approaches to improving this understanding are described in chapter 2.

Improving protection against chemical risks means we need to know what the risks are. Returning to what monitoring and reporting currently provide, chapter 3 gives more specific information on the chemicals recently reported as causing failure under the WFD. It describes fate, status and pollution, and provides examples of measures for the 15 substances most commonly causing failure across Europe under the WFD, and a further 15 identified at Member State level as River Basin Specific Pollutants.

Among these substances, those described as “ubiquitous” cause the most failures. They are persistent and toxic substances, distributed worldwide, in many cases over many years. Mercury is the major cause of failure: nowadays in Europe its main sources from human activities are from coal burning for power generation and the chemical industry, while substantial amounts are also released from urban waste water treatment plants (EEA, 2018b). Brominated diphenylethers (pBDEs), which were used as flame-retardants, and polycyclic aromatic hydrocarbons (PAHs) which arise both naturally and from human sources during the burning of organic matter, are also leading causes of poor surface water quality. If these ubiquitous substances are omitted, only 3% of surface water bodies in Europe fail to achieve good chemical status.

Several other substances used in products enter surface water, mostly via urban waste water treatment plants. Examples are nonylphenols, used as surfactants, and the plasticiser DEHP. Historically, pollution by metals was caused by industry and mining, but significant sources now include our homes, buildings and untreated storm water discharges. Agriculture is the major user of pesticides, though we have limited data to show that as a source, while municipal and domestic uses can be significant in urban waste water. The herbicides isoproturon, metolachlor, MCPA and terbuthylazine are discussed, as is the insecticide lindane, already heavily regulated but a very persistent and volatile substance. Some biocides, like tributyltin were used to protect vessels from “fouling” by mussels and other water organisms.


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Chapter 4 considers some strategies and practical approaches as examples of the development of water and chemicals policies. The final chapter then draws some conclusions:

Most failures in chemical status of surface waters can be attributed to 3 groups of substances: mercury, PAHs and pBDEs. Specific actions targeting these priority substances are:

Further effort to reduce emissions of mercury from urban waste water treatment plants, either upstream or before discharge, seems necessary.
Improved understanding of pressures from emissions reporting needed to be able to implement effective measures to reduce pollution of water by PAHs.
Improved understanding of the environmental pathways of pBDEs, to identify whether measures can be implemented which would limit further dispersal.

Emissions data on pollutants as reported in Europe (for WFD, E-PRTR or WISE-SoE) could give an important overview on emissions, impact of measures and trends. However, they are incomplete and inconsistent and too often exclude diffuse sources. Improvements to our understanding of emissions could be achieved by:

Streamlining emissions reporting, so that robust data collected for one obligation would satisfy European emissions reporting requirements;
Improvement in the monitoring and reporting of diffuse sources, to ensure that pressures are correctly understood and measures can be appropriately targeted.

For some priority substances, low numbers of water bodies failing to achieve good chemical status suggest that, assuming monitoring and reporting are accurate, measures have been effective in preventing the entry of these chemicals into surface waters. This is a success for European water and chemicals policies.

If these substances were no longer priority substances, resources spent on them could instead be used monitoring substances currently considered to present a risk.

The success of measures against gross chemical pollution means that we increasingly look to ensure the good ecological status of water bodies. Scientific advances have identified sub-lethal effects caused by chemicals which can harm the healthy functioning of an organism. Applying such techniques in the assessment of ecological status would be one way to  improve protection from harmful chemicals under the WFD.

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