Derivation of Aquatic Quality Standards for Priority List Substances not Covered by Existing UK Regulations
A key element within the Water Framework Directive concerns the derivation of Environmental Quality Standards (EQSs) as a means of setting benchmarks for the quality of surface waters, sediments or biota. Article 2 of the Directive defines an EQS as the concentration of a particular pollutant or group of pollutants in water, sediment or biota that should not be exceeded in order to protect human health and the environment. Annex 5 then goes on to describe the procedure for deriving these standards. This report is concerned with the procedure described in Annex 5 of the Water Framework Directive, and in particular how the outcomes from using that procedure (i.e. the resulting EQSs) compare with current UK practice.
The report summarises the findings of the project to derive quality standards for seven substances/ groups of substances using the UK method and that proposed by the Fraunhofer Institute for deriving Quality Standards under the Water Framework Directive and on the assessment of the cost implications of the standards proposed (Parts 1,2 and 3 of the work programme).
Specifically, the following chemicals were considered:
The UK method only derives standards for freshwater and marine waters, while the proposed EC methodology also includes thresholds for the protection of freshwater and marine sediments, secondary poisoning to higher life forms, dietary exposure in humans and abstraction to drinking water.
Based on the information available it has been possible to derive quality standards for the protection of fresh and marine water using the UK methodology for seven chemicals: anthracene, pentabromodiphenyl ether, C10-13 chloroalkanes, chlorpyrifos, dichloromethane, benzo-a-pyrene and fluoranthene. Using the proposed EC methodology, it has also been possible to derive ‘overall’ standards for the same substances and also benzo-k-fluoranthene. Insufficient data are available to derive quality standards using either the UK or proposed EC methodology for six chemicals; octabromodiphenyl ether, decabromodiphenyl ether, benzo-b-fluoranthene, benzo-g,h,i-perylene, benzo-k-fluoranthene (only for the UK methodology) and indeno-1,2,3-cd-pyrene.Where appropriate, comparisons are made between the standards derived applying the UK methodology with those proposed by the Fraunhofer Institute in September 2002 (Lepper 2002) who used the EC method to derive standards from data supplied by EC Member States and other stakeholders.
In carrying out a critique of the EC and UK methodologies, some important points have arisen. In principle, the EC method (that proposed by the Fraunhofer Institute) has much in common with the current UK approach, being based on a ‘critical data/safety factor’ paradigm. However, there are important differences in detail. In the EC method, reliance is placed on the effects assessment part of the EU Technical Guidance Document (EU TGD) and similar schemes used to evaluate plant protection products. This reflects an understandable desire to promote consistency between Member States and with existing regulatory schemes. However, a number of issues have come to light:
The proposal to derive sediment quality standards and to allow compliance assessment on the basis of contaminant levels associated with suspended particulate matter (SPM) gives rise to some particular concerns:
In our view, a more effective strategy would be to develop non-statutory sediment guidelines within a tiered risk assessment framework.
Finally, we draw attention to concerns raised by the Royal Commission on Environmental Pollution about the expression of standards as an absolute threshold (such as a Maximum Allowable Concentration, MAC) without proper consideration of the sampling protocol and measures to assess the level of confidence in determining compliance or non-compliance. The UK government have accepted these principles and so we recommend that further consideration of the compliance assessment measures is needed if a MAC is to be derived.
With respect to the cost assessment this can be summarised by substance as follows:
Benzo-b-fluoranthene, benzo-g,h,i-perylene, indeno(1,2,3-cd)pyrene
No standards are proposed and therefore no cost assessment has been undertaken.
No standards are proposed and therefore no cost assessment has been undertaken. However, available data on solubility and effects suggest no additional measures will be required and hence no cost implications are expected.
No standards are proposed. However, the uses of the substance that contribute to emissions to the water environment are to be banned under Directive 76/769/EEC. Therefore no additional measures are expected to be required and no cost implications are expected.
Standards have been proposed. However, the uses of the substance that contribute to emissions to the water environment are to be banned under Directive 76/769/EEC. Therefore no additional measures are expected to be required and no cost implications are expected.
Standards have been proposed. However, the uses of the substances that contribute most of the environmental emissions, are expected to be banned. Therefore, no additional measures are expected to be required and no cost implications are expected.
Standards have been proposed. Exceedances could be considerable but monitoring data are incomplete. Remediation measures are likely to focus on changes to farm practices, with costs expected to be moderate overall, although potentially significant for individual farmers. The cost estimates are insensitive to the methodology used for the derivation of the EQSs.
Standards have been proposed. Monitoring data are patchy, but point towards limited exceedances in well-defined locations, possibly linked in certain serious cases with historic pollution, and hence outside of the scope of Article 16. This suggests that costs of compliance measures are likely to be low overall, but could potentially be significant in some local cases. EQSs derived using the UK methodology are much less stringent than the ones derived using the EC methodology, although based on the data the implications for exceedance appear limited.
Polycyclic aromatic hydrocarbons
The assessment is limited by a lack of monitoring data, and refers only to a comparison with the situation observed over the period 1993-1995. Since then we would have expected possibly significant improvements in water quality status.
The cost implications for meeting the PAH EQSs could be considerable. If the strictest EQSs are adopted, these could amount to billions of pounds. Adoption of less stringent standards is likely to significantly reduce non-compliance, but remaining exceedances could still require considerable expenditure, possibly hundreds of millions of pounds, or more. Cost implications can only be described as high, therefore. However, this is subject to information on the impacts of recent and planned investments in wastewater treatment by industry and water companies, as well as expenditure to address combined sewer overflows, which has not been available in structured form.
Copies of this report may be available as an Acrobat pdf download under the 'Completed Research' heading of the Research Page on the DWI website.