Opinion on the revised proposal for a List of Priority Substances in the Context of the Water Framework Directive (COMMPS Procedure) prepared by the Fraunhofer-Institut (Germany) - Final report Opinion adopted at the 11th CSTEE plenary meeting on the 28th of September 1999.
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The European Commission has requested the opinion of the CSTEE on the proposal for a list of Priority Substances in the context of the Water Framework Directive. This request includes a general opinion on the prioritisation method developed by the Fraunhofer-Institut Umweltchemie und Ökotoxikologie and several specific questions. In a previous opinion, the CSTEE had already expressed several recommendations. The present request focuses on the new procedures and proposals.

TERMS OF REFERENCE

The CSTEE is asked for its opinion about the choice of priority substances from the candidates generated by the Fraunhofer Institute. In particular, it is requested that the CSTEE comment on the appropriateness of the choice of the 5 metals proposed for inclusion in the first list by the Fraunhofer InstitutE. In addition, the CSTEE is specifically asked if there is sufficient evidence justifying to add mercury in the first priority list.

Within the documents provided to the CSTEE, a draft version of the Water Framework Directive, Document CSTEE/99/4A-Add.2, has been included. A crucial point in the definition of "pollution" has been detected. As expressed in the previous opinion, the quality status defined in the Directive focus on the scientific differences between « pollution » and « contamination ». A proper definition of pollution is therefore essential, and the CSTEE considers that, although not included in the terms of reference, the opinion must also address this issue.

COMMENT ON THE DEFINITION OF POLLUTION IN THE DRAFT WATER FRAMEWORK DIRECTIVE [VERSION PRESENTED AS CSTEE/99/4A-Add 2]

The CSTEE is concerned about the definition of "Pollution" in ARTICLE 2; PARAGRAPH 28. This definition is now ambiguous and can be interpreted as being based on presence (contamination) rather than effects.

Thus:

"Pollution" means the direct or indirect introduction......of substances [etc] ....... which may be harmful .......

can be interpreted to mean: substances with the potential to be harmful

The final qualifier phrase:

"...which result in damage to material properties, or which impair or interfere whith amenities and other legitimate uses"

does not include impairment to ecological qualities.

The CSTEE considers that the definition deviates from the approach of managing contamination in terms of likelihood not to impair ecological quality, resulting in a conceptual definition that is normally used for contamination rather than for pollution. The risk based approach is scientifically more defensible. In any event, deviations from the effects-based definition are not in the spirit of the Water Framework Directive, that focuses on predicting ecological quality, and undermines the use of quality standards, as specified under Article 13 Para 3 (gg).

Therefore the CSTEE strongly recommends to amend this definition in order to clearly express that pollution represents the level of contamination that impairs ecological qualities.

GENERAL OPINION ON THE PRIORITISATION METHOD

The CSTEE recognises the need for setting a transparent protocol aiming to determine which substances must be included in the Priority List, but it also considers the difficulties involved in the development of such a prioritisation method. The method proposed by the Fraunhofer-Institut Umweltchemie und Ökotoxikologie is scientifically sound and follows the basic principles of the current state of the art of environmental chemistry and toxicology. The CSTEE also acknowledges that the revised proposal has considered most of its previous recommendations.

As a complement to the previous statement on the quality of the study, the CSTEE considers appropriate to comment on three main issues related to the COMMPS procedure:

a) The proposal combines two different approaches for exposure scoring, namely monitoring data and modelling estimations.

Monitoring data provide an excellent basis, from direct observation, to get information on European environmental conditions. However, monitoring data cannot be used as the single scoring method because the available information is incomplete and only covers a set of substances which were considered "relevant" in the past. Thus, the current monitoring information is biased by previous decisions on which substances should be monitored. Those decisions taken in the past: (1) mostly focused on Member States needs, knowledge and capacity; (2) do not necessarily address the same aims and goals of the List of Priority Substances under the Water Framework Directive, and (3) cannot faithfully represent the current water pollution problems. Therefore, it is important to incorporate a second system, to allow inclusion in the final list, of substances with a high potential risk for aquatic organisms for which no monitoring information is available to date.

In addition, the current monitoring data do not provide enough information on the contamination conditions of each sampling point. These points may represent either problematic areas located downstream specific emissions (comparable to local Predicted Environmental Concentrations: PECs) or points located far away from the pollution sources, (comparable to regional/continental PECs). Therefore it is not surprising to find no correlation between monitoring data and model estimations. Both methods have disadvantages and benefits and must be run as parallel approaches before being combined in a final step, as proposed by the Fraunhofer-Institut Umweltchemie und Ökotoxikologie and recommended in a previous opinion of the CSTEE.

The use of other priority lists to select candidates for modelling was also recognised as a sound approach in the previous opinion of the CSTEE, but it also biases the selection and raises some concern on the non consideration of relevant substances (see below).

b) Organic substances and metals have basic differences regarding the estimation of their potential hazard and risk for the aquatic environment. Therefore, they must be treated as independent groups but following as far as possible similar approaches.

This condition was also included in the previous set of recommendations of the CSTEE and has been considered in the revised proposal. However, in the scoring system for metals, the Fraunhofer-Institut Umweltchemie und Ökotoxikologie proposal does not include the indirect effects related to their bioaccumulation potential. The CSTEE recognises that, as mentioned in the report, the large differences in the environmental concern of the bioaccumulation potential among the different metals could justify excluding this aspect from the scoring system. Nevertheless, the potential for bioaccumulation and biomagnification is indeed a key issue in the environmental hazard of certain metals and this aspect should be included in the final step using expert judgement.

c) The combination of the different lists requires an expert judgement approach.

sound.

In addition, as previously pointed out, this expert judgement should also consider the potential for bioaccumulation/biomagnification of certain metals. This aspect is not considered in the revised proposal.

ADDITIONAL REMARKS

The COMMPS procedure is scientifically sound and the presence of the compounds that are included in the final priority lists is well justified.

However, some weaknesses can be observed:

The process starts with a selection of candidate substances which is a mere compilation of several existing lists of prioritised compounds. This will hamper the possibility to include non-listed "new" substances. There is a large number of organic compounds in use today and a more objective method would be to take advantage of their properties to identify candidate compounds. This approach is today taken by several other organisations (UNEP, UN-ECE, OSPAR, HELCOM) and it is important that any high priorities from them can be taken into account when choosing candidates for the WFD.

The criteria used for EU-wide relevance, when using monitoring data for the selection of substances, further decrease the possibility of including "emerging" compounds in the prioritised list.

Existing chemicals may achieve high producing volumes increasing their potential to contaminate the aquatic environment and requiring monitoring e.g. MTBE (Methyl-tert-butyl-ether).

It is essential to identify which substances are missing from the lists. The List should be kept open to the introduction of additional substances of concern, particularly those that are not included in other priority lists, and that, therefore, have not been considered in the COMMPS procedure. A timely updating of the substances should be planned.

The cut-off value for molecular weight (700) when scoring for indirect aquatic effect seems to be low. Even compounds with molecular weights close to 1000 can be taken up by fish. This cut-off value must be considered as a screening procedure, chemicals with higher molecular weights should be incorporated if the available information demonstrates their toxicity for aquatic organisms.

When excluding substances from the initial lists, great care needs to be taken in making sure that they are not relevant with regard to their Community-wide significance. For example the sentence to justify the exclusion of iron " adverse environmental effects of iron emissions are not reported in the literature" is not correct. Iron hydroxides are emitted from old coal mines and are known to adversely affect aquatic communities.

The COMMPS procedure excludes the so-called "historical pollutants" for which legislative measures such as bans or severe restrictions already have been imposed. These chemicals must not be managed in the same way as currently used chemicals. Nevertheless, the possibility of recent pollution due to accidental emissions in the environment or disposal of old stocks is still existing. In addition, persistent pollutants regulated by the EU which share a global distribution may still for many years be of serious environmental concern at a European level.

Thus, although the presence of PCBs in river sediments can be regarded as an "historical pollution" problem, the introduction of additional amounts of PCBs in the aquatic environment related to leaching and run-off from remaining use, contaminated lands and hazardous wastes plants must be considered as a current contamination issue. Another relevant example is the recent event of DDT pollution in lake Maggiore in Italy.

Therefore, some old chemicals of particularly high concern should not be excluded from the COMMPS procedure.

From a regulatory point of view, the reason for including these chemicals in the list is the need for assessing the effectiveness of existing measures and the evolution of water quality as a consequence of the measures.

The ultimate purpose of the WFD is to characterise the quality of European waters. Thus, it is considered that some selected compounds, in particular PCBs and DDTs must be included in monitoring programmes at the EU level. Therefore, these substances should be added as priorities. Appropriate monitoring plans should be implemented specifically adapted to the characteristics of each "historic" pollutant, including when relevant monitoring programmes on biological samples (see below) in addition to water and sediment measurements.

Some specific comments can be made on plant protection products (PPPs) for two different reasons:

- The relevance of different PPPs is not the same all over Europe due to substantial differences in crops and agricultural practices;

- The market of PPPs is rapidly changing and evolving: every year new chemicals are registered and old chemicals are no longer utilised.

The monitoring-based priority list includes a number of plant protection products considered as high concern chemicals at the European level. The modelling approach has been considered inadequate (too simple) for PPPs, therefore PPPs have not been included in the modelling-based list. This proposal can be assumed as a first-step priority lists for PPPs. In perspective, priority lists for the monitoring of PPPs should be periodically updated in function of changes of the market.

In addition, river basin priority lists should be set up in function of agricultural practices. Both, updating and local lists should be based on risk assessment information made available through Directive 91/414/EEC.

In order to better assess the risk from secondary poisoning related to chemicals with a potential for bioaccumulation and/or biomagnification through the aquatic food change, inclusion of monitoring data from biological samples should be considered. It is also recommended that for those substances which are of concern in terms of secondary poisoning, measured concentrations should be compared not only with the Environmental Quality Standard developed under the basis of effects on aquatic organisms, but also considering the toxicity for aquatic and terrestrial vertebrates exposed to the chemical through the consumption of contaminated aquatic organisms. For some substances, the concentrations recommended for the protection of the aquatic ecosystems can be higher than the threshold values required for the protection of the consumers of aquatic organisms and, hence, of the non-aquatic communities associated to the aquatic ecosystems. Therefore these aspects must be considered in a prioritisation scheme.

The aggregation of monitoring data is based on arithmetic means and yet, as the report acknowledges, distributions of MECs are unlikely to be normally distributed. Under these circumstances, geometric means are usually more appropriate. The report needs to explain why this approach was not followed.

Nevertheless, the CSTEE considers that the data base containing monitoring data from the MS is a very valuable tool for many studies and it should be made available not only to the scientific community, but also to any interested party.

In order to improve the comparability of monitoring data, there is a need for the harmonisation of monitoring plans and for the development of standard protocols for the reporting of monitoring data at European level. These protocols should include description of criteria for selecting sampling strategies.

SPECIFIC QUESTIONS.

METALS

As previously pointed out, the procedure followed by the Fraunhofer-Institut Umweltchemie und Ökotoxikologie, that considers metals in a separate list but following a similar approach is deemed to be the best option.

However, the details related to the environmental chemistry and toxicology of metals have not been sufficiently considered. Some basic points are mentioned below:

- Monitoring data on metals cannot be treated in the same way as on synthetic organic chemicals. For most organic chemicals, monitoring data estimate the environmental concentration related to the emission of that particular chemical. For metals, monitoring data represents the influence on background concentrations of a large list of human activities that takes metals from some specific places and spread significant amounts into the environment, thus modifying the natural cycles of these elements. Only a limited proportion of these emissions corresponds to the "regulatory understanding" of the life-cycle of metallic organic and inorganic chemical substances. Hence, the levels of, for example, cadmium in water have a meaning different from that of atrazine.

- The amount of ecotoxicological information on metals is much higher than for most organic pollutants (i.e., only in the AQUIRE database more than 2,000 references on the toxicity and bioaccumulation potential of mercury can be found). The same holds true for the understanding on their environmental hazard. Long term concerns mostly dealing with bioavailability, such as bioaccumulation and biomagnification through the food chain, chemical speciation in the environment, indirect hazards for human consumers of contaminated food, etc., must be considered on a case-by-case basis.

- In particular, the potential for bioaccumulation/biomagnification, and the long-term consequences of anthropogenic emissions must be specifically addressed. The environmental hazards of an essential metal, such as zinc, are clearly different from those expected for mercury.

- The toxicity of metals to aquatic organisms depends on water quality conditions and the resulting differences can cover several orders of magnitude. The comparison of monitoring data with effect estimations should consider not only background concentrations but also water quality conditions such as hardness and pH.

- Monitoring of metals provides highly relevant information and a large number of data (i.e., about 10000 measurements above the detection limit) widely distributed (i.e., 13 Members States for cadmium, 10 for mercury). Under these circumstances, the uncertainties on the European relevance of the CONCENTRATION/PNEC ratio are much lower than for a chemical with point source emissions, with less data and less widely distributed information.

Considering these issues, the direct application of the TGD-PNEC factors and R-phrases scoring system is not appropriate for metals (in fact both the TGD and the Classification and Labelling procedure recognise the peculiarities of metals and metallic compounds in terms of hazard and risk assessment). Therefore, the PNEC values estimated for metals should be refined to properly address their ecotoxicological characteristics. It must be also considered that the CSTEE has already accepted in previous opinions PNEC values for arsenic about 20 times higher than those used in the report as well as the convenience of using probabilistic approaches in the PNEC derivation for cadmium.

An alternative approach, using the same effect parameters (direct, indirect and human effects) and scores (5,3,2) but focusing on the scientific knowledge available on the environmental behaviour and the ecotoxicological hazards of each metal will be helpful.

In addition, the selection of "five" metals for the final list is arbitrary. Considering that metals represent a reduced number of elements, and that after their emission into the environment there is no degradation but just re-distribution in the biosphere, a proper risk assessment should be done for all those metals with enough monitoring data. On this basis, all metals showing a significant risk for aquatic organisms related to either water or sediment exposures should be included in the Priority List.

MERCURY

Mercury is considered one of the most dangerous metals in the aquatic environment. This is due to its high toxicity and its potential for bioaccumulation/biomagnification, particularly under conditions favouring the transformation of inorganic mercury into organic mercury forms, a phenomena that increases the bioavailability of mercury for aquatic organisms and their predators.

Although mercury methylation is particularly relevant in saltwater sediments (King et al., 1999 ¹ ), it must be considered a general environmental problem including freshwater systems (i.e., Miskimmin et al., 1992 ² ). Therefore, for a proper management of the risk of mercury for aquatic ecosystems, its monitoring in freshwater, estuarine and marine systems is considered essential. Freshwater systems most at risk of mercury bioaccumulation in fish, are those with low acid-neutralising capacity and low pH (Spry and Wiener, 1991 ³ ). However, significant aquatic food change biomagnification has recently been reported for other systems with substrates of naturally high mercury deposits with increased bioavailability due to multiple ecological factors (Evers, et al., 1998 ⁴ ). Both sets of conditions can be found in several locations within the EU, and justify the inclusion of mercury in the priority list for both fresh and saltwater systems.Mercury is highly toxic for aquatic organisms, but the main ecological hazard comes from its bioaccumulation/biomagnification through the aquatic food chains, and this is still poorly understood in quantitative terms (i.e., Meyer, 1998 ⁵ ). Significant levels of mercury have been found in fish, even in areas which are not supposed to be affected by specific emissions (i.e., Rose et al., 1999 ⁶ ). In fish, mercury is mostly present as the methylated form, thus constituting a significant hazard for fish-eating vertebrates. The toxicity of mercury, particularly methylmercury, for wildlife including birds and mammals has been recently reviewed by Wolfe et al. (1998 ⁷ ). Damage to nervous, excretory and reproductive systems are common findings associated to mercury poisoning.

The low relative score found in the report can be related to a straight-line application of the ranking procedure which does not consider several environmental concerns of mercury, related to indirect and human health effects as well as long-term concerns.

Taking into consideration the available information, the CSTEE considers that there is enough evidence to include mercury in the List of Priority Substances in the context of the Water Framework Directive.

List of documents made available to the Scientific Committee on Toxicity, Ecotoxicity and the Environment via its Secretariat to help it reach the opinion requested by the services of the Commission on the subject of "Water Framework Directive"Follow-up - Part B - Revised Proposal for a List of Priority Substances in the Context of the Water Framework Directive (COMMPS Procedure) prepared by the Fraunhofer-Institut (Germany) - Final report

CSTEE/99/4(b)

Terms of reference for the consultation of the CSTEE on a Revised proposal for a list of priority substances in the context of the Water Framework Directive (COMMPS procedure)

CSTEE/99/4B

Draft final report "Revised Proposal for a List of Priority Substances in the Context of the Water Framework Directive (COMMPS Procedure) prepared by Fraunhofer-Institut (Germany) - March 1999.

CSTEE/99/4B - Add. 1

Working Document M0498WD1

"Priority Setting of substances dangerous for the aquatic environment"

15. March 1999.

CSTEE/99/4B - Add. 2

Draft Final Report by Dr. Steffen Uhlig (Germany)

"Assessment of options of the statistical treatment and evaluation of monitoring data within the COMMPS procedure"

24. March 1999

CSTEE/99/4B - Add. 3

Final report "Revised Proposal for a List of Priority Substances in the Context of the Water Framework Directive (COMMPS Procedure) prepared by Fraunhofer-Institut (Germany) - June 1999.

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¹ King JK, et al. 1999. Environ. Toxicol. Chem. 18: 1362-1369

² Miskimmin BM et al., 1992. Can. J. Fish Aquatic Sci. 49:17-22

³ Spry DJ and Wiener JG. 1991. Environ. Pollut. 71:243-304.

⁴ Evers DC et al., 1998. Environ. Toxicol. Chem. 17:173-183.

⁵ Meyer MW. 1998. Environ. Toxicol. Chem. 17:137-138

⁶ Rose J., et al. 1999. Environ. Toxicol. Chem. 18: 1370-1379

⁷ Wolf MF, et al., 1998. Environ. Toxicol. Chem. 17:146-160.