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Metals in the Environment

European Workshop

Metals in the Environment

Incorporation of Metal Bioavailability into Regulatory Frameworks

Der Workshop über die Einbeziehung der Bioverfügbarkeit in die Regulation von Metallen in der Umwelt fand am 1. und 2. April 2009 in Hamburg statt. Der Workshop wurde von der TuTech Innovation GmbH organisiert, an der Technischen Universität Hamburg (TUHH) veranstaltet und vom Umweltbundesamt unterstützt. 41 Experten aus Belgien, Frankreich, den Niederlanden, Schweden, Großbritannien, USA und Deutschland besuchten die Veranstaltung.

Der Zweck des Workshops war es die wissenschaftlichen Entwicklungen zur Bioverfügbarkeit von Metallen in der Umwelt und deren Berücksichtigung in der Regulierung von Metallen wie z. B. durch die REACH-Verordnung und die Wasserrahmenrichtlinie zu diskutieren.

Es wurden drei Hauptvorträge gehalten an deren Anschluss kurze Statements von Teilnehmern des Workshops gemacht werden konnten. Die Diskussion lief parallel in drei Arbeitsgruppen mit dem Fokus auf:
  • Diskussion der Modelle und Konzepte zur Bioverfügbarkeit
  • Biologie zur Metallaufnahme und
  • regulatorische Aspekte.

Alle Dokumente, (Flyer, Kurzfassungen der Hauptvorträge, kurze Statements einiger Teilnehmer, Zusammenfassung des Workshops) liegen in Englischer Sprache vor:

Kurzbeschreibung und Folien der Hauptvorträge des Workshops/abstracts and presentations of the workshop

Ms. Wiebke Drost (UBA) presented the concepts of the tiered approach taking metal bioavailability into account. It was stated that bioavailability is an important issue, because it would be an improvement for the hazard assessment to know how much of the toxicant is taken up from the different environmental phases. However, it is not clear cut which of the abiotic and biotic parameters determine the bioavailability. The guidance for metal risk assessment under REACH suggests a tiered approach which was briefly introduced. This concept considers the free ionic form of the metals to be the most bioavailable form. Depending on whether a risk has been identified or not, availability of physico-chemical data and availability of a speciation model or Biotic Ligand Model for the metal regarded an adequate tier-level has to be selected . The free metal ion concentration is considered the as the most relevant form for uptake. However apart from geochemical conditions which control free metal concentration, bioavailability is additionally a result of contaminant/particle interaction and can be superimposed by organisms' activity. Hence, the question arises whether this tiered approach indeed reduces the uncertainty or do new uncertainties emerge?
Taking metal bioavailability into account - The concepts of the tiered approach

Mr. Wolfgang Ahlf (TUHH) presented the need of knowing, in relation to metal bioavailability, the main uptake routes of different organisms in aquatic systems. Generally, it is considered that for most trace metals the free metal ions have the highest bioavailability . Thus, the presence of the hydrophilic complexing agent EDTA in water reduces the equilibrium concentration of metal ions with a corresponding decrease in the metal uptake. In the presentation data from experiments were shown which confirm this assumption. However, aquatic systems are dynamic and there is continuous interaction between solid phases (sediment, suspended matter) and liquid phases (freshwater, pore water). Transfers of metals between solid phases are regular processes, due to non-equilibrium situations.
 
The biotic ligand model (BLM) approach has been proposed for use in European Union (EU) risk assessments. The BLM provides a means to predict ecotoxicological effect of metals in the environment, but at present assumes that the most significant uptake is from the dissolved phase. Asking for the relevant exposure pathways for inorganic metals to organisms, the compartments water and sediment have been evaluated and in addition the importance of contaminated food. There is evidence in literature, that uptake occurs via the dissolved phase, metal complexes, dietary and particle-bound metals. It is apparent that dietary accumulation of metals is at least as important as metal uptake from the aqueous phase and in many cases dominates metal accumulation.
Metal Bioavailability - critical aspects

Mr. Joachim Heidemeier (UBA) summarized the requirements and consequences of considering bioavailability in the regulatory content. The Water Framework Directive (2000/60/EU) sets out a comprehensive framework for European water management. Aiming at reaching good ecological and chemical status for the European water bodies a water management is organized in river basin districts using a transparent approach with a clear-cut timeframe. Regulations regarding pollution from chemical substances refer to: priority substances and priority hazardous substances (PS and PHS), set out in Annex X, which are of community wide relevance and substances of regional concern, set out in Annex VIII.

For the PS and PHS Environmental Quality Standards (EQS) have been stipulated in Directive 2008/105/EU, for the substances of regional concern EQS shall be developed by the member states using a harmonized approach, also stipulated in the WFD.

One important step in the management cycle is the status determination of so called “water bodies”, the smallest units covered in the WFD. To that extent, the member states use three comprehensive monitoring networks with different tasks, consisting e.g. of approximately 7000 surface water monitoring stations in Germany.

If the assessment of the water body does not show the status “good”, the competent authorities must investigate the causes of the failure and implement measures in order to reach the status “good”. As these measures address the polluter for financing, the status determination must be based on clear and litigable decisions.

When drafting regulations for this decision process, scientific sophistication is one among several conflicting objectives e.g. required monitoring efforts and costs, transparency of the decision process or required time for results, which need to be balanced.
Consideration of bioavailability in regulation, requirements and consequences

Kurzstatements der Teilnehmer/short-statements of participants

Bruce Brown (UK Environment Agency)
BLMs in the Regulation

Erik Smolders (Division Soil and Water Management)
Soil

Katrien Delbeke (European Copper Institute)
Environmental Quality Standards derivation in the context of the Water Framework Directive
Accounting for Bioavailability of Metals: an Overview-Water

Ronny Blust (Department of Biology, University of Antwerp)
The Dynamics of Metal Accumulation and Toxicity Relationships (BIMBAM)

Christian Schlekat (Nickel producers Environmental Research Association)
Experience of Metals Risk Assessments in the Existing Substances Regulation Process: Technical Committee for New and Existing Substances discussions

Ed Tipping (Centre for Ecology and Hydology, Lancaster Environment Center)
Metal toxicity to macroinvertebrates in mine-affected streams, related to chemical speciation

Weitere Dokumente/further documents
Gutachten/report
Guidance R 7.13-2 der ECHA
Incorporation of metal bioavailability into regulatory frameworks—metal exposure in water and sediment