Activity:Development of a Guidance Document on the Implementation of Bioavailability-Based

Activity:Development of a guidance document on the implementation of bioavailability-based EQS for metals,

For WG Chemicals as part of the Water Framework Directive CIS Work Programme (2016-2018) endorsed by the Water Directors

“Guidance on implementing metals EQS, including the application of Biotic Ligand Models and consideration of natural backgrounds”

TERMS of REFERENCE

1. Introduction

Substantial progress has been made in the past few decades in our understanding of how differences in water chemistry can affect the toxicity of metals toward aquatic biota. Central to this progress has been an improved appreciation on how metals interact with organisms at the surface of biological membranes (e.g. epithelium). Scientific evidencesuggeststhat the toxicity of metals is dependent on a range of water quality parameters such as hardness, pH, and dissolved organic carbon (DOC);these parameters influence the amount of metal that is actually bioavailable. It supports the long established consideration that measures of total metal in waters have limited relevance to potential environmental risk (e.g. Campbell 1995).

Biotic Ligand Models (BLMs) are mechanistic models that have been proposed as tools to evaluate quantitatively the manner in which water chemistry affects the speciation and biological availability of metals in the aquatic environment(Paquinet al. 2002;Niyogi and Wood 2004). In this construct, the free-metal ion concentration (or activity) is considered as a predictor of metal bioavailability, and metal complexation by inorganic and organic ligands in the exposure medium should lead to a decrease in metal bioavailability. Similarly, other cations (e.g. H+, Ca2+ and Mg2+) would be expected to compete with the metal ion for binding at the epithelial surface, affording a certain protection against metal toxicity.

The BLM approach has gained widespread acceptance among the scientific and regulatory communities[1] because of its potential for use in developing water quality standards and in performing aquatic risk assessments for metals. BLMs can be used to predict both acute and chronic toxicities of a metal in a water body, provided that the physicochemicalproperties of that water body are known. When sufficiently developed and validated, BLMs can be used to calculatesite-specific 5% hazardous concentrations (HC5) values for all sets of water chemistry conditions which may be encountered within a region[2](see Merrington et al.2016 for an example with Ni).

Each of the existing chronic BLMs (see Copper RAR 2008; Nickel RAR 2008; Zinc RAR2010)has been developed and validated for particular ranges of pH, Ca and DOC. The validation boundaries of the BLMs represent the extremes of water quality conditions over which they have been shown to work (i.e. the range of tolerance of the species commonly used in ecotoxicity testing over which BLMshave been developed). Recently efforts have been made to extend the boundaries of the zinc BLM to higher pH (e.g. Nyset al. 2016),and the increased applicable pH range can allow now the BLM to be applied to a larger proportion of European surface waters. Still, further BLM “calibration” to soft, and/or acidic waters is needed so that the BLM can be reliably applied in Nordic countries.

The Water Framework Directive explicitly acknowledges the issues of bioavailability and naturally occurring concentrations for metals. Daughter Directive to the WFD on EQSs (2008/105/EC) (EC, 2008) as amended by Directive 2013/39/EU states in Annex I, part B.3:

Member states may, when assessing the monitoring results against the EQS, take into account:

-Natural background concentrations for metals and their compounds if they prevent compliance with the corresponding EQS value; and

-Hardness, pH or other water quality parameters that affect the bioavailability of metals, the bioavailable concentrations being determined using appropriate bioavailability modelling.

Directive 2013/39/EU(EC 2013) has set “generic” environmental quality standards (expressed as annual average) for both nickel and lead that reflect conditions of high bioavailability that are likely to be observed in European freshwaters; these standards should be protective of at least 95% of the surface waters in the most sensitive region and,as such, could be applied across the whole Europe. The bioavailability-based EQS for Ni is based on a “full” chronic BLM, whereas the EQS for Pb is determined through an availability correction based on DOC concentration. Other metals, for which“full” chronic BLMs have been developed and validated, such as Cu and Zn, are identified as river basin specific pollutants (RBSP) and may not have consistent environmental quality standards across Europe.These efforts to incorporate the bioavailability concept into the derivation of EQS under the WFD have received support from the Scientific Committee on Health and Environmental Risks (SCHER 2010).

Under the WFD, metal bioavailability is considered both at the EQS derivation and implementation stages. To assess compliance, the “generic” EQS is compared to the bioavailable fraction of the dissolved metal in a sample, as determined by the (local) physico-chemical characteristics of the water, and can be estimated using a biotic ligand model or other availability-based approaches.

One of the major difficulties in implementing BLMs within the WFD compliance assessment is the amount of information which is needed for performing the BLM calculations (e.g., the chronic Cu BLM requires 10 input parameters), making the model difficult to operate at the scale of a EU-wide monitoring programme. Concerns have also been raised that the outputs from the model are difficult to interpret within a regulatory context (Merrington et al. 2016). Acknowledging the problem, several authors have proposed simplifications in the input parameters to facilitate the regulatory implementation of BLMs (e.g.Peters et al. 2011; Verschooret al. 2012), that have resulted in the development of user-friendly tools (Biomet 2015; PNEC.pro 2013, M-BAT 2014). A review of these simplified models,including a comparison of their predictive availability against full BLMs calculations can be found in Vink et al. (2010), Rüdelet al.(2015), and Peters et al. (2016).

1. General objective of the task

The task is aiming at delivering practical advice on the implementation of“generic” or “bioavailable” EQSsfor nickel Ni) and lead (Pb) that are representative of high-bioavailability conditions. River basin specific pollutants (RBSP) common to many Member States, such as copper (Cu) and zinc (Zn), will also be considered. More specifically, this task will address issues related to:

-the selection and application of Biotic Ligand Models (BLMs) and freely-available user-friendly tools (Bio-met, PNEC.pro, M-BAT) on monitoring data, to estimate site-specific bioavailable metal concentrations;

-the derivation and consideration of natural background reference concentrations for metals;

-thedevelopment and the implementation of a tiered-approach for assessing compliance with generic EQSs (i.e. surface water classification).

Taking into consideration past efforts to promote best practice to account for metal bioavailability and meet the challenges of the implementation of bioavailability-based EQSs (WCA, 2015),and drawing on the knowledge and experience gained from national initiatives (e.g. Verschooret al. 2011; Hommen and Rüdel 2012; Tack 2012; WFD-UKTAG 2014; Hoppe et al. 2015), a guidance document will be developed,primarily focusing on continental surface water bodies (rivers and lakes).

A hands-on workshop on friendly-user tools will also be organised through this activity. Among other things, results from the workshop should help those Member States that have not developed their own simplified models select one of the three user-friendly tools freely available to perform their assessments.

Finally, some of the key remaining challenges to the implementation of bioavailability-based approaches under the WFD will be acknowledged in the document.

1. Specific objectives

Examination of the responses to comments document (RCOM) accompanying therecent WCA guidance (WCA 2015), and identification of major points of contention.

Review of existing biotic ligand models, scientific principles behind BLMs anduncertainties associated with different specific implementation approaches. Review of simplified (development and application), user-friendly tools, level of accuracy in the model predictions and operating boundaries.

Inventory of problems commonly encountered when using friendly-user tools on real monitoring data:

-What to do with non-detects?

-What if data for some input parameters are absent?

-What if input parameters fall outside the validated/operating ranges of the models?

-When and how to take into account naturalbackground levels when assessing compliance?

-What to do when water chemistry conditions vary markedly both in space (from the upstream part to downstream) and time?

-What about MACs?

-Etc.

Address the problem of bioavailability-based EQS derivation for river basin specific pollutants (Cu and Zn), and the identification of most sensitive conditions at a river basin scale.

Inventory of theAssess existing and proposedmethods to determine natural background reference concentrations for metals in surface waters: percentile of the distribution of monitoring data, clean stream approach, sediment approach, etc.(seeOstéet al. 2011; Peters et al. 2012; Ostéet al. 2013; Chandesriset al. 2013).

Organisation of a workshop on the friendly-user tools that are freely available (M-BAT, Bio-met and PNEC.pro):

-Facilitate the understanding of the concepts of bioavailability. Provide the skills and tools to be able to use monitoring data to perform bioavailability-based risk and compliance assessment for trace metals;

-Answer the queries of Member States in regard to the selection of one of the three user-friendly tools.

1. Deliverables

Results from this activity include:

-CIS guidance document on the implementation of “generic”or bioavailability-based EQSs for metals, including recommendations on the use of biotic ligand models to predict bioavailable metal concentrations (or site specific EQSs) and the consideration of naturalbackground concentrations in view of assessing the chemical status of surface water bodies;

-Workshop on the use of user-friendly tools that are freely available to account for metal bioavailability. The workshop will cover key scientific concepts around bioavailability and through practical exercises participants will undertake local risk assessment and regulatory compliance. Full chronic BLMs (Ni, Zn, and Cu) will be used on real monitoring data to estimate exposure concentrations, and results will be tested against the predictions fromeach of the three simplified models (Bio-met, PNEC.pro, M-BAT) to evaluate their performance under various conditions.

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Draft version, 23rd November 2016

1. Project work plan

Task Name / 2016 / 2017 / 2018
M11 / M12 / M1 / M2 / M3 / M4 / M5 / M6 / M7 / M8 / M9 / M10 / M11 / M12 / M1 / M2

1. Literature search, collating existing documents (reports and peer-reviewed articles)

1. Preparation of the ToR, circulationamong members of WG-Chemicals for comments , revised version of the ToR

1. Call for interest, set up of a drafting group

1. Drafting group kick-off meeting (purpose and scope of the guidance, contents and identification of possible contributions)

1. Writing and mergingthe sections, editing the first draft and sending to the group for comments

1. Preparation of a workshop on user-friendly tools to predict bioavailability (“hands-on” with Bio-met, PNEC.pro and M-BAT)

1. Drafting group second meeting, review comments

1. Preparation of the second draft

1. Workshop on user-friendly tools

1. External review of the draft guidance, final version

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Draft version, 23rd November 2016

1. Drafting group members

France, The Netherlands (activity chairs)

Austria, Germany, Denmark, The UK, Romania, Sweden, Eurométaux, DG ENV (contributors)

The ways of working will include teleconferences, email exchanges, and the creation of a SharePoint site for the activity. Additional experts will be involved in the task for some specific issues. WCA and Deltaresare already proposed as possible contributors to this activity (notably as developers of user-friendly tools).

1. References

Metal bioavailability

Bio-met. 2015. Bioavailability of metals and the Water Framework Directive. Available from:

Campbell PGC. 1995. Interactions between trace metals and aquatic organisms: a critique of the free-ion activity model. In: Tessier A, Turner DR (eds) Metal speciation and bioavailability in aquatic systems. John Wiley and Sons, New York, pp. 45-102.

Copper RAR. 2008. Voluntary risk assessment reports – copper and copper compounds. European copper institute, Brussels, Belgium.

European Commission. 2013. Directive 2013/39/EU of the European Parliament and of the Council of 12 August 2013 amending Directives 2000/60/EC and 2008/105/CE as regards priority substances in the field of water policy. Official Journal of the European Union, L 226/1. Brussels, Belgium.

Hommen U, Rüdel H. 2012.Sensitivity analysis of existing concepts for application of biotic ligand models (BLM) for the derivation and application of environmental quality standards for metals and evaluation of the approaches with appropriate monitoring data sets from German waters. Fraunhofer Institute for Molecular Biology and Applied Ecology, Schmallenberg. Report produced on behalf of the Umweltbundesamt (FKZ 363 01 352).

Hoppe S, Sundbom M, Borg H, Breitholtz M, 2015.Predictions of Cu toxicity in three aquatic species using bioavailability tools in four Swedish soft freshwaters.Environ. Sci. Eur. 27:25.

M-BAT. 2014. Metal bioavailability assessment tool (version 30.0, November 2013). Available from

Merrington G, Peters A, Schlekat CE. 2016.Accounting for metal bioavailability in assessing water quality: A step change? Environ. Toxicol. Chem. 35(2): 257-265.

Nickel EU RAR. 2008. European Union risk assessment report – nickel and nickel compounds. The Office for Official Publications of the European Communities, Luxembourg.

Niyogi S, Wood CM. 2004.Biotic ligand model, a flexible tool for developing site-specific water quality guidelines for metals.Environ. Sci. Technol. 38(23): 6177-6192.

Nys C, Janssen CR, Van Sprang P, de Schamphelaere KAC. 2016. The effect of pH on chronic aquatic nickel toxicity is dependent on the pH itself: extending the chronic nickel bioavailability models. Environ. Toxicol. Chem. 35(5): 1097-1106.

PaquinPR, Gorsuch JW, et al. 2002. The biotic ligand model: a historical overview. Comp. Biochem. Physiol. C 133: 3-35.

Peters A, Merrington G, de Schamphelaere K, Delbeke K. 2011. Regulatory consideration of bioavailability for metals: simplification of input parameters for the chronic copper biotic ligand model. Integr. Environ. Assess. Manag.7(3): 437-444.

Peters A, Schlekat CE, Merrington G. 2016. Does the scientific underpinning of regulatory tools to estimate bioavailability of nickel in freshwaters matter? The European-wide environmental quality standard for nickel.Environ. Toxicol. Chem. 35(10): 2397-2404.

PNEC.pro. 2013. PNEC.pro bioavailability tool (version 5, June 2013). Available from:

Rüdel H, Diaz Muniz C, Garelick H, Kandile NG, Miller BW, Pantoja Munoz L, Peijnenburg WJGM, Purchase D, Shevah Y, van Sprang P, Vijver M, Vink JPM. 2015. Consideration of the bioavailability of metal/metalloid species in freshwaters: Experiences regarding the implementation of biotic ligand model-based approaches in risk assessment frameworks. Environ. Sci. Pollut. Res. 22: 7405-7421.

SCHER. 2010. Opinion of the chemicals and the Water Framework Directive: Technical guidance for deriving environmental quality standards; Scientific Committee on Health and Environmental Risks (SCHER). October 2010.

Tack K. 2012. Prise en compte de la biodisponibilité des métaux selon la DCE. INERIS report DRC-12-126834-07511A, Verneuil-en-Halatte, France.

Verschoor AJ, Vink JPM, de Snoo GR, Vijver MG. 2011. Spatial and temporal variation of watertype-specific no-effect concentrations and risks of Cu, Ni, and Zn. Environ. Sci. Technol. 45:6049-6056.

Verschoor AJ, Vink JPM, Vijver MG. 2012. Simplification of biotic ligand models of Cu, Ni, and Zn by 1-, 2-, and 3-Parameter transfer functions. Integr. Environ. Assess. Manag. 8(4): 738-748.

Vink JPM, Verschoor A. 2010. Biotic ligand models: availability, performance and applicability for water quality assessment. Deltares report 1203842, Utrecht, The Netherlands.

WCA. 2015. Technical guidance to implementing bioavailability based environmental quality standards for metals. Eurometaux, Brussels.

WFD-UKTAG. 2014. Guide to the metal bioavailability assessment tool (M-BAT) – Water Framework Directive: River and Lake. WFD-UKTAG, Stirling, Scotland.

Zinc EU RAR. 2010. European Union risk assessment report – zinc metal. The Office for Official Publications of the European Communities, Luxembourg.

Background reference concentrations for metals

Chandesris A, Canal J, Bougon N, Coquery M. 2013. Détermination du fond géochimique pour les métaux dissous dans les eaux continentales. Rapport Irstea, Villeurbanne, France.

Osté LA, Klein J, Zwolsman GJ. 2011. Inventory and evaluation of methods to derive natural background concentrations of trace metals in surface water, and application of two methods in a case study. Deltares report 1206111.005, Utrecht, The Netherlands.

Osté LA. 2013. Derivation of dissolved background concentrations in Dutch surface water based on a 10th percentile of monitoring data. Deltares report 1206111.005-2, Utrecht, The Netherlands.

Peters A, Merrington G, Crane M. 2012. Estimation of background reference concentrations for metals in UK freshwaters.WFD-UKTAG; Edinburgh, Scotland.

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[1]In 2007, the US EPA established a freshwater quality criterion for Cu based on the Cu BLM, but adoption of the federal approach at the state level has been relatively slow (Merrington et al. 2016).

[2] This approach has been used to derive bioavailability-based environmental quality standards under the WFD.