Although there is already huge scientific evidence for the influence of water chemistry on metal toxicity, only few regulations have implemented bioavailability approaches. Recently, the BLM concept has gained interest from the academic, industrial, and regulatory communities since BLMs reflect the latest scientific knowledge on metal toxicity and integrate metal speciation, accumulation, effects, and physiology. Moreover, user-friendly BLM-based bioavailability tools are available now which can be applied by non-BLM expert water managers and environmental risk assessors.
Still BLMs are only available for a limited number of metals (e.g., Cu, Ni, Zn, or Ag). In 2007, the United States Environmental Protection Agency (US EPA) recommended that aquatic life criteria incorporate the use of a BLM, but only for Cu and only in freshwater (link). In Europe, some countries (e.g., UK, France, Sweden) tested the use of BLM-based bioavailability tools for deriving region-specific predicted no effect concentrations (PNECs) by considering regional water conditions. Moreover, a recently launched Water Framework Directive (WFD; 2000/60/EC) guidance document encourages the derivation of BLM-based environmental quality standards (EQSs) for metals to allow compliance checking for specific local situations (link). In a recently released revision of the WFD EQS directive (2013/39/EU) for two metals (Pb, Ni) already EQS based on bioavailable concentrations were enacted.
Consideration of the bioavailability of metal/metalloid species in freshwaters: experiences regarding the implementation of biotic ligand model-based approaches in risk assessment frameworks
Rüdel H, Díaz Muñiz C, Garelick H, Kandile NG, Miller BW, Pantoja Munoz L, Peijnenburg WJ, Purchase D, Shevah Y, van Sprang P, Vijver M, Vink JP
Environ Sci Pollut Res Int (2015) 22, 7405-7421
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