Project Details Consideration of bioavailability of metals/metal compounds in the aquatic environment

Project No.:
Start Date:
01 January 2012
End Date:
30 September 2017
Division Name:
Chemistry and the Environment Division
Division No.:


Research has demonstrated total metal(loid) concentrations are not the most appropriate variables for risk assessment of metal(loid)s toxicity. There is increasing acknowledgment that quantification of the bioavailable fractions of metal(loid)s are better variables for risk assessment by different regulatory bodies in the USA and Europe. One approach are Biotic Ligand Models (BLM) which employ site specific assessments of metal(loid) risks by considering environmental factors influencing dissolved metals interaction in the aquatic environment and with different organisms (dissolved organic carbon, hardness). This project’s objectives is to review existing approaches, identify opportunities (site specific assessments) and possible shortcomings (boundaries of validity), and investigate harmonization potentials.


Biotic Ligand Models (BLM) reflect the latest scientific knowledge on metals speciation and bioavailability and are used in several countries for risk assessment and management. BLM applications are currently available for a limited number of metals (e.g., copper and zinc) for aquatic environments. The US EPA updated its national recommended aquatic life criteria for copper incorporating the use of the BLM in the criteria derivation. In Europe, the REACh regulation (Registration, Evaluation, Authorization and Restriction of Chemicals) allows the use of BLM for deriving region-specific PNEC (predicted no effect concentrations), e.g. depending on regional water conditions. For the European Water Framework Directive (WFD) a recently launched guidance document encourages the derivation of BLM based environmental quality standards (EQS) for priority metals and metal compounds to allow compliance checking for specific local situations. Within this IUPAC project implemented regulatory approaches considering BLM and US EPA approaches will be reviewed. A general assessment will be performed to characterize advantages and possible drawbacks in comparison to traditional approaches (e.g. generic quality criteria, hardness banding, cost associated with regulations and sampling). Similarities of BLM approaches in regulations will be identified and differences discussed. Especially the adaption to possible shortcomings (e.g., boundaries of validity, limited number of species for which chronic BLM are available) will be evaluated and harmonization potential described. Results will be presented to stakeholders (regulators, industry, researchers) and discussed at workshops in Europe and N. America followed by a webinar. Final product for dissemination will be a guidance document for the appropriate use of bioavailability concepts in regulatory environments.


Sep 2013 update – There was a face to face meeting in Berlin in May 2012 where the comments of the project reviewers were discussed and a project timeline was agreed upon. During the following two conference calls (July 2012, May 2013) the project was discussed and the timeline for the first milestone was agreed upon.

Sep 2015 update – In February 2015 the group submitted the revised version on the manuscript on metal bioavailability to the peer-reviewed Springer journal Environ Sci Poll Res (2015) 22, 7405-7421; (published online on March 8, 2015 )

The task group will continue to work on how to disseminate the project outcomes.

Oct 2017 – As further dissemination approach a website was established which provides basic information on metal bioavailability (based on the paper) and supports the application of bioavailability tools (by provision of information on and links to respective software tools):

project completed

Last updated 13 Oct 2017