P Van Sprang

Environmental risk assessment of zinc in European freshwaters: A critical appraisal

A risk assessment report (RAR) on zinc and zinc compounds has recently been prepared in the framework of the European Union (EU) Council Regulation 793/93/EEC on Existing Chemicals. The EU Scientific Committee on Human and Environmental Risks (SCHER) has, however, expressed some fundamental, science-based concerns about the approach followed and the conclusions. The main objective of the present study was to assess the potential environmental risks associated with current use patterns of Zn in nine EU river basins in Germany, France and Belgium, thereby using more advanced methodologies which are largely in line with the recommendations made by SCHER. This included (i) avoiding working with measured Zn concentrations from monitoring stations that were potentially influenced by point sources and/or historical contamination, (ii) the full bioavailability normalization of all chronic ecotoxicity data to river basin specific physico-chemistry using biotic ligand models (BLM), prior to deriving predicted no effect concentrations (PNEC) with the species sensitivity distribution (SSD) approach, and (iii) the use of a probabilistic framework for risk characterization. Further, a total risk approach instead of an added risk approach was used, and the PNEC was equated to the HC5-50 without an additional assessment factor. Based on monitoring data we estimated predicted environmental concentrations (PEC) for the different EU river basins between 1.3 and 14.6 microg dissolved Zn/L. PNEC values varied between 22.1 and 46.1 microg dissolved Zn/L. This resulted in deterministic risk characterization ratios (RCR) that were below 1 in all river basins, suggesting that there is no deterministic regional risk associated with current use patterns of Zn in these river basins. With the probabilistic approach we identified rather limited risks, i.e., between <0.4 and 18.3%. When the EU RAR approach was applied to the same monitoring datasets, deterministic risks were found in different river basins. A detailed analysis showed that this different deterministic conclusion of risk is mainly due to the fact that the EU RAR (i) uses an additional assessment factor of 2 to derive the PNEC and (ii) uses a more conservative approach for implementing bioavailability (BioF approach). We argue that the larger conservatism in the EU RAR mainly originates from decisions made to deal in a pragmatic way with (i) uncertainty related to the across-species extrapolation of BLMs and (ii) the relatively high sensitivity of some multi-species toxicity studies.

Uncertainties in the Environmental Risk Assessment of Metals

As life has evolved in the presence of metals, the assessment of the potential adverse effects of metals on ecosystems requires a different approach than those presently used for man-made organic substances. This article provides a brief review of applications and limitations of current techniques and presents, based on recent research results, suggestions for improving the scientific relevance and accuracy of environmental risk assessments of metals. The importance of the following factors responsible for major uncertainties in current environmental risk assessments of metals are discussed: factors affecting metal bioavailability and toxicity, the potential importance of deficiency effects (for essential metals), and field extrapolation of laboratory toxicity data. Possible (regulatory) consequences of inaccurately assessing the natural background concentrations of metals and acclimatization/adaptation potential of laboratory organisms and resident communities are illustrated using examples of recent research, hypothesis development, and a probabilistic environmental risk assessment.

Simulation of Spatial and Temporal Variability of Chronic Copper Toxicity to Daphnia magna and Pseudokirchneriella subcapitata in Swedish and British Surface Waters

ABSTRACT Water Quality Criteria (WQC) for metals are usually based on single species laboratory toxicity data. The influence of water characteristics of the surface waters on bioavailability to freshwater organisms is hence neglected, along with regional and temporal variability of these water characteristics. A methodology is presented to account for regional and temporal variability in the WQC setting for copper in the United Kingdom and Sweden. Bioavailability models were applied in a Monte-Carlo approach to account for temporal variability and a Geographic Information System was used to account for geographical variability on the chronic copper toxicity to Daphnia magna and Pseudokirchneriella subcapitata. Fifth percentiles of distributions of the No Observed Effect Concentration (NOEC) for both model species were derived in both study regions. For P. subcapitata, it was demonstrated that this fifth percentile can vary by a factor 10 in the UK study region. The ratio of these NOEC fifth percentiles (D. magna percentile divided by P. subcapitata percentile) was used to compare the ecotoxicity of copper to two model species. This ratio showed the highest variability (a factor 5) within the Swedish study region. The findings of this research stress the need for the use of region-specific WQC for copper.

A new test system for the evaluation of toxic levels of liposoluble products in the aquatic food chain using Artemia and Mysidopsis bahia as experimental animals

Abstract A new test system is described for the evaluation of toxic levels of liposoluble products in the aquatic food chain using Artemia and Mysidopsis bahia (M.) as experimental animals. For this, freshly released juveniles (≤ 24 h old) of M. bahia are transferred to the experimental bioassay test system, cultured under standard conditions and fed 24 h old purposely contaminated Artemia nauplii. After 11 days, data on survival, reproductive characteristics, individual length and dry weight are recorded and treated statistically.