The toxicity of molybdate to freshwater and marine organisms. II. Effects assessment of molybdate in the aquatic environment under REACH

• Published in: The Science of the total environment Vol. 435-436; pp. 179 - 187
• Main Authors: Heijerick, D.G., Regoli, L., Carey, S.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.10.2012
• Subjects: Amphibians; Animals; Aquatic Organisms; Assessments; bioaccumulation; biogeography; Compartments; Derivation; ecotoxicology; Environmental Protection Agency; Fishes; freshwater; Freshwater assessment; Freshwaters; Geologic Sediments; Insecta; Marine; Marine assessment; marine environment; Marine environments; marine sediments; Mollusca; Molybdate; Molybdenum; Molybdenum - analysis; Molybdenum - toxicity; No-Observed-Adverse-Effect Level; PNEC derivation; research programs; toxicity; Toxicity Tests, Chronic - methods; uncertainty analysis; Water Pollutants, Chemical - analysis; Water Pollutants, Chemical - toxicity; Water Pollution, Chemical - adverse effects; Water Pollution, Chemical - legislation & jurisprudence; PNEC derivation; Molybdate; Marine assessment; Freshwater assessment
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2012.05.075

The REACH Molybdenum Consortium initiated an extensive research program in order to generate robust PNECs, based on the SSD approach, for both the freshwater and marine environments. This activity was part of the REACH dossier preparation and to form the basis for scientific dialogues with other national and international regulatory authorities. Chronic ecotoxicity data sets for the freshwater and marine environments served as starting point for the derivation of PNECs for both compartments, in accordance with the recommended derivation procedures established by the European Chemicals Agency (ECHA). The HC5,50%s that were derived from the generated Species Sensitivity Distributions were 38.2mgMo/L and 5.75mgMo/L for the freshwater and marine water compartment, respectively. Uncertainty analysis on both data sets and available data on bioaccumulation at high exposure levels justified an assessment factor of 3 on both HC5,50% leading to a PNECfreshwater of 12.7mgMo/L and a PNECmarine of 1.92mgMo/L. As there are currently insufficient ecotoxicological data available for the derivation of PNECs in the sediment compartment, the equilibrium partitioning method was applied; typical KD-values for both the freshwater and marine compartments were identified and combined with the respective PNEC, leading to a PNECsediment of 22,600mg/kg dry weight and 1980mg/kg dry weight for freshwater and marine sediments, respectively. The chronic data sets were also used for the derivation of final chronic values using the procedures that are outlined by the US Environmental Protection Agency for deriving such water benchmarks. Comparing PNECs with FCVs showed that both methodologies result in comparable protective concentration levels for molybdenum in the environment. ► Derivation of freshwater and marine safe levels based on chronic ecotoxicity data. ► PNEC derivation according to EU guidance, using the statistical extrapolation. ► Determination of a Final Chronic Value according to US EPA guidance. ► Similarity between the outcome of the EU and US approach for setting WQC.