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Ecotoxicological information

Sediment toxicity

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Description of key information

The freshwater sediment effect records include 62 high quality single-species chronic NOEC/L(E) C10 values from 6 different different sediment- dwelling species of relevance to setting the freshwater aerobic sediment PNEC in a WOE approach.

Considering the importance of bio-availability for reducing the intra-species variability, the data- base includes supportive information related to the development/validation of the sediment organic carbon normalization. The NOECS and OC normalization model are used for the aerobic sediment PNEC derivation. Information in support of the protective effect of sediment sulphides is useful to the risk characterization.

Key value for chemical safety assessment

Additional information

Freshwater sediment NOECS

The high quality records retained for the PNEC derivation of copper under the Existing Substances Regulation (TCNES) and Biocidal Products regulations (Technical meetings) have been included in the IUCLID data-base. Tests that were considered as not-reliable for the PNEC derivations have NOT been included in the IUCLID records but have been summarized in the copper RA report (2008).

 106 high quality chronic NOEC/(L(E) C10 values are available for 6 different sediment- dwelling organisms. the amphipodsHyalella aztecaandGammarus pulex, the oligochaetesTubifex tubifexandLumbriculus variegatus, the insectChironomus ripariusand the insectHexagenia.

The Individual NOEC values range between 18.3 mg/kg dry weight and >3,158 mg/kg (min-max value). Large intra-species variability are observed due to variations in organic carbon (OC) content and acid volatile sulphide (AVS) content of the sediments (De Schamphelaere et al.,2005). Normalization of the NOECs/(L(E) C10 for OC was demonstrated. Normalization of the effects data for AVS was not possible and therefore only NOEC/(L(E) C10 values generated under conditions that represent “aerobic” conditions (Low AVS) were considered as adequate for the PNEC derivation. Effects data from studies with AVS concentration lower than the 10th percentile of the AVS concentration (i. e. 0.77 mmol/kg dry weight) were thus retained. Using this exclusion rule, the original dataset containing 106 NOEC values was reduced to a trimmed data set of 62 NOEC values for copper.

The data base includes additional information in support of the importance if AVS binding in the field (Boothman et al., 2001) and demonstrating the lesser sensitivity of algae in the biofilm compared to free living algae(Barranguet et al., 2000)and the applicability of long term benthic studies to the life cycle (Pasteris et al., 2003).

The records related to effects observed in freshwater mesocosm studies (multi-species, covering water and sediment) are included in section 6.6. (additional ecotoxicological information). Copper threshold values from three high quality mesocosm studies, representing lotic and lentic systems are available.

Sediment PNEC derivation

For the freshwater PNEC derivation, a weight of evidence approach is applied , using the information from the different environmental compartments: (1) using the freshwater PNEC in an equilibrium partitioning approach; (2) using the high quality freshwater sediment NOECS and (3) comparison with soil NOECS

For the estuarine and marine PNEC derivations, the equilibrium partitioning approach is used

Summaries on the sediment PNEC derivations are provides as attachments