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Sediment toxicity

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Reference
Endpoint:
sediment toxicity: long-term
Type of information:
(Q)SAR
Adequacy of study:
key study
Study period:
2019
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
Detailed information covering the calculation model, compositional data used as input, validity, applicability and adequacy of the result are in the attached document.

The registered substance is a complex petroleum UVCB whose constituents have variable physicochemical properties. Therefore, a modeling framework is needed to account for the bioavailability of the constituents in the mixture, which was then used to predict the toxicity of the substance as a whole.

The target lipid model (TLM) is a framework that relates toxicity to the physicochemical properties of a nonpolar organic constituent. The TLM, and HC5, have been applied to soils and sediment using equilibrium partitioning (EqP) model. This framework utilizes organic carbon partition coefficients (KOC) to convert aquatic based effect levels (CW) to bulk soil- and sediment-based effect levels. The combined TLM-EqP framework was validated previously for soil and sediment acute and chronic toxicity endpoints. The constituents in this substances are within the scope of the TLM and EqP frameworks.
Principles of method if other than guideline:
The target lipid model (2015) and equilibrium partitioning model as described in the cited references were used to determine soil or sediment effect levels following an estimation of initial loading of the registered substance and its constituents in the substrate. A full explanation of the calculation method is provided in the 'attached justification'.
For model description and justification of QSAR prediction: see fields 'justification for type of information' and 'attached justification'
Test organisms (species):
Lumbriculus variegatus
Duration:
28 d
Dose descriptor:
LC50
Effect conc.:
173 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: based on 5% organic carbon content
Duration:
28 d
Dose descriptor:
EC10
Effect conc.:
33.1 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Remarks:
biomass
Remarks on result:
other: chronic endpoints were estimated using typical acute-to-chronic ratio of 5.22 (McGrath et al., 2018) based on 5% organic carbon content
Executive summary:

The registered substance is a complex petroleum UVCB whose constituents have variable physicochemical properties.Therefore, a modeling framework is needed to account for the bioavailability of the constituents in the mixture, which was then used to predict the toxicity of the substance as a whole. The target lipid model (TLM) and HC5, have been applied to soils and sediment using equilibrium partitioning (EqP) model. As such, modeled data are considered fit for purpose.

Description of key information

The registered substance is a complex petroleum UVCB whose constituents have variable physicochemical properties. Therefore, a modeling framework is needed to account for the bioavailability of the constituents in the mixture, which was then used to predict the toxicity of the substance as a whole. The target lipid model (TLM) and HC5, have been applied to soils and sediment using equilibrium partitioning (EqP) model. As such, modeled data are considered fit for purpose.

Detailed information covering the calculation model, compositional data used as input, validity, applicability and adequacy of the result are attached in section 13.2 of IUCLID.

Key value for chemical safety assessment

Additional information