Hydrocarbons, C6-C7, n-alkanes, isoalkanes, cyclics, <5% n-hexane

Sediment toxicity

Link to relevant study record(s)

Reference

Endpoint:

sediment toxicity: long-term

Type of information:

(Q)SAR

Adequacy of study:

key study

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. The model used for the calculations was the PETROTOX v4.0 model. PETROTOX is a well-documented and peer reviewed model that is widely used across the chemicals industry.

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

Key result

Duration:

28 d

Dose descriptor:

other: LL50

Effect conc.:

191.16 mg/kg sediment dw

Nominal / measured:

estimated

Conc. based on:

other: QSAR prediction

Basis for effect:

mortality

Remarks on result:

other: QSAR predicted value

Key result

Duration:

28 d

Dose descriptor:

other: EL10

Effect conc.:

36.62 mg/kg sediment dw

Nominal / measured:

estimated

Conc. based on:

other: QSAR prediction

Basis for effect:

other: reproduction

Remarks:

biomass

Remarks on result:

other: ACR 5.22 (McGrath et al., 2018)

Remarks:

QSAR predicted value

Details on results:

Chronic endpoints were estimated using typical acute-to-chronic ratio of 5.22 (McGrath et al., 2018).

Validity criteria fulfilled:

yes

Conclusions:

The toxicity of this substance to sediment dwelling organisms has been predicted using the target lipid model (TLM) and HC5, and using the equilibrium partitioning (EqP) model. The predicted 28-d LL50 (mortality) of this substance to Lumbriculus variegatus is 191.16 mg/kg sediment dw and the predicted 28-d EL10 (reproduction/biomass) is 36.62 mg/kg sediment dw.

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. The model used for the calculations was the PETROTOX v4.0 model. PETROTOX is a well-documented and peer reviewed model that is widely used across the chemicals industry.

The predicted 28-d LL50 (mortality) of this substance to Lumbriculus variegatus is 191.16 mg/kg sediment dw and the predicted 28-d EL10 (reproduction/biomass) is 36.62 mg/kg sediment dw.

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. The model used for the calculations was the PETROTOX v4.0 model. PETROTOX is a well-documented and peer reviewed model that is widely used across the chemicals industry.