Hydrocarbons, C12-C15, n-alkanes, isoalkanes, cyclics, < 2% aromatics

Toxicity to terrestrial plants

Administrative data

Endpoint:

toxicity to terrestrial plants: 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 modelling 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 substance are within the scope of the TLM and EqP frameworks.

Data source

Reference

Reference 1

Reference Type:

publication

Title:

Refinement and validation of TLM-derived HC5 values. Independent review.

Author:

McGrath JA, Di Toro DM, Fanelli CJ

Year:

2015

Bibliographic source:

HDR, Mahwah, NJ

Reference 2

Reference Type:

publication

Title:

Unnamed

Year:

1991

Reference 3

Reference Type:

publication

Title:

Extension and validation of the target lipid model for deriving predicted no-effect concentrations for soils and sediments

Author:

Redman AD, Parkerton TF, Paumen ML, McGrath JA, den Haan K, DiToro DM

Year:

2014

Bibliographic source:

Envrionmental Toxicology and Chemistry Vol. 33, No. 12, pp. 2679-2687 (2014)

Materials and methods

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 material

Test material information

Constituent 1

Reference substance name:

Hydrocarbons, C12-C15, n-alkanes, isoalkanes, cyclics, <2% aromatics

EC Number:

920-107-4

Molecular formula:

C12H22 to C15H32

IUPAC Name:

Hydrocarbons, C12-C15, n-alkanes, isoalkanes, cyclics, <2% aromatics

Details on test material:

Hydrocarbons, C12-C15, containing n-alkanes, isoalkanes, and cyclics with less than 2% aromatics

Test organisms

1

Species:

Avena sativa

Plant group:

Monocotyledonae (monocots)

2

Species:

Brassica rapa

Plant group:

Dicotyledonae (dicots)

Results and discussion

Effect concentrations

Effect concentrations 1

Species:

Avena sativa

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

>= 15 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

seedling emergence

Effect concentrations 2

Species:

Avena sativa

Duration:

28 d

Dose descriptor:

EC10

Effect conc.:

2 969 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth

Remarks on result:

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

Effect concentrations 3

Species:

Brassica rapa

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

9 900 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

seedling emergence

Effect concentrations 4

Species:

Brassica rapa

Duration:

28 d

Dose descriptor:

EC10

Effect conc.:

1 897 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth

Remarks on result:

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

Applicant's summary and conclusion

Conclusions:

The Hydrocarbons, C12-C15, n-alkanes, isoalkanes, cyclics <2% aromatics estimated 14-day LC50 values is >15,000 mg/kg based on seedling emergence and the 21-day EC10 value is >2,969 mg/kg dw based on growth for the terrestrial plant monocot species Avena sativa.

The Hydrocarbons, C12-C15, n-alkanes, isoalkanes, cyclics <2% aromatics estimated 14-day LC50 values is > 9,000mg/kg based on seedling emergence and the 21-day EC10 value is 1,897 mg/kg dw based on growth terrestrial plant dicot species Brassica rapa.

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.