Registration Dossier

Ecotoxicological information

Toxicity to microorganisms

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Administrative data

Endpoint:
activated sludge respiration inhibition testing
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 mixture whose constituents within the mixture 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 framework was validated previously for acute and chronic aquatic toxicity endpoints. The constituents in this substance are within the scope of the TLM and EqP frameworks.

Data source

Reference
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

Materials and methods

Principles of method if other than guideline:
The target lipid model (2015) as described in the cited reference was used to determine aquatic 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

Reference
Name:
Unnamed
Specific details on test material used for the study:
The registered substance is a UVCB substance consisting of a number of hydrocarbon and oxygenated hydrocarbon components, covering a wide range of carbon numbers and structures. The relevant components were determined based on the best available analytical data and process knowledge (see dossier sections 1.2 Composition and 1.4 Analytical methods). The representative structures and relative mass balance for each group of constituents are presented in the attached document.

Results and discussion

Effect concentrations
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
8.9 mg/L
Nominal / measured:
nominal
Basis for effect:
inhibition of total respiration

Applicant's summary and conclusion

Conclusions:
(Q)SAR estimations for the registered substance resulted in an EC50 of 8.9 mg/L for Tetrahymena elliotti.
Executive summary:

The registered substance is a complex mixture whose constituents within the mixture 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) has been applied to aquatic toxicity and is considered fit for purpose.