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Ecotoxicological information

Short-term toxicity to aquatic invertebrates

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Administrative data

Endpoint:
short-term toxicity to aquatic invertebrates
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:
Non-testing data acc. to R.7b of the Endpoint specific guidance (Version 4.0, June 2017)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2021
Report date:
2021

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Principles of method if other than guideline:
Nonlinear QSAR model for short term toxicity of invertebrates
GLP compliance:
no
Remarks:
QSAR-method

Test material

Constituent 1
Chemical structure
Reference substance name:
4-chlorobenzoic acid
EC Number:
200-805-9
EC Name:
4-chlorobenzoic acid
Cas Number:
74-11-3
Molecular formula:
C7H5ClO2
IUPAC Name:
4-chlorobenzoic acid

Test organisms

Test organisms (species):
Daphnia magna

Results and discussion

Effect concentrations
Key result
Duration:
48 h
Dose descriptor:
LC50
Effect conc.:
7.64 mg/L
Basis for effect:
mobility

Any other information on results incl. tables

The source experimental data for the model originate from different labs and different experiment series, as they are represented in the US EPA database, adding to uncertainty, however, careful data analysis, previous (and present) successful modeling add to the consistence of the data. The significant dataset size (~300) statistical quality (RMS, correlation coefficients etc.) of the model supports reliable predictions within the margins of the experimental error. The similarity of the analogues together with the correct estimates supports potential prediction consistency.

Considering the dataset size, model statistical quality and prediction reliability, a reliability score (Klimisch score) “2” could be assigned to the present prediction.

The prediction reliability is estimated as 85 %.

Applicant's summary and conclusion

Validity criteria fulfilled:
not applicable
Conclusions:
The calculated LC50 for p-chlorobenzoic acid is 7.64 mg/L for daphnia magna acc. to a QSAR calculation via nonlinear QSAR (ANN) assessment.
Executive summary:

In a nonlinear QSAR (ANN) assessment the short-term toxicity of p-chlorobenzoic acid to daphnia magna was calculated.

All descriptor values for p-chlorobenzoic acid fall in the applicability domain. p-Chlorobenzoic acid is structurally relatively similar to the model compounds. The training set contains compounds of similar size to the studied molecule. p-Chlorobenzoic acid is considered to be in the same mechanistic domain as the molecules in the training set as it is structurally similar to the model compounds. p-Chlorobenzoic acid is considered to be in the same metabolic domain as the molecules in the training set of the model due to the structural similarity.

The experimental acute toxicity values for compounds of similar functionalities are somewhat scattered in the toxicity scales depending on the molecular size and other functionalities. The structural analogues are relatively similar to the studied compound, covering all the chemical features. The descriptor values of the analogues are close to those of the studied compound. The analogues are considered to be within the same mechanistic domain. All the analogues are very well estimated within the model.

The following aspects have been considered for the selection and analysis

of structural analogues:

Presence and number of common functional groups;

Presence and relevance of non-common functional groups;

Similarity of the ‘core structure’ apart from the (non-)common functional groups;

Potential differences due to reactivity;

Potential differences due to steric hindrance;

Presence of structural alerts;

Position of the double bonds;

Presence of stereoisomers.

The source experimental data for the model originate from different labs and different experiment series, as they are represented in the US EPA database, adding to uncertainty, however, careful data analysis, previous (and present) successful modeling add to the consistence of the data. The significant dataset size (~300) statistical quality (RMS, correlation coefficients etc.) of the model supports reliable predictions within the margins of the experimental error. The similarity of the analogues together with the correct estimates supports potential prediction consistency.

Considering the dataset size, model statistical quality and prediction reliability, a reliability score (Klimisch score) “2” could be assigned to the present prediction.

The prediction reliability is estimated as 85%.

The calculated LC50 for p-chlorobenzoic acid is 7.64 mg/L for daphnia magna. Considering the above, the predicted result can be considered adequate for the regulatory conclusion.