4-chlorobenzoic acid

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: screening test, other

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:

other: OECD 309 Ready Biodegradability (Aerobic Mineralisation in Surface Water - Simulation Biodegradation Test)

Principles of method if other than guideline:

nonlinear ANN QSAR method

GLP compliance:

no

Remarks:

QSAR method

Test material

Test material information

Constituent 1

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

Results and discussion

% Degradation

Key result

Parameter:

half-life in days (QSAR/QSPR)

Value:

14.9

Sampling time:

28 d

Remarks on result:

other: sampling time: not applicable (QSAR calculation)

Any other information on results incl. tables

The source experimental data for the model originate from different labs and different experiment series, adding to uncertainty, however, previous (and present) successful modeling add to the consistence of the data. The significant size of the dataset; the diversity of the structures covering a large parts of the chemical space, and the statistical quality (RMS, correlation coefficients etc.) of the model supports reliable predictions within the margins of the experimental error and the classification scheme used. The relative 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 in terms of the persistence category is estimated as 84 %

Applicant's summary and conclusion

Validity criteria fulfilled:

not applicable

Interpretation of results:

inherently biodegradable

Conclusions:

The calculated the half-life T(0.5) of p-chlorobenzoic acid is 14,9 days acc. to a QSAR calculation via nonlinear QSAR (ANN) assessment. The substance is therefore considered to be moderately persistent to the biotic degradation in water.

Executive summary:

In a nonlinear QSAR (ANN) assessment the half-time of biodegradation for p-chlorobenzoic acid 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 model contains compounds featuring benzene rings, hydroxy-, carbonyl and ether functionalities. 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.

The experimental persistence values for compounds of similar functionalities all fall to the “low persistence” category. The structural analogues are only relatively similar to the studied compound, however, there are also additional compounds in the model containing hydroxy-, carbonyl and ether functionalities. 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 correctly estimated within the model.

The source experimental data for the model originate from different labs and different experiment series, adding to uncertainty, however, previous (and present) successful modeling add to the consistence of the data. The significant size of the dataset; the diversity of the structures covering a large parts of the chemical space, and the statistical quality (RMS, correlation coefficients etc.) of the model supports reliable predictions within the margins of the experimental error and the classification scheme used. The relative similarity of the analogues together with the correct estimates supports potential prediction consistency.

The prediction reliability in terms of the persistence category is estimated as 84%.

The calculated the half-life T(0.5) of p-chlorobenzoic acid is 14,9 days acc. to a QSAR calculation via nonlinear QSAR (ANN) assessment. The substance is therefore considered to be moderately persistent to the biotic degradation in water. Considering the above, the predicted result can be considered adequate for the regulatory conclusion.