Registration Dossier

Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study according to international accepted guidelines but not GLP compliant.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013
Report Date:
2013

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
EU Method C.6 (Degradation: Chemical Oxygen Demand)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.5 (Degradation: Biochemical Oxygen Demand)
Deviations:
no
Qualifier:
according to
Guideline:
other: Guidence on the Application of the CLP Criteria
Deviations:
no
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: crystalline
Details on test material:
Test item: 2,3-dichlorobenzoic acid (CAS: 50-45-3)
Batch No.: L2A134N
Physical state: Solid, crystalline powder
Colour: White
Active ingredient content (titrimetry): 100.4%
Storage: 15-30°C, protected from moisture

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
250.0 ml inoculum culture with 1.0 g/l dry substance concentration was made by diluting an appropriate part of stock culture with aerated tap water.
Duration of test (contact time):
5 d
Initial test substance concentration
Initial conc.:
125 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
other: Pressure (The liberated carbon dioxide is absorbed by sodium hydroxide so the biological oxidation generates vacuum which is registered by the measuring heads.)
Details on study design:
This study was performed to evaluate the degradability of test substance in an aerobic mixed bacterial culture on the base of quotient of biochemical oxygen demand (BOD) and chemical oxygen demand (COD). The test was carried out in three steps. The degradability was calculated from the quotient of BOD5 and COD according to Guidence on the Application of the CLP Criteria.

For the test solution 250.0 mg of test item was solved in 2 000 ml aerated tap water so that the nominal concentration was 125.0 mg/l (used for both COD and BOD5).
The chemical oxygen demand (COD) was determined by the standard dichromate method. Three replicates were measured in the test.
The biochemical oxygen demand (BOD5) of test item was determined by the OxiTop® system. In this test the test solutions are inoculated with mixed aerobe bacterial culture and poured into 500 ml dark glass bottles. The test duration was 5 days. The tightly closed test vessels were kept in incubator at 20 ± 2 °C with continuous stirring. N-Allylthiourea is added to each test vessel for inhibiting of nitrification.

Results and discussion

% Degradationopen allclose all
Parameter:
other: values of vacuum
Value:
3.7
Sampling time:
1 d
Parameter:
other: values of vacuum
Value:
5.4
Sampling time:
2 d
Parameter:
other: values of vacuum
Value:
6.1
Sampling time:
3 d
Parameter:
other: values of vacuum
Value:
4.8
Sampling time:
4 d
Parameter:
other: values of vacuum
Value:
5.9
Sampling time:
5 d

BOD5 / COD results

BOD5 / CODopen allclose all
Parameter:
COD
Value:
1.382 g O2/g test mat.
Parameter:
BOD5
Value:
0.081 g O2/g test mat.
Parameter:
BOD5*100/COD
Value:
5.9 other: %

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
other: not readily biodegradable
Conclusions:
The BOD(5 days)/COD ratio is less than 0.5. In this Degradability Test for “2,3-Dichlorobenzoic Acid” (CAS No. 50-45-3) the results indicated that the test item is not rapidly degradable in the aquatic environment.