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Environmental fate & pathways

Biodegradation in water: screening tests

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Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2001-05-15 - 2001-10-22
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: well-documented GLP study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2001
Report Date:
2001

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 835.3110 (Ready Biodegradability)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
UK GLP Monitoring Authority

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Physical state: liquid
- Lot/batch No.: 128003
- Storage condition of test material: room temperature, in the dark until 31 July 2001, thereafter approximately 4°C, in the dark
- Other: Data relating to the identity, purity and stability of the test material are the responsibility of the Sponsor.

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
sewage, domestic (adaptation not specified)
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
2 mg/L
Based on:
formulation

Results and discussion

% Degradation
Parameter:
% degradation (DOC removal)
Value:
16
Sampling time:
28 d

Any other information on results incl. tables

The mean oxygen depletion in the inoculated control vessels after 28 days was 1.010 mg O2/L and the residual oxygen concentration in the test bottles was greater than 0.50 mg O2/L thereby satisfying the validation criterion given in the OECD Test Guidelines. The difference between the extremes of replicate oxygen depletion values at the end of the test was <20% and hence satisfied the validation criterion given in the OECD Test Guidelines. The test material attained 16% degradation after 28 days and, therefore, cannot be considered as readily biodegradable under the strict terms and conditions of OECD Guideline No 301D. Variation in degradation rates on different sampling days was considered to be due to variation in respiration rates between control and test vessels. Nitrate and nitrite analysis of the test solutions at each sampling occasion confirmed that no significant oxygen consumption as a result of nitrification occurred during the study. Examination of the degradation curve for the toxicity control showed that the toxicity control attained in excess of 25% degradation by day 14 of the study thereby confirming that the test material was not toxic to the sewage treatment micro-organisms used in the study. After 28 days the toxicity control had attained 30% degradation. The standard material, sodium benzoate, attained 74% degradation after 28 days thereby confirming the suitability of the test method and culture conditions.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
inherently biodegradable
Conclusions:
The test material attained 16% degradation after 28 days and therefore cannot be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline 301D.