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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From October 13th to November 11th, 1993
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Version / remarks:
1992
Qualifier:
according to
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Qualifier:
according to
Guideline:
ISO DIS 9408 (Ultimate Aerobic Biodegradability - Method by Determining the Oxygen Demand in a Closed Respirometer)
Version / remarks:
1991
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Amount used, activated sludge: 15 mg/l (dry weight)
- Origin: municipal wastewater treatment plant Frankfurt/M-Sindlingen
- Preliminary treatment: 7 days with stirring.
- Acclimation state: not acclimated in the laboratory to the substance and the reference substance.
Duration of test (contact time):
28 d
Initial conc.:
153 mg/L
Based on:
test mat.
Initial conc.:
337 mg/L
Based on:
COD
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
COD per 1 g of the test material: 2.35 x 10^3 mg/g (O2). The COD per gram of the sample was determined by directly weighing the sample into the COD reaction vessel.

TEST CONDITIONS
- Composition of medium: in accordance with guidelines.
- Test temperature: 22 ± 1 °C

TEST SYSTEM
- Culturing apparatus: BOD bottles were used as the reaction vessel and incubated in the WTW-BSB device.

CONTROL AND BLANK SYSTEM
- Inoculum blank: conducted under the same conditions, witout test material.
- Toxicity control: included.
Parameter:
% degradation (O2 consumption)
Value:
1 - 5
Sampling time:
28 d
Details on results:
The test item was degraded less than 20 %

TOXICITY CONTROL
Control showed no toxicity at the test concentration.
Results with reference substance:
Oxygen consumption in the reference substance reached more than 60 % of degradation in less than 10 days, after adaptation.

Time (d) Depletion as COD
7 4
14 5
21 5
28 1
   
Interpretation of results:
not readily biodegradable
Conclusions:
The substance is not readily biodegradable.
Executive summary:

The assessment of the readily biodegradability potential of the test item was investigated according to the OECD guideline 301F and according to the EU Method C.4-D.

DOC determinations were made in accordance with DIN standard 38 409 part 3 and COD according to the DIN standard 38 409 part 41 and also the requirements of the Directive EEC 84/449. The degradation analysis was carried out by manometric determination of the oxygen consumption.

The reference compound, attained more than 60 % of degradation within 10 days after adaptation, confirming the suitability of the inoculum and culture conditions.

Test item attained negligable degradation within 28 days and therefore cannot be considered as readily biodegradable under the strict terms and conditions of the OECD Guidelines.

Conclusion

The substance is not readily biodegradable.

Description of key information

Not readily biodegradable.

Key value for chemical safety assessment

Additional information

The substance is a bis-benzoxazole derivative; it is not expected to be ready biodegradable because of its chemical structure and the specific function. Commonly, fluorescent brighteners undergo a primary transformation, i.e. discolourization due to the interrupting the conjugation. Nevertheless, the degradation process involves more steps and take more time.

The available experimental results, confirmed that the substance cannot be reapidly biodegraded. The assessment of the readily biodegradability potential of the test item was investigated according to the OECD guideline 301F and according to the EU Method C.4-D. The test item attained negligable degradation (i.e. 1 - 5 %) within 28 days and therefore cannot be considered as readily biodegradable under the strict terms and conditions of the OECD Guidelines.