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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Remarks:
DOC Die - Away Test
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1998-09-15 to 1998-10-13
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 A (Ready Biodegradability: DOC Die Away Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.4-A (Determination of the "Ready" Biodegradability - Dissolved Organic Carbon (DOC) Die-Away Test)
GLP compliance:
yes (incl. QA statement)
Remarks:
Swiss GLP
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: TVR 50
- Expiration date of the lot/batch: Sept 2004

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: room temperature
- Solubility of the test substance in the solvent/vehicle: > 80 g/1 [in water]
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
Mixture of polyvalent bacteria collected on September 14, 1998 from the aeration tank of a domestic sewage treatment plant, PRO RHENO Basel communal.

Sludge pretreatment:
The sludge was washed 4 times with tap water and the last time with test medium. An amount corresponding to 3 g dry material per liter (±10%) was mixed with test medium and then aerated until use.
pH value of the activated sludge: 7.0

Bacteria concentration:
26 mg/1 Suspended Solids (SS). The bacteria concentration was obtained by adding 10 ml of the pre-treated sludge (2.6 g/l SS) per 1000 ml test medium.
Duration of test (contact time):
28 d
Initial conc.:
37.5 mg/L
Based on:
DOC
Parameter followed for biodegradation estimation:
DOC removal
Reference substance:
other: D(+)-Glucose
Test performance:
Negative biodégradation values or values above 100 are given as 0% or 100%, respectively. The results expressed in % are given as full number and are mean values which were corrected by the blank control.
Parameter:
% degradation (DOC removal)
Value:
6
Sampling time:
28 d
Details on results:
Points of degradation plot (test substance): 2 % degradation after 1 d 6 % degradation after 3 d 5 % degradation after 7 d 6 % degradation after 10 d 6 % degradation after 14 d 6 % degradation after 21 d 6 % degradation after 28 d
Results with reference substance:
Points of degradation plot (reference substance): 51 % degradation after 1 d 95 % degradation after 3 d 96 % degradation after 7 d 98 % degradation after 10 d 98 % degradation after 14 d 99 % degradation after 21 d 99 % degradation after 28 d

Inhibition control: Biodegradation of the inhibition control after 14 days 50%

Abiotic control: Degradation in the abiotic control after 28 days 8%

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
The biodegradation of FAT 40571/A was determined as 6% after 28 days of incubation and considered as not readily biodegradable.
Executive summary:

Ready Biodegradability of FAT 40571/A was carried out according to OECD 301 A and EU C.4-A Guideline using DOC Die -Away Test. Test system used was a mixture of polyvalent bacteria (activated sludge obtained from a communal wastewater treatment plant) and tested for duration of 28 days.

 

A static test at 20.0 - 22.0°C with test volume 200 ml used and continuously shaken in diffuse daylight. The test concentrations used in this test for test substance37.5 mg/1 DOC while for reference substance37.8 mg/1 DOC.Analysis was done to determine DOC concentrations.

 

Based on the study results, test substancebiodegradation after 28 days 6% while for reference substanceafter 14 days 98%.

 

In conclusion, the biodegradation of FAT 40571/A was determined as 6% after 28 days of incubation. The test substance did not reach the pass level of 70% for ready biodegradability in the DOC Die-Away Test either within the 10-day window or after 28 days of incubation. Therefore, FAT 40571/A cannot be assessed as readily biodegradable.

Description of key information

Reactive Brown 49 is not readily biodegradable in DOC die away test with 6 % biodegradation after 28 days of incubation.


 


Additionally, it is not inherently biodegradable in Zahn-Wellens/EMPA Test.


 


Based on the BOD/COD ratio (0/0.88) which is '0', so considered as not readily biodegradable

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed
Type of water:
freshwater

Additional information

In a key study conducted, ready biodegradability of Reactive Brown 49 was carried out according to OECD 301 A and EU C.4-A Guideline using DOC Die -Away Test. Test system used was a mixture of polyvalent bacteria (activated sludge obtained from a communal wastewater treatment plant) and tested for duration of 28 days. A static test at 20.0 - 22.0°C with test volume 200 ml used and continuously shaken in diffuse daylight. The test concentrations used in this test for test substance37.5 mg/1 DOC while for reference substance37.8 mg/1 DOC.Analysis was done to determine DOC concentrations.


 


Based on the study results, test substancebiodegradation after 28 days 6% while for reference substanceafter 14 days 98%.


 


In conclusion, the biodegradation of Reactive Brown 49 was determined as 6% after 28 days of incubation. The test substance did not reach the pass level of 70% for ready biodegradability in the DOC Die-Away Test eitherwithin the 10-day window or after 28 days of incubation. Therefore, Reactive brown 49 cannot be assessed as readily biodegradable.


 


In supporting studies, under Inherent biodegradability test conditions, the total elimination (regarding adsorption and biodegradation) of the substance after 28 days was 4 %. The substance is not inherently biodegradable.


 


Also, the Biochemical Oxygen Demand experiment gave a BOD5 value of 0 mg O2/g, and therefore the substance is not considered as biodegradable.