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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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
GLP compliance:
yes (incl. QA statement)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Duration of test (contact time):
28 d
Initial conc.:
102.5 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Test temperature: 22°C ± 1°C
- pH:
7.5 (measured at the start of the test)
6.5 to 7.5 (measured at the end of the test)
- pH adjusted: no
- Continuous darkness: yes

TEST SYSTEM
- Number of culture flasks/concentration: 2

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2
- Abiotic sterile control: 1
- Toxicity control: 1
Reference substance:
benzoic acid, sodium salt
Parameter:
% degradation (O2 consumption)
Value:
13
Sampling time:
4 d
Remarks on result:
other: based on ThODNO3
Parameter:
% degradation (O2 consumption)
Value:
74
Sampling time:
14 d
Remarks on result:
other: based on ThODNO3
Parameter:
% degradation (O2 consumption)
Value:
81
Sampling time:
28 d
Remarks on result:
other: based on ThODNO3
Details on results:
The 10-day windows began on day 4 after application, the mean value was calculated to be 13% biodegradation (ThODNO3). Therefore, the end of the 10-day window was day 14. The mean biodegradation percentage based on ThODNO3 at the end of the 10-day window was 74%; the criterion of the 10 day window was passed. The mean biodegradation percentage at the end of the 28-day exposure period was 81% (ThODNO3).
In the toxicity control containing both, the test item and the reference item sodium benzoate, 90% (ThODNH4) biodegradation was noted within 14 days and 87% (ThODNH4) biodegradation after 28 days of incubation (73% and 71% based on ThODNO3).
Results with reference substance:
The reference item sodium benzoate was sufficiently degraded to 96% after 14 days and to 101% after 28 days of incubation.
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
N,N’-di-L-alanyl-L-cystine is considered to be readily biodegradable on ThODNH4 and ThODNO3.

Description of key information

In a study following OECD Guideline No. 301 F the biodegradation of N,N’-di-L-alanyl-L-cystine was examined. The mean biodegradation percentage at the end of the 28 -day exposure period was 81% based on ThODNO3 (OECD301F). The mean biodegradation percentage based on ThODNO3 at the end of the 10-day window was 74%; the criterion of the 10 day window was passed.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:
freshwater

Additional information