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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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Report date:
2018

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
Sodium valproate
EC Number:
213-961-8
EC Name:
Sodium valproate
Cas Number:
1069-66-5
Molecular formula:
C8H16O2.Na
IUPAC Name:
sodium 2-propylpentanoate

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
102.7 mg/L
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradationopen allclose all
Parameter:
% degradation (O2 consumption)
Value:
10
Sampling time:
6 d
Key result
Parameter:
% degradation (O2 consumption)
Value:
59
Sampling time:
16 d
Key result
Parameter:
% degradation (O2 consumption)
Value:
68
Sampling time:
28 d
Details on results:
The criterion for ready biodegradability under the conditions of a manometric respirometry test is the degradation of the test item of at least 60%, reached within a 10-day window. At the end of the 10-day window at day 16 the mean degradation of Sodium Valproate was 59% (ThODNH4) and therefore the 10 day window criterion was not passed. The mean biodegradation at test end after 28 days was 68% (ThODNH4).
The degradation rate of Sodium Valproate did not reach 60% within the 10 day window but after 28 days. Therefore, Sodium Valproate is considered biodegradable although failing the 10 day window.

BOD5 / COD results

Results with reference substance:
The reference item sodium benzoate was sufficiently degraded to 84% after 14 days and to 84% after 28 days of incubation, thus confirming the suitability of the aerobic activated sludge inoculum used.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The degradation rate of Sodium Valproate did not reach 60% within the 10-day window but after 28 days.
Therefore, Sodium Valproate is considered biodegradable although failing the 10 day window.