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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:
other: GLP and OECD guideline study. Only minor deficiencies not considered to be jeopardising the reliability of the study.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1996
Report Date:
1996

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Physical state: Off-white powder
- Analytical purity: 95% w/w
- Other: water solubility 200 mg / L
test substance inhibitory to microorganisms: No

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
source: sewage treatment plant

sampling site: URL north, UK
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
3 mg/L
Based on:
DOC
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: mineral salts medium
- Additional substrate: no
- Test temperature: 20 +-2°C
- pH: not monitored
- Aeration of dilution water: no data
- Suspended solids concentration: 10% by volume of activated sludge plant secondary effluent
- Other: samples placed on a rotoray shaker during the test period

TEST SYSTEM
- Culturing apparatus: sealed vessels
- Number of culture flasks/concentration: 1 vessel/substance/time point, except on day 28, when 5 vessels for the test substance, reference substance and control are used
- Measuring equipment: Ionic 555 Inorganic Carbon Analyzer
- Test performed in closed vessels due to significant volatility of test substance: No
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradationopen allclose all
Parameter:
% degradation (CO2 evolution)
Value:
13.9
Sampling time:
3 d
Parameter:
% degradation (CO2 evolution)
Value:
19.7
Sampling time:
7 d
Parameter:
% degradation (CO2 evolution)
Value:
99.5
Sampling time:
14 d
Parameter:
% degradation (CO2 evolution)
Value:
101
Sampling time:
28 d
Remarks on result:
other: 95% CL: 94.4-107.6
Details on results:
The test substance achieved complete biodegradation after 28 days and passed the 10 day window criterion of > 60% within 10 days of reaching 10% degradation.

Applicant's summary and conclusion

Interpretation of results:
readily biodegradable
Conclusions:
6 -(Phthalimido)hexanoic acid met the criteria for classification as readily and ultimately biodegradable in this study
Executive summary:

6 -(Phthalimido)hexanoic acid (3.00 mg/l as organic carbon) was incubated with activated sludge for 28 days and biodegradation was calculated by measuring the CO2 development. Sodium benzoate (10.03 mg/l as organic carbon) was used as reference substance and negative control was included in the test. At each timepoint, the CO2 concentration was measured in the vessels headspace and, as dissolved inorganic carbon in the liquid medium. Percentile biodegradation of the samples was calculated by the formula (TICs – TICc/TC)x100, where TICs is the total inorganic carbon measured in the sample, TICc is the total inorganic carbon measured in the concurrent control and TC is the organic carbon added in the sample.