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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:
weight of evidence
Study period:
22 Sept - 20 Oct 1992
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1993
Report date:
1993

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
GLP compliance:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
Isopropyl palmitate
EC Number:
205-571-1
EC Name:
Isopropyl palmitate
Cas Number:
142-91-6
Molecular formula:
C19H38O2
IUPAC Name:
isopropyl palmitate

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
other: activated sludge plant secondary effluent
Details on inoculum:
- Source of inoculum/activated sludge: Secondary effluent of unacclimatised activated sludge plant at the Unilever Research Laboratory North, Great Britain.
- Preparation of inoculum for exposure: Effluent filtered through Whatman filter paper (541) to remove coarse particulate matter; DOC was reduced by sparging the filtered effluent with nitrogen after prior adjustment of the pH to 6.5
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
9.56 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
- Test temperature: 19-22 °C
- pH: 6.5
- pH adjusted: yes

TEST SYSTEM
- Culturing apparatus: 160 mL hypovials containing 100 mL medium with butyl rubber septums and aluminium crimp seals
- Measuring equipment: Ionics 555 Inorganic Carbon Analyser

SAMPLING
- Sampling frequency: Day 2, 6, 10, 14, 17, 20, 24 and 28
- Sampling method: 1 hypovial per sampling removed and DIC and CO2 measured
Reference substance
Reference substance:
other: benzyl alcohol

Results and discussion

% Degradation
Parameter:
% degradation (CO2 evolution)
Value:
91.3
Sampling time:
28 d
Remarks on result:
other: 88.7-93.8 (95% C.L.)
Details on results:
The test substance degraded by > 60 % within the 10-day time window and is thus regarded as readily biodegradable.

BOD5 / COD results

Results with reference substance:
Benzyl alcohol achieved 99.1% biodegradation in 28 days and the 10-day window was fulfilled.

Any other information on results incl. tables

Biodegradability of the test substance in %:

 

Biodegradability

in %

Day

CAS No. 142-91-6

2

23.2

6

75.5

10

76.0

14

78.1

17

93.4

20

97.3

24

87.1

28

91.3

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable