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Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
11/05/2000 - 08/06/2000
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study according to international guideline (OECD Guideline 301 D) under GLP conditions, validity criteria met.
Cross-referenceopen allclose all
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2000
Report Date:
2000

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)
Deviations:
no
Principles of method if other than guideline:
Not relevant
GLP compliance:
yes
Remarks:
Statement of compliance

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Dihydrolinalool
- Physical state: Liquid
- Storage condition of test material: In refrigerator protected from light
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
Not relevant

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
sewage, domestic, non-adapted
Details on inoculum:
- Source of inocculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Secondary effluent freshly obtained from a municipal sewage treatment plant: "Waterschap de Maaskant", 's Hertogenbosch, The Netherlands
- Pretreatment: Secondary effluent was filtered through a coarse filter paper, the first 200 ml was discarded.
- Storage conditions: The filtrate was kept aerated until inoculation
- Inoculation: 0.1 ml filtrate of secondary effluent per litre of final volume
Duration of test (contact time):
28 d
Initial test substance concentrationopen allclose all
Initial conc.:
1.031 mg/L
Based on:
test mat.
Initial conc.:
2.062 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: Mineral medium according to the testing guideline
- Test temperature: Recorded daily in a vessel in the same room
- pH: Recorded at the start of the test in all test bottles
- pH adjusted: no
- Continuous darkness: yes

TEST SYSTEM
Parallel groups of 250-300 ml BOD bottles with glass stoppers were prepared to allow duplicate measurements of oxygen consumption at the test intervals. The oxygen concentration was determined immediately at the start of the experiment (day 0), and at day 7, 14, 21 and 28 in duplicate.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Containing only inoculum
- Toxicity control: Containing test substance, reference substance and inoculum
- Positive control: Containing 2 mg/l reference substance

Reference substance
Reference substance:
acetic acid, sodium salt
Remarks:
Merck art. 6268, batch 049 TA933768

Results and discussion

Preliminary study:
Not applicable
Test performance:
The temperature varied between 19.5°C and 21.0°C. The pH recorded at the start of the test was 7.6 in all test bottles.
The positive control showed 75% biodegradation within 7 days. The oxygen depletion in the inoculum blank was 0.93 mg O2/l The oxygen depletion
in the toxicity control was always more than 75% of the sum of the oxygen depletion in the positive control and 1.031 mg/l Dihydrolinalool.
Therefore, Dihydrolinalool was assumed to be not inhibitory.
% Degradationopen allclose all
Parameter:
% degradation (O2 consumption)
Value:
10
Sampling time:
7 d
Remarks on result:
other: High test subst concentration (2 mg/l)
Parameter:
% degradation (O2 consumption)
Value:
64
Sampling time:
28 d
Remarks on result:
other: High test subst concentration (2 mg/l)
Parameter:
% degradation (O2 consumption)
Value:
32
Sampling time:
7 d
Remarks on result:
other: Low test subst. concentration (1 mg/l)
Parameter:
% degradation (O2 consumption)
Value:
63
Sampling time:
28 d
Remarks on result:
other: Low test subst. concentration (1 mg/l)
Details on results:
The relative biodegradation values calculated from the O2 measurements performed during the test period of 28 days revealed significant
degradation of Dihydrolinalool at both concentrations. After 7 days of incubation degradation was 32% at 1 mg/l Dihydrolinalool and 10% at 2 mg/l
Dihydrolinalool. After 14 days biodegradation had increased to levels of 59% and 54% respectively. Biodegradation tended to level-off at
approximately 65% in both test concentrations. For detailed results see the Table included in overall remarks.
Furthermore, the limit for ready biodegradability (i.e. 60% of degradation within 28 days, obtained within 10 days of biodegradation exceeding 10%) was met for the high concentration (2.062 mg/l) of Dihydrolinalool, as can be seen in the attached figure.

BOD5 / COD results

Results with reference substance:
Not relevant

Any other information on results incl. tables

Test medium

Concentration (mg/l)

Oxygen depletion (mg BOD/l) after x days

0

7

14

21

28

Positive control

2.052

0

75

72

76

72

Test substance low

1.031

0

32

59

59

63

Test substance high

2.062

0

10

54

65

64

 

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
Oxygen depletion in inoculum blank <1.5 mg O2/l, residual O2 concentration in test bottles >0.5 mg/l at all times, difference between duplicates <20% and control substance degraded >60% within 7 days
Interpretation of results:
readily biodegradable
Conclusions:
Dihydrolinalool was readily biodegradable under the conditions of the closed bottle test performed.
Executive summary:

The biodegradability of Dihydrolinalool was tested in a closed bottle test (OECD TG 301D). The validity criteria for the test were met. The relative biodegradation values calculated from the O2 measurements performed during the test period of 28 days revealed significant degradation of Dihydrolinalool at both concentrations. After 28 days of incubation degradation approximately 65% in both test concentrations. Furthermore, the limit for ready biodegradability (i.e. 60% of degradation within 28 days, obtained within 10 days of biodegradation exceeding 10%) was met for the high concentration (2.062 mg/l) of Dihydrolinalool.

In conclusion, Dihydrolinalool was readily biodegradable under the conditions of the closed bottle test performed.