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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
Study period:
2002-02-15 to 2002-05-23
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)
Version / remarks:
1992
Deviations:
no
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Version / remarks:
1992
Deviations:
no
Qualifier:
according to
Guideline:
other: ISO/DIS 14593 (1997)
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
- Source of activated sludge: Marl-Ost municipal sewage treatment plant
- Storage conditions: Under aeration in the dark
- Storage length: Six days
- Preparation of inoculum for exposure: Aeration of inoculum in mineral medium for six days.
- Concentration of sludge: Dry matter content in inoculum was 3.05 g/L. Content of colony forming units (CFU) was 370000 CFU/mL
- Initial cell/biomass concentration: 5.2 mg/L
- Bidestilled water was used for the preparation of the mineral medium
Duration of test (contact time):
28 d
Initial conc.:
49.2 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
inorg. C analysis
Details on study design:
TEST CONDITIONS
The test was carried out in accordance with Directive 92/69/EEC C.4-C, OECD 301 B and ISO/DIS 14593.
- Composition of medium: carried out to guideline, with bidest. water
- Test temperature: 20.6-22.7°C (mean 21.8°C)
- pH: Measured at the end of the test
Blank pH7.5
Sodium benzoate pH7.0
Trimethylorthoformate pH6.9
- Aeration of dilution water: sealed vessels
- Suspended solids concentration: Initial 5.2 mg/L
- Continuous darkness: yes
- Test vessles placed on an orbital shaker and shake with 180 rpm

TEST SYSTEM
- Culturing apparatus: ca 210 ml gas-tight glass vessels sealed with butyl rubber septa and aluminium crimp seals.
The test material was dosed to a defined volume of liquid mineral medium which was already inoculated with an activated-sludge inoculum.
- Number of culture flasks/concentration:
20 vessels without test item with inoculum
20 vessels containing reference item and inoculum
20 vessels containing test item and inoculum
- Measuring equipment: Evolved CO2 measured via TIC analysis in a Shimadzu carbon analyser


SAMPLING
- Sampling frequency: sampling after 0, 3, 7, 10, 14, 21 and 28 days
- Sampling method: Sacrificial vessels. TIC analysis of the bound CO2


CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
No other controls

STATISTICAL METHODS:
Calculations performed with Excel
Reference substance:
benzoic acid, sodium salt
Preliminary study:
No preliminary test was performed
Test performance:
All validity criteria were fulfilled
Parameter:
% degradation (inorg. C analysis)
Value:
88
Sampling time:
10 d
Details on results:
Since the degradation of Trimethylorthoformate was > 60 % in the course of 10 days after the lag phase (10% biodegradation), Trimethylorthoformate is considered to be „readily biodegradable".

Trimethylorthoformat was completely mineralised (108%) over the 28 day test period.
Results with reference substance:
The reference item sodium benzoate was completely mineralised (97 % degradation) over the 28 day test period. It can be concluded that the inoculum used had a sufficient biological activity.

 

Concentration: 49.2 mg/L => 22.3 mg C/L

                        2.9 mg C/vessel

  

Test duration (days)

TIC

(mg/L)

TIC

(mg/vessel)

Degradation %

Degradation %

 

test item

mean of the blank value

test item

mean of the blank value

 

mean

0

1.86

1.98

0.24

0.26

-0.69

-1

0

1.74

1.98

0.23

0.26

-1.03

3

9.86

1.98

1.28

0.26

35.17

36

 

3

10.04

1.98

1.31

0.26

36.21

7

17.07

2.00

2.22

0.26

67.59

68

 

7

17.40

2.00

2.26

0.26

68.97

10

22.62

2.02

2.94

0.26

92.41

88

 

10

20.64

2.02

2.88

0.26

83.45

14

23.76

2.20

3.09

0.29

96.55

93

 

14

22.29

2.20

2.90

0.29

90.00

21

24.87

1.96

3.23

0.25

102.76

101

 

21

23.82

1.96

3.10

0.25

98.28

28

27.33

2.22

3.55

0.29

112.41

108

 

28

25.23

2.22

3.28

0.29

103.10

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
Trimethylorthoformate is considered to be „readily biodegradable”.
Executive summary:

The ready biodegradability of Trimethylorthoformate (CAS 149-73-5) was tested according to OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test, 1992) or EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test, 1992). Activated sludge from the Marl-Ost municipal sewage treatment plant was used in the test. The test material (Trimethylorthoformate, 99.5% purity) was dosed at 49.2 mg/L .

Since the degradation of of the test substance was > 60 % in the course of 10 days after the lag phase (10% biodegradation), Trimethylorthoformate is considered to be „readily biodegradable”.

The reference item sodium benzoate was completely mineralised (97 % degradation) over the 28 day test period. It can be concluded that the inoculum used had a sufficient biological activity.

Description of key information

Readily biodegradable, OECD 301B

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

The guideline study of Ernst & Diefenbach (2002), which is considered to be reliable and accurate concludes that trimethylorthoformate is readily biodegradable. The study is considered reliable for classification and for use in risk assessments.