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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:
21 Feb - 21 Mar 2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013
Report Date:
2013

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
other: Testing Methods for New Chemical Substances
Version / remarks:
N° 0331-7, Pharmaceutical and Food Safety Bureau, Ministry of Health, Labour and Welfare; March 29, 2011, N° 5, Manufacturing Industries Bureau, Ministry of Economy, Trade and Industry; n° 110331009, Environmental Policy Bureau, Ministry of the Environment, Japan
Deviations:
not specified
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))
Deviations:
no
GLP compliance:
yes
Remarks:
according to Japanese "Standard Concerning Testing Facility Relating to New Chemical Substances", which can be considered equivalent to European standards.

Test material

Reference
Name:
Unnamed
Type:
Constituent
Specific details on test material used for the study:
- water solubility: > 50 mg/mL
- stability: stable for a year at room temperature
- storage conditions: at room temperature

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge: standard activated sludge (4223 mg/L) purchased from Chemicals Evaluation and Research Institute, Japan, on 11 Jan 2013
- Method of cultivation: 25 ± 2 °C, at least 5 mg/L dissolved oxygen, pH 7.0 ± 1.0
- Preparation of inoculum for exposure: not specified
- Concentration of sludge: 30 mg/L
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimationopen allclose all
Parameter followed for biodegradation estimation:
O2 consumption
Remarks:
measured continuously
Parameter followed for biodegradation estimation:
DOC removal
Parameter followed for biodegradation estimation:
test mat. analysis
Parameter followed for biodegradation estimation:
other: analysis of predicted degradation products
Details on study design:
TEST CONDITIONS
- Test temperature: 25 °C
- pH: 7.47 - 8.15
- pH adjusted: no
- Continuous darkness: not specified

TEST SYSTEM
- Culturing apparatus: not specified
- Number of culture flasks/concentration: 3
- Method used to create aerobic conditions: not specified
- Measuring equipment: Coulometer: Type OM-2001A, Ohkura Electric Co., Ltd.; Data sampler: DS-3, Asahi Techneion Co., Ltd.
- Test performed in closed vessels due to significant volatility of test substance: not specified, no significant volatility
- Test performed in open system: not specified

SAMPLING
- Sampling frequency: Oxygen consumption: continuous; Temperature, Solubility, Color and Sludge proliferation: daily; pH: at the end of exposure; Total dissolved organic carbon: at the end of exposure

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, one bottle
- Abiotic sterile control: yes, one bottle
- Reference substance: yes, one bottle
- Toxicity control: no

STATISTICAL METHODS:
- least square method: calculation of regression equation and regression coefficient for calibration curves for LC analysis
- mean values were calculated by the arithmetic mean
Reference substance
Reference substance:
aniline

Results and discussion

% Degradationopen allclose all
Key result
Parameter:
% degradation (O2 consumption)
Value:
0
Sampling time:
28 d
Parameter:
% degradation (test mat. analysis)
Value:
24
Sampling time:
28 d

BOD5 / COD results

Results with reference substance:
The degradation rate of the activity control substance aniline was higher than 40 % after 7 d exposure and higher than 65 % after 14 d exposure.

Any other information on results incl. tables

Table 1: Average degradation rate from BOD and from direct determination (LC analysis) of the test substance and main degradation substance.

 

 

 

Test solutions

Degradation rate (%)

Average degradation rate

Degradation rate

from BOD

3

Test suspension

0

 

0

4

Test suspension

1

5

Test suspension

- 1

Degradation rate

of the test substance

from direct

determination

( LC )

3

Test suspension

24

 

24

4

Test suspension

25

5

Test suspension

24

Degradation rate

of the main impurity of the test substance

from direct

determination

( LC )

3

Test suspension

0*11

 

0*11

 

4

Test suspension

0*11

5

Test suspension

0*11

 *11 From results of LC analysis of the main impurity of the test substance, its amount in test solutions after the exposure was larger than that added at the beginning. The main impurity of the test substance was estimated to be produced by the transformation of the test substance. Therefore, the amount of the main impurity at the beginning was assumed to fully remain during the exposure time (residual amount = amount added at the beginning), the degradation rate from LC analysis of the main impurity was calculated by using this assumed residual amount.

Table 2. Residual rates (%), production rates (%) and material balance of test substance, main impurity and main degradation products of the test substance.

 

 

Test solutions

Residual rate (%)

Production rate (%)

Test substance

 

Av.

Main impurity

 

Av.

Main impurity

 

Av.

degradation product 1

 

Av.

degradation product 2

 

Av.

3

Test suspension

73

 

73

100

 

100

8

 

0

 

0

0

4

Test suspension

73

100

8

0

0

5

Test suspension

74

100

8

0

0

6

Abiotic control

97

100

 

0

1

 

Test solutions

Production rate (%)

Material balance – 1 (%)

Material balance – 2 (%)

 

 

Degr. product 3

 

Av.

Degr. product 4

Av.

Degr. product 5

 

Av.

 

 

Av.

 

 

Av.

3

Test suspension

2

 

2

3

 

3

2

 

 2

86

 

86

94

 

92

4

Test suspension

2

3

2

85

90

5

Test suspension

2

3

2

86

93

6

Abiotic control

0

0

0

98

-

Note:

: Channel number of detection unit of coulometer

Production rate: (Production amount of each degradation product) / (Its theoretical [maximum] production amount by the degradation of test substance amount added at the beginning) x 100

Material balance-1: (The summation of residual amount [test substance and main impurity] and production amount*14[main impurity, degradation product 1, degradation product 2, degradation product 3, degradation product 4, and degradation product 5]) / (Test substance [test substance and main impurity] amount added at the beginning) x 100

Material balance-2: (The summation of the above residual and production*14amount and that of mineralized

degradation product 2 equivalent to DOC degradation rate of 5%) / (Test substance amount added at the beginning) x 100

*12 Theoretical [maximum] production amount of degradation products 1 and 2 was calculated on the assumption that they were derived from the hydrolysis of only the test substance, although they were considered to be produced from both the test substance andthe impurity of the test subtance.

*13 Since the degradation products 3, 4 and 5 were difficult to obtain as the analytical standards, the test substance was used as the analytical standard for quantitative analysis of these products on the assumption that each weight adsorption coefficient should be equal to that of the test substance.

*14 Because the production of the degradation product 1 and 2 by hydrolysis results in the addition of water molecule, the material balance will be overestimated by using the values (not corrected) of production amount of degradation products 1 and 2. Therefore, in order to avoid the overestimation due to the addition by water molecule, the material balance was evaluated with the correction taking it into account.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed