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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:
20 Sep - 04 Oct 1982
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study without detailed documentation
Reason / purpose:
reference to other study
Related information:
Composition 1
Reference:
Composition 0
Qualifier:
according to
Guideline:
other: “Biodegradation test of chemical substance by microorganisms” (Kanpogyo No. 5, Yakuhatsu No. 615 and 49 Kikyoku No. 392)
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))
Deviations:
yes
Remarks:
Test duration only 14 d.
GLP compliance:
no
Test material information:
Composition 1
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): The activated sludge was purchased every three months from Chemicals Inspection & Testing Institute, Japan and cultivated in the laboratory.
- Concentration of suspended solids: 4628 ppm
Duration of test (contact time):
14 d
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Parameter followed for biodegradation estimation:
test mat. analysis
Details on study design:
TEST SYSTEM
- Number of culture flasks/concentration: 2
- Measuring equipment: Automatically measuring apparatus of oxygen consumption (Coulometer, Ohkura Electric Co., Ltd.)

SAMPLING
- Sampling frequency: O2 consumption was measured after 7 and 14 d
- Sampling method: Measured automatically

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, one bottle
- Toxicity control: no, but see cross-reference
- Other: reference substance: yes, one bottle
Reference substance:
aniline
Parameter:
% degradation (O2 consumption)
Value:
0
Sampling time:
14 d
Remarks on result:
other: Reported as: -0.6%
Parameter:
% degradation (test mat. analysis)
Value:
0
Sampling time:
14 d
Remarks on result:
other: Reported as: -0.5%
Details on results:
The study was not performed for 28 d since it was already visible after 14 d that the substance will not be degraded by microorganisms.
Results with reference substance:
The reference substance was degraded to 62.3% after 7 d and 69.1% after 14 d.

Table 1: Results of the oxygen consumption analysis

Test solutions

Amount

of sample

(mg)

Theoretical oxygen demand (mg)

7 days

14 days

Oxygen consumption (mg)

Degradation rate

(%)*

Oxygen consumption (mg)

Degradation rate

(%)

1) Aniline

+ activated sludge

30.0

90.3

59.9

62.3

67.2

69.1

2) Activated sludge

0

3.6

4.8

3) Test item

+ activated sludge

30.0

80.4

3.6

0

4.8

0

4) Test item

+ activated sludge

30.3

81.2

3.0

-0.7

3.9

-1.1

5) Test item

+ water

30.2

0.3

0.6

6) Test item

+ water

30.0

0

0.3

 

Average degradation rate:

-0.4 (r = 0.7)

Average degradation rate:

-0.6 (r = 1.1)

 

Table 2: Biodegradation test: Results of the residual analysis by GC

Test solutions

Amount of the test substance added

 A (mg)

Amount injected

(mL)

Sensitivity

(10-2A.U.)

Peak area

(Indicated value of integrator)

Concentration of the test substance

B (mg/mL)

Total volume

C (mL)

Recovery rate

D (%)

Residual amount (mg)

E =

Residual rate (%)

F=´100

Degra-dation rate

G (%)

Average degra-

dation rate (%)

Test item - Standard solution

4.0

16

376105

600

2) Activated sludge

0

4.0

16

0

0

50

3) Test item

+ activated sludge

30.0

4.0

16

375271

599

50

97.2

30.8

102.7

-2.3

-0.5

(r = 3.7)

4) Test item

+ activated sludge

30.3

4.0

16

365709

583

50

97.2

30.0

99.0

1.4

5) Test item

+ water

30.2

4.0

16

371786

593

50

96.5

30.7

101.7

100.4

6) Test item

+ water

30.0

4.0

16

359400

573

50

96.5

29.7

99.0

Interpretation of results:
under test conditions no biodegradation observed

Description of key information

Not expected to be readily biodegradable: 0% after 14 d (O2 consumption/test material analysis, similar to OECD 301C)

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed
Type of water:
freshwater

Additional information

One experimental study is available investigating the biodegradation of 2-(1,1-dimethylethyl)-6-[[3-(1,1-dimethylethyl)-2-hydroxy-5-methylphenyl]methyl]-4-methylphenyl acrylate (CAS 61167-58-6). The study was performed according “Biodegradation test of chemical substance by microorganisms” (Kanpogyo No. 5, Yakuhatsu No. 615 and 49 Kikyoku No. 392), which is equivalent or similar to the OECD Guideline 301C. In contrast to today’s standard methods the test duration was only 14 d. Activated sludge was exposed to 100 mg/L of the test item and the O2 consumption as well as specific test material analysis were used to assess biodegradation over time. After 14 d a biodegradation of 0% based on O2 consumption and test material analysis was recorded. Even though the test duration was only 14 d this result indicates strong evidence that the substance is not readily biodegradable according to the OECD criteria. Inhibition of activated sludge microorganisms is not likely since the available study according to OECD 209 did indicate low inhibition of the respiration of activated sludge microorganisms up to a concentration of 1000 mg/L.