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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:
2008-11-10 - 2009-01-28
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: The GLP study was conducted according to an internationally accepted guideline. All study parameters are based on the specific guideline.
Qualifier:
according to
Guideline:
OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test)
Deviations:
yes
Remarks:
The number of replicates of the treatment groups reference item and toxicity control were reduced from 2 to 1.
Qualifier:
according to
Guideline:
OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test)
Deviations:
yes
Remarks:
The storing of the samples at < -18 °C was prolonged from 14 to 28 days.
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)
Details on inoculum:
As microbial source (inoculum) for the test a fresh sample from the secondary effluent of a sewage treatment plant was used (sampling date: 13.11.2008). Before test start, the collected sample was decanted and filtered through a coarse filter paper.
About 1 hour after sampling at the sewage treatment plant, the inoculum was used in the test (< 0.5 mL/L mineral medium).
Duration of test (contact time):
28 d
Initial conc.:
64 mg/L
Based on:
DOC
Parameter followed for biodegradation estimation:
DOC removal
Details on study design:
The test item dissolved in mineral medium was inoculated with micro-organisms (inoculum) from a mixed population and kept in conical glass flasks (1 L glass flask) at diffuse light and constant temperature.
Additionally a control group (mineral medium with inoculum), a reference item group (mineral medium with inoculum + reference item) and a toxicity control group (mineral medium with inoculum + test item + reference item) were run in parallel.
The degradation of the test item or reference item was followed by DOC analysis at frequent intervals over a 28-day period.
The degree of biodegradation was calculated by expressing the concentration of DOC removed as a percentage of the concentration initially presented.
Reference substance:
acetic acid, sodium salt
Parameter:
% degradation (DOC removal)
Value:
4.9
Sampling time:
5 d
Parameter:
% degradation (DOC removal)
Value:
30.5
Sampling time:
11 d
Parameter:
% degradation (DOC removal)
Value:
30.5
Sampling time:
20 d
Parameter:
% degradation (DOC removal)
Value:
32.5
Sampling time:
25 d
Parameter:
% degradation (DOC removal)
Value:
32
Sampling time:
28 d

Results with test item:

Sampling day

 

Measured Dissolved Organic Carbon (POC)

[mg/L mineral medium]

 

Biodegradationrate

[%]

 

Control (blank)

Test item(64mg/L)

 

 

Replicate

 

Replicate

 

 

 

I

II

mean

I

II

mean

 

0

1.701

2.297

1.999

35.36

37.18

36.27

0

4

0.807

1.648

1.2275

35.72

36.22

35.97

-1.38

5

1.049

1.014

1.0315

33.53

33.74

33.64

4.87

7

1.163

0.800

0.9815

26.95

26.07

26.51

25.51

8

1.210

1.374

1.292

26.34

25.57

25.96

28.04

11

1.105

1.141

1.123

24.97

24.93

24.95

30.47

13

0.803

1.238

1.0205

24.58

22.76

23.67

33.91

15

1.122

1.317

1.2195

25.24

23.91

24.58

31.85

18

0.934

0.957

0.9455

23.77

23.03

23.40

34.48

20

1.312

1.773

1.5425

26.12

24.61

25.365

30.49

22

2.069

1.866

1.9675

25.85

25.13

25.49

31.36

25

1.211

1.411

1.311

24.93

23.97

24.45

32.48

27

1.703

1.653

1.678

25.04

25.12

25.08

31.71

28

1.383

1.862

1.6225

24.88

24.96

24.92

32.02

Results with reference substance:

Sampling day

 

Measured Dissolved Organic Carbon (DOC)

[mg/L mineral medium]

Biodegradationrate

t%]

 

 

Control (blank)

 

Reference item

 

 

Replicate

 

(100mg/L)

 

 

I

II

mean

 

 

0

1.701

2.297

1.999

30.57

0

4

0.807

1.648

1.2275

20.94

31.50

5

1.049

1.014

1.0315

4.52

85.21

7

1.163

0.800

0.9815

3.52

88.49

8

1.210

1.374

1.292

3.38

88.94

11

1.105

1.141

1.123

1.96

93.59

13

0.803

1.238

1.0205

2.35

92.31

15

1.122

1.317

1.2195

2.45

91.99

18

0.934

0.957

0.9455

2.63

91.40

20

1.312

1.773

1.5425

5.08

83.38

22

2.069

1.866

1.9675

4.73

84.53

25

1.211

1.411

1.311

2.51

88.81

27

1.703

1.653

1.678

3.42

88.81

28

1.383

1.862

1.6225

2.88

90.58

Validity criteria fulfilled:
yes
Interpretation of results:
other: not readily biodegradable
Conclusions:
The biodegradation of N-[3(5)-Methyl-1H-pyrazol-1-yl-methyl]acetamide was determined according to OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test). The biodegradation rate of the test item at a concentration of 64 mg/L mineral medium was calculated to be about 32 % after the 28-day test period. Since the degree of biodegradation of the test item did not reach 70 % (based on DOC) within a 10-day window (beginning at a degradation rate of 10 %), the test item cannot be classified as readily biodegradable. The biodegradation rate of the toxicity control was calculated to be about 64 % at the end of the test period (day 28). Therefore, the test item cannot be assumed to be inhibitory (required: 35 % biodegradation).
Executive summary:

The biodegradation of N-[3(5)-Methyl-1H-pyrazol-1-yl-methyl]acetamide was determined according to OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test). The biodegradation rate of the test item at a concentration of 64 mg/L mineral medium was calculated to be about 32 % after the 28-day test period. Since the degree of biodegradation of the test item did not reach 70 % (based on DOC) within a 10-day window (beginning at a degradation rate of 10 %), the test item cannot be classified as readily biodegradable. The biodegradation rate of the toxicity control was calculated to be about 64 % at the end of the test period (day 28). Therefore, the test item cannot be assumed to be inhibitory (required: 35 % biodegradation).

Description of key information

The biodegradation of N-[3(5)-Methyl-1H-pyrazol-1-yl-methyl]acetamide was determined according to OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test). The biodegradation rate of the test item at a concentration of 64 mg/L mineral medium was calculated to be about 32 % after the 28-day test period. Since the degree of biodegradation of the test item did not reach 70 % (based on DOC) within a 10-day window (beginning at a degradation rate of 10 %), the test item cannot be classified as readily biodegradable. The biodegradation rate of the toxicity control was calculated to be about 64 % at the end of the test period (day 28). Therefore, the test item cannot be assumed to be inhibitory (required: 35 % biodegradation).

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable, not fulfilling specific criteria

Additional information

N-[3(5)-Methyl-1H-pyrazol-1-yl-methyl]acetamide is considered as not readily biodegradable.