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Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
1973
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Test method is comparable to the OECD 301D Closed Bottle Test. The test result is plausible and in line with the predictions of the US EPA Property Estimation Program on Biodegradability, Version 4.02 (http://www.epa.gov/opptintr/exposure/docs/episuite.htm): BioWin model 1 and 2 'Biodegrades fast' BioWin model 5 and 6 'Readily biodegradable'. However, neither puritiy of test substance nor amount and source of activated sludge or any results for reference substances are given. Moreover, it is not specified if ThOD or COD served as a reference for the calculation of % degradation from BOD.
Principles of method if other than guideline:
Method: other: Closed Bottle Test similar to OECD 301D
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
sewage, predominantly domestic, non-adapted
Duration of test (contact time):
>= 20 d
Initial conc.:
12 mg/L
Based on:
test mat.
Key result
Parameter:
other: based on BOD
Value:
63
Sampling time:
20 d
Details on results:
Degradation is related to BOD : 292 mg/l after 20 d
Kinetic of test substance (in %):
0 after 5 day(s)
0 after 10 day(s)
63 after 20 day(s)
Validity criteria fulfilled:
not specified
Interpretation of results:
readily biodegradable
Conclusions:
2-chlorobenzaldehyde was degraded within 20 days by 63%. The substance was readily biodegradable.
Executive summary:

Biodegradability of 2 -chlorobenzaldehyde was determined in a test similar to Closed Bottle OECD 301 D based on BOD. In a 20-day window 63 % of the substance was degraded, starting from an initial concentration of 12 mg/l of the test substance. Thus, 2-chlorobenzaldehyde is readily biodegradable in the test.

Endpoint:
biodegradation in water: inherent biodegradability
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
1984-04-10 - 1984-05-02
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Result plausible and in line with results from Bayer_1973-2005-01-20, Hoechst_1986-08-27, and Wellens_1990.002 . The test was performed according to Zahn-Wellens (OECD 302 B), results are documented in a data sheet (W84-181) and a reevaluation of the respective raw data from 1996. Effective biodegradation of the reference substance diethylene glycol confirms the validity of the test.
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test)
Deviations:
not specified
Principles of method if other than guideline:
The extensive reevaluation of older data from Hoechst (Report date 1996-07-23) is based on the raw data from Hoechst, 1984. The test was performed according to OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test).
GLP compliance:
no
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
Not applicable;
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, industrial (adaptation not specified)
Duration of test (contact time):
22 d
Initial conc.:
151 mg/L
Based on:
DOC
Initial conc.:
300 mg/L
Based on:
DOC
Parameter followed for biodegradation estimation:
DOC removal
Details on study design:
TEST CONDITIONS

Test temperature: room temperature

TEST SYSTEM

Two different concentrations of the test substance were used for the degradation test:
A) 151 mg/L DOC Chlorobenzaldehyde and 271 mg/L Diethylene glycol as reference substance;
B) 300 mg/L DOC Chlorobenzaldehyde and 271 mg/L Diethylene glycol as reference substance;

For each experiment a blank control with sludge only was measured in prallel and the DOC-values substracted from the measured values of the test sample. The difference between the start concentration (i.e. either 151 or 300 mg/L DOC ) and the initial measurement at 3h incubation time was taken as adsorption/elimination.
Further time points of DOC measurement for the blank control, the reference (Diethylene glycol) and the sample with test substance were (in days): 1, 3, 6, 8, 10, 13, 15, 17, 20, 22.



Reference substance:
diethylene glycol
Preliminary study:
None
Test performance:
Effective biodegradation of the reference substance diethylene glycol confirms the validity of the test.
Key result
Parameter:
% degradation (DOC removal)
Value:
> 95
Sampling time:
10 d
Remarks on result:
other: 151.0 mg/L DOC at start of experiment
Parameter:
% degradation (DOC removal)
Value:
> 80
Sampling time:
13 d
Remarks on result:
other: 151.0 mg/L DOC at start of experiment
Parameter:
% degradation (DOC removal)
Value:
> 90
Sampling time:
20 d
Remarks on result:
other: 300.0 mg/L DOC at start of experiment
Key result
Parameter:
% degradation (DOC removal)
Value:
> 95
Sampling time:
22 d
Remarks on result:
other: 300.0 mg/L DOC at start of experiment
Details on results:
For experiment A (test substance concentration 151.0 mg/L DOC) no adsorption was found (no reduction of DOC) after 3h incubation.
For experiment B (test substance concentration 300.0 mg/L DOC) 4% adsorption was found (4% reduction of DOC) after 3h incubation.
For the respective detailed kinetics of the test substance as well as the reference on experiments A and B see details in tables under "overall remarks"
Results with reference substance:
96,3% degradation in 13 days

A) Degradation of the test substance concentration in percent: Initial test substance concentration was 151.0 mg/L DOC. Initial reference substance concentration was 271 mg/L DOC

time of incubation:

reference substance
mg/l

reference substance
degradation

test substance
elimination

test substance
degradation

decisive time points

Elimination

Degradation

0.125 (= 3h)

270.00 

0.0%

0.0%

0.0%

3 h

0% Ads.

0%

1

277.00 

0.0%

0.0%

0.0%

 

 

 

3

253.00 

6.3%

0.0%

0.0%

 

 

 

6

147.00 

45.6%

75.5%

75.5%

6 d

> 70%

> 70%

8

51.00 

81.1%

93.4%

93.4%

8 d

> 90%

> 90%

10

6.00 

97.8%

100.7%

100.7%

10 d

> 95%

> 95%

13

10.00 

96.3%

84.1%

84.1%

13 d

> 80%

> 80%

15

 

 

 

 

 

 

 

17

 

 

 

 

 

 

 

20

 

 

 

 

 

 

 

B) Degradation of the test substance concentration in percent: Initial test substance concentration 300.0 mg/L DOC; Initial reference substance concentration 271 mg/L DOC;

time of incubation:

reference substance
mg/l

reference substance
degradation

test substance
elimination

test substance
degradation

decisive time points

Elimination

Degradation

0.125 (= 3h)

270.00 

0.0%

4.0%

0.0%

3 h

4% Ads.

0%

1

277.00  

0.0%

3.7%

0.0%

 

 

 

3

253.00 

6.3%

3.3%

0.0%

 

 

 

6

147.00 

54.6%

8.3%

4.5%

 

 

 

8

51.00 

81.1%

28.7%

25.7%

8 d

20% - 50%

20% - 50%

10

6.00 

97.8%

45.3%

43.1%

 

 

 

13

10.00 

96.3%

59.0%

57.3%

13 d

50% - 70%

50% - 70%

15

 

 

72.7%

71.5%

 

 

 

17

 

 

85.0%

84.4%

17 d

> 80%

> 80%

20

 

 

91.7%

91.3%

20 d

> 90%

> 90%

22

 

 

100.0%

100.0%

22 d

> 95%

> 95%

Validity criteria fulfilled:
yes
Interpretation of results:
inherently biodegradable
Conclusions:
2-chlorobenzaldehyde was degraded
in experiment A (151.0 mg/L DOC initial concentration) within 10 days of incubation by 95% and
in experiment B (300.0 mg/L DOC initial concentration) within a 10 day window by about 75% at day 16.
Elimination by other than biotic procecces was not observed (experiment A) or with 4% low (experiment B).
The substance therefore is inherently biodegradable and moreover fulfills the 10-day window as a prerequisite for ready biodegradability.
Executive summary:

Biodegradability of 2-chlorobenzaldehyde was tested according to OECD 302 B (Zahn-Wellens) for the initial concentrations 151 mg/L and 300 mg/L DOC, respectively. As reference substance diethylene glycol was used as a positive control. For each experiment, a blank with sludge only was measured at each time point of DOC-measurements and subtracted from the DOC-value of the test-sample. The first measurement at 3h after the start of the experiment served (after substraction of the blank value and by comparison with the initital concentration) as a measure of elimination other than degradation (adsorption). Adsorption proved to be absent (151 mg/L initial concentration) or low (300 mg/L initial concentration). DOC-values for blank, test item and reference substance were further taken at time points 1, 3, 6, 8, 10, 13, 15, 17, 20 and 22 days. 2-chlorobenzaldehyde was degraded

in experiment A (151.0 mg/L DOC initial concentration) within 10 days of incubation by 95% and

in experiment B (300.0 mg/L DOC initial concentration) within a 10 day window by about 75% at day 16 and by more than 95% at the end of the experiment (day 22). The substance therefore is inherently biodegradable.

Endpoint:
biodegradation in water: inherent biodegradability
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
1990
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Sound study according to OECD-guideline 302 B. However, pre GLP, no information on purity of substance, certain experimental details missing.
Qualifier:
according to guideline
Guideline:
OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test)
Deviations:
not specified
Guideline:
other: DIN-Norm 38412
Deviations:
not specified
GLP compliance:
not specified
Oxygen conditions:
not specified
Inoculum or test system:
activated sludge, industrial, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: Waste water treatment plant of Hoechst-AG
- Concentration of sludge: 1.1 +-0.1 g/l dry matter
Duration of test (contact time):
13 d
Initial conc.:
>= 50 - <= 400 mg/L
Based on:
DOC
Initial conc.:
>= 200 - <= 1 000 mg/L
Based on:
COD
Parameter followed for biodegradation estimation:
DOC removal
Parameter followed for biodegradation estimation:
other: COD
Details on study design:
TEST CONDITIONS
- Additional substrate: None
SAMPLING:
The amount of test substance eliminated after 3 hours was taken as physically absorbed and not degraded.

Reference substance:
aniline
Key result
Parameter:
other: DOC-removal or COD
Value:
100
Sampling time:
13 d
Details on results:
2-Chlorobenzaldehyde:
- Depletion of test substance after three hours (physical absorption): 0 %
- Acclimatization period: 10 days
- Logarithmic phase: 3 days with 100% degradation
- Total time: 13 days with 100% degradation;

Results with reference substance:
Aniline, as part of a large list of investigated substances:
- Depletion of test substance after three hours (physical absorption): 12 %
- Acclimatization period: 0 days
- Logarithmic phase: 6 days with 90% degradation
- Total time: 9 days with 100% degradation;
Validity criteria fulfilled:
yes
Remarks:
Procedural control (Aniline): removal by 100% within 6d
Interpretation of results:
inherently biodegradable
Conclusions:
Under the condition of this test 2-chlorobenzaldehyde is degraded within 13 days by 100%. The substance 2-chlorobenzaldehyde is inherently biodegradable.
Executive summary:

Inherent biodegradability of 2 -chlorobenzaldehyde was determined according to OECD-Guideline 302 B. An initial substance concentration between 50 and 400 mg/L DOC was used in the test. For degradation in mineral medium activated sludge (~ 1 g/L) of the waste water treatment plant of Hoechst AG was used. From regular measurements of the COD or DOC-values degradation curves were derived, specifying an initial acclimatization period (lag phase) with low or very limited degradation, a log-phase with enhanced degradation and finally a plateau. The derived degradation determined after 3 hours is taken as physical elimination of the test substance.

For 2 -chlorobenzaldehyde there was no physical elimination. After an acclimatisation period of 10 days, a degradation of 100% within the following 3 days had been found. Thus, the substance 2 -chlorobenzaldehyde is inherently biodegradable according to this test.

Description of key information

Weigth-of-evidence from two reliable studies on inherent biodegradation and one study on ready biodegradation consistently shows that 2-chlorobenzaldehyde is (at least) inherently biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable

Additional information

A reliable study (Hoechst_1984, reliability 2) on inherent biodegradation, which was performed according to OECD-Guideline 302 B (Zahn-Wellens), shows 2-chlorobenzaldhyde to be inherently biodegradable: 2-chlorobenzaldehyde was degraded in experiment A (151.0 mg/L DOC initial concentration) within 10 days of incubation by 95% and in experiment B (300.0 mg/L DOC initial concentration) within a 10 day window by about 75% at day 16 and by more than 95% at the end of the experiment (day 22). The study therefore shows the inherent, ultimate biodegradability of the test substance.

In another reliable study (Wellens_1990, reliability 2) performed also according to OECD-Guideline 302 B (Zahn-Wellens), within 13 days 100% of 2 -chlorobenzaldehyde was degraded and degradation proceeded in a 3 - day window corroborating the conclusion from the first study.

A insufficiently documented (therefore reliability category 3) study on readybiodegradability performed similar to Closed Bottle (OECD 301 D) with nonadaptedinoculum resulted in a degradation of 63 % (BOD) in a 10 day window within 20 days (Bayer_1973), fulfilling the requirements for ready biodegradability.

In a weight-of-evidence evaluation of these three studies it is concluded that 2 -chlorobenzaldehyde should be regarded as (at least) inherently biodegradable.

This conclusion is supported by an additional, less documented study on inherent biodegradation (Hoechst_1986, RL3), which shows inherent biodegradability in a test equivalent to OECD-Guideline 302 B. A study performed according to OECD-Guideline 301 C (MITI I), reported in a secondary source, showed only primary biotransformation to 2 - chlorobenzoic acid and 2 -chlorobenzyl alcohol. As this study is lacking important information, e.g. a reference substance demonstrating the functionality of the test conditions, its reliability is doubtful. In conclusion, the unequivocal results of the four other studies are not put into question by the MITI-study.