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Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Remarks:
The study on a similar substance serves as data source for the endpoint study record "TARGET - Biodegradation in water: screening tests_Capa203" and the justification for read-across is provided there.
Adequacy of study:
key study
Study period:
Not reported
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
Study conducted to OECD 301B, GLP compliant
Justification for type of information:
Study serves as data source; read-across justification is found in corresponding Target record.
Reason / purpose for cross-reference:
read-across source
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
no
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
Secondary (biological) activated sludge was obtained from the RWZI Horstermeer in Nederhorst den Berg, The Netherlands on January 13, 1993. The RWZI Horstermeer was an activated sludge plant treating predominantly domestic waste water. The dry weight of this inoculum appeared to be 4.0 mg/ml.
Duration of test (contact time):
28 d
Initial conc.:
20 mg/L
Based on:
test mat.
Initial conc.:
10 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
CO2 evolution
Reference substance:
acetic acid, sodium salt
Key result
Parameter:
% degradation (TOC removal)
Value:
ca. 60
Sampling time:
7 d
Remarks on result:
other: initial conc. 10 mg/L
Parameter:
% degradation (TOC removal)
Value:
ca. 84
Sampling time:
28 d
Remarks on result:
other: initial conc. 10 mg/L
Parameter:
% degradation (TOC removal)
Value:
ca. 42
Sampling time:
7 d
Remarks on result:
other: initial conc. 20 mg/L
Parameter:
% degradation (TOC removal)
Value:
ca. 56
Sampling time:
28 d
Remarks on result:
other: initial conc. 20 mg/L

Table 1: Results of the biodegradation test with CAPA 203 and sodium acetate. The results are expressed as CO2 mg (cumulative) formed after 7, 14, 21, 28 and 29 days (n=2)

Concentration

CAPA 203

(mg/L)

Concentration

Sodium acetate

(mg/L)

mg CO2 produced

7 days

14 days

21 days

28 days

29 days

 

 

 

 

 

 

 

0

100

44.0

56.9

60.8

59.4

59.8

20

100

37.6

61.5

71.4

73.1

72.9

10

0

28.6

35.7

38.6

40.0

40.2

20

0

39.9

50.8

52.4

53.2

53.2

Table 2: Percentage degradation of 100 mg/L sodium acetate, 20 mg/L CAPA 203 in the presence of 100 mg/L sodium acetate and CAPA 203 at a concentration of 10 and 20 mg/L

 

% biodegradation

7 days

14 days

21 days

28 days

29 days

 

 

 

 

 

 

sodium acetate (100 mg/L)

44

57

61

60

60

 

 

 

 

 

 

CAPA 203 (20 mg/L) in

the presence of sodium

acetate (100 mg/L)

-7

5

11

14

14

 

 

 

 

 

 

CAPA 203 (10 mg/L)

60

75

81

84

84

 

 

 

 

 

 

CAPA 203 (20 mg/L)

42

53

55

56

56

 

 

 

 

 

 

Table 3: Results of the biodegradability test

Concentration

CAPA 203

(mg/L)

Concentration

Sodium acetate

(mg/L)

mg CO2 of absorbed in the period

0-7

days

7-14

days

14-21

days

21-28

days

28-29

days

 

 

 

 

 

 

 

0

 

15.3

8.6

4.9

1.3

1.1

0

 

15.8

10.7

8.2

7.4

1.1

average

 

15.6

9.7

6.6

4.4

1.1

 

 

 

 

 

 

 

 

100

80.3

22.1

10.2

3.1

1.9

 

100

38.8

23.0

10.8

2.8

1.1

 

average

59.6

22.6

10.5

3.0

1.5

 

 

 

 

 

 

 

20

100

53.2

33.6

16.5

6.1

0.9

 

 

 

 

 

 

 

10

 

43.4

18.5

11.1

9.5

1.4

10

 

44.9

15.0

7.9

2.1

1.1

average

 

44.2

16.8

9.5

5.8

1.3

 

 

 

 

 

 

 

20

 

74.8

19.6

3.7

1.9

1.1

20

 

36.2

21.6

12.7

8.5

1.1

average

 

55.5

20.6

8.2

5.2

1.1

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The test substance CAPA 203 was classified as readily biodegradable.
Executive summary:

A study was conducted to guideline OECD 301B using the substance CAPA 203. The reference compound (sodium acetate) degraded to 60% within 28 days. The total CO2-evolution in the inoculum blank at the end of the test was 37 mg, which was below the maximum acceptable amount according to the guideline (40 mg CO2L). The substance CAPA 203 was 60% degraded within 7 days when incubated at a concentration of 10 mg/L and 42% degraded when incubated at a concentration of 20 mg/L. On the basis of this result, CAPA 203 was classified as readily biodegradable.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
Not reported
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
Study conducted to OECD 301B, GLP compliant
Justification for type of information:
It is considered appropriate to address the ready biodegradability data requirement for 2-oxepanone, polymer with 1,6-hexanediol by applying read-across from available experimental study data on 2-oxepanone, polymer with 1,4-butanediol. The source and target substances are low molecular weight polyester diols terminated by primary hydroxyl groups and are structurally similar in that they both contain 6-hydroxyhexanoic acid repeating units. The linking unit is 1,4-butanediol in 2-oxepanone, polymer with 1,4-butanediol and 1,6-hexanediol in 2-oxepanone, polymer with 1,6-hexanediol. The diols differ by two carbons in the aliphatic chain and are therefore sufficiently structurally similar to support a read-across approach. The source and target substances share similar physico-chemical properties in that both are liquids at room temperature and have similar water solubility and log Pow values. The substances are therefore sufficiently similar in terms of basic physico-chemical properties to support a read-across approach. A read-across justification document is attached in section 13.
Reason / purpose for cross-reference:
read-across source
Key result
Parameter:
% degradation (TOC removal)
Value:
ca. 60
Sampling time:
7 d
Remarks on result:
other: initial conc. 10 mg/L
Parameter:
% degradation (TOC removal)
Value:
ca. 84
Sampling time:
28 d
Remarks on result:
other: initial conc. 10 mg/L
Parameter:
% degradation (TOC removal)
Value:
ca. 42
Sampling time:
7 d
Remarks on result:
other: initial conc. 20 mg/L
Parameter:
% degradation (TOC removal)
Value:
ca. 56
Sampling time:
28 d
Remarks on result:
other: initial conc. 20 mg/L

Table 1: Results of the biodegradation test with CAPA 203 and sodium acetate. The results are expressed asCO2mg (cumulative) formed after 7, 14, 21, 28 and 29 days (n=2)

Concentration

CAPA 203

(mg/L)

Concentration

Sodium acetate

(mg/L)

mg CO2 produced

7 days

14 days

21 days

28 days

29 days

 

 

 

 

 

 

 

0

100

44.0

56.9

60.8

59.4

59.8

20

100

37.6

61.5

71.4

73.1

72.9

10

0

28.6

35.7

38.6

40.0

40.2

20

0

39.9

50.8

52.4

53.2

53.2

Table 2: Percentage degradation of 100 mg/L sodium acetate, 20 mg/L CAPA 203 in the presence of 100 mg/L sodium acetate and CAPA 203 at a concentration of 10 and 20 mg/L

 

% biodegradation

7 days

14 days

21 days

28 days

29 days

 

 

 

 

 

 

sodium acetate (100 mg/L)

44

57

61

60

60

 

 

 

 

 

 

CAPA 203 (20 mg/L) in

the presence of sodium

acetate (100 mg/L)

-7

5

11

14

14

 

 

 

 

 

 

CAPA 203 (10 mg/L)

60

75

81

84

84

 

 

 

 

 

 

CAPA 203 (20 mg/L)

42

53

55

56

56

 

 

 

 

 

 

Table 3: Results of the biodegradability test

Concentration

CAPA 203

(mg/L)

Concentration

Sodium acetate

(mg/L)

mg CO2 of absorbed in the period

0-7

days

7-14

days

14-21

days

21-28

days

28-29

days

 

 

 

 

 

 

 

0

 

15.3

8.6

4.9

1.3

1.1

0

 

15.8

10.7

8.2

7.4

1.1

average

 

15.6

9.7

6.6

4.4

1.1

 

 

 

 

 

 

 

 

100

80.3

22.1

10.2

3.1

1.9

 

100

38.8

23.0

10.8

2.8

1.1

 

average

59.6

22.6

10.5

3.0

1.5

 

 

 

 

 

 

 

20

100

53.2

33.6

16.5

6.1

0.9

 

 

 

 

 

 

 

10

 

43.4

18.5

11.1

9.5

1.4

10

 

44.9

15.0

7.9

2.1

1.1

average

 

44.2

16.8

9.5

5.8

1.3

 

 

 

 

 

 

 

20

 

74.8

19.6

3.7

1.9

1.1

20

 

36.2

21.6

12.7

8.5

1.1

average

 

55.5

20.6

8.2

5.2

1.1

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The target substance 2-oxepanone, polymer with 1,6-hexanediol (Capa-2047A) is estimated to be readily biodegradable, based on read-across from a reliable study testing Capa-203 (2-oxepanone, polymer with 1,4-butanediol).
Executive summary:

A study was conducted to guideline OECD 301B using the substance Capa-203 (2-oxepanone, polymer with 1,4-butanediol). The reference compound (sodium acetate) degraded to 60% within 28 days. The total CO2-evolution in the inoculum blank at the end of the test was 37 mg, which was below the maximum acceptable amount according to the guideline (40 mg CO2L). The substance Capa-203 was 60% degraded within 7 days when incubated at a concentration of 10 mg/L and 42% degraded when incubated at a concentration of 20 mg/L. On the basis of this result, Capa-203 was classified as readily biodegradable.

The basic physico-chemical properties and chemical structural of the source substance Capa-203 and the target substance Capa-2047A (2-oxepanone, polymer with 1,6-hexanediol) are considered to be sufficiently similar to support a read-across approach. Therefore, the target substance CAPA 2047A is also concluded to be readily biodegradable.     

Description of key information

One key study is presented, which shows that the read-across substance 2-oxepanone, polymer with 1,4-butanediol is readily biodegradable. The target substance 2-oxepanone, polymer with 1,6-hexanediol is therefore concluded to be readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:
freshwater

Additional information

The basic physico-chemical properties and chemical structural of the source substance 2-oxepanone, polymer with 1,4-butanediol and the target substance 2-oxepanone, polymer with 1,6-hexanediol are considered to be sufficiently similar to support a read-across approach. The read-across substance 2-oxepanone, polymer with 1,4-butanediol has been found to be readily biodegradable with 60% degradation within 7 days when incubated at a concentration of 10 mg/L and 42% degradation when incubated at a concentration of 20 mg/L. On the basis of this result the target substance was classified as readily biodegradable.