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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:
key study
Study period:
from 2008-10-20 to 2008-11-24
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Well documented guideline study.
Justification for type of information:
The justification for read across is provided as an attachment in IUCLID Section 13.
Reason / purpose:
read-across: supporting information
Qualifier:
according to
Guideline:
other: OECD 306: Biodegradability in seawater; closed bottle test.
Deviations:
yes
Remarks:
Ammonium chloride was omitted from the medium to prevent oxygen consumption due to nitrification and the oxygen consumption was measured at day 0, 7, 14 and 28 instead of day 5, 15 and 28
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material:
No test surrogate or analogue material
Oxygen conditions:
aerobic
Inoculum or test system:
natural water
Details on inoculum:
Seawater was collected from coastal water near the Oosterscheldedam (Banjaard, The Netherlands) at high tide (20-10-2008). The seawater was sampled approximately 10 cm below the water surface. The temperature of the water was 14.3°C. The seawater was aged to reduce the concentration of biodegradable compounds present in the seawater. To this end, the seawater was aerated for 7 days at room temperature in diffused light.
Duration of test (contact time):
28 d
Initial conc.:
1 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: Natural sea water + added nutrients:
KH2PO4 8.5 mg/L
K2HPO4 21.75 mg/L
Na2PO4 . 2H20 33.3 mg/L
MgSO4.7H20 22.5 mg/L
CaCl2 27.5 mg/L
FeCl3.6H2O 0.25 mg/L
Ammonium was omitted from the medium to prevent nitrification.
- Solubilising agent (type and concentration if used): silicone oil AR 20 (1 mL/L test medium)
- Test temperature: 18 +/- 2°C
- pH: 7.6
- pH adjusted: no
- Continuous darkness: yes


TEST SYSTEM
- Culturing apparatus: 0.30 L BOD bottles with glass stoppers
- Number of culture flasks/concentration:
10 bottles containing seawater and silicone oil
10 bottles containig the test substance (1.0 mg/L) in silicone oil and seawater
10 bottles containing sodium acetate (6.7 mg/L) and seawater
10 bottles containing only seawater
- Measuring equipment: see above §"details on analytical methods"
- Test performed in closed vessels due to significant volatility of test substance: yes



SAMPLING
- Sampling frequency: every week (7, 14, 21 and 28 days)
- Sampling method: two duplicate bottles of all series were withdrawn for analyses of the dissolved oxygen concentration at each sampling time
Reference substance:
acetic acid, sodium salt
Remarks:
6.7 mg/L
Preliminary study:
No preliminary study
Test performance:
The validity of the test is demonstrated by an endogenous respiration of 1.0 mg/L at day 28. The blank respiration therefore does not exceed 30% of the oxygen in the test bottles. Sodium acetate was degraded 85% of its ThOD after 28 days. The validity of the test is also shown by oxygen concentrations >0.5 mg/L in all bottles during the test period.
Parameter:
% degradation (O2 consumption)
Value:
74
Sampling time:
28 d
Details on results:
See § "Overall remarks" for detailed results
Results with reference substance:
Biodegradation of the reference substance was 85% at day 28 (see § "Overall remarks" for detailed results).

Table 1. Dissolved oxygen concentrations (mg/L) in the closed bottles.

 

Time (days)

Oxygen concentration (mg/L)

Oco

Ot

Oc

Oa

0

7.1

7.1

7.1

7.1

7.1

7.1

7.1

7.1

Mean (M)

7.1

7.1

7.1

7.1

7

6.9

5.2

6.8

2.7

6.7

4.8

6.9

2.6

Mean (M)

6.8

5.0

6.9

2.7

14

6.5

4.2

6.5

2.0

6.4

4.3

6.4

2.0

Mean (M)

6.5

4.3

6.5

2.0

21

6.1

3.9

6.0

1.5

6.1

3.8

6.1

1.4

Mean (M)

6.1

3.9

6.1

1.5

28

6.0

3.5

6.1

1.5

6.1

3.5

6.1

1.4

Mean (M)

6.1

3.5

6.1

1.5

Oco =    Seawater (inoculum) with mineral nutrient solution, with 0.3 mL of silicone oil but without test material.

Ot  =   Seawater (inoculum) with mineral nutrient solution with test material in silicone oil (1.0 mg/L).

Oc  =   Seawater (inoculum) with mineral nutrient solution but without test material and reference substance.

Oa =   Seawater (inoculum) with mineral nutrient solution with sodium acetate (6.7 mg/L).

 

 

Table 2. Oxygen consumption (mg/L) and the percentages biodegradation (BOD/ThOD) of DEV 2008-016 and sodium acetate in the closed bottle test inoculated with seawater

 

Time (days)

Oxygen consumption (mg/L)

Biodegradation (%)

Test

Acetate

Test

Acetate

0

0.0

0.0

0

0

7

1.8

4.2

51

78

14

2.2

4.5

63

83

21

2.2

4.6

63

85

28

2.6

4.6

74

85

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
DEV 2008-016 is degraded 74% at 28 days. It is therefore considered readily biodegradable.
Executive summary:

In order to assess the biotic degradation in seawater, a biodegradability test was performed which allows the biodegradability to be measured in seawater. The biodegradability was determined in the Closed Bottle test performed according to slightly modified OECD Test Guidelines, and in compliance with the OECD principles of Good Laboratory Practice.

DEV 2008 -016 did not cause a reduction in the endogenous respiration. The test substance is therefore considered to be non-inhibitory to the inoculum.

DEV 2008 -016 was biodegraded 74% at day 28 in the Closed Bottle test. Hence this substance should be classified as readily biodegradable.

The test is valid as shown by an endogenous respiration of 1.0 mg/L and by the total mineralisation of the reference compound, sodium acetate. Sodium acetate was degraded 85% of its theoretical oxygen demand after 28 days. Finally, the most important criterion was met by oxygen concentrations >0.5 mg/L in all bottles during the test period.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
September - October 1997
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study was conducted according to a standard guideline without deviations from the protocol, but it was not conducted under GLP guidelines.
Justification for type of information:
The justification for read across is provided as an attachment in IUCLID Section 13.
Reason / purpose:
read-across: supporting information
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
no
Principles of method if other than guideline:
The test included two consecutive 41-day phases. The first phase of the test was conducted following the OECD Guideline 301 F (Ready Biodegradability Test) and using a non acclimated, domestic, sewage sludge inoculum, but extending the duration to 41 days. The second phase of the test was conducted following the OECD Guideline 301 F (Ready Biodegradability Test), and using the day 41 acclimated inoculum from the first phase of the test, with a duration of another 41 days.
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
The non acclimated activated sludge inoculum used in this study was obtained from a domestic wastewater treatment plant, in New Jersey, USA.
Duration of test (contact time):
37 d
Initial conc.:
58 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
Triplicate test systems were used to evaluate the biodegradability of the test substance at a concentration of 58 mg/L. Duplicate test systems were used to evaluate the positive control substance at approximate concentrations of 51 mg/L. Blank test systems, which did not contain the test or positive control substance, were run concurrently.
Reference substance:
benzoic acid, sodium salt
Preliminary study:
A preliminary study was not conducted.
Parameter:
% degradation (O2 consumption)
Value:
1
St. dev.:
0.08
Sampling time:
8 d
Parameter:
% degradation (O2 consumption)
Value:
9.4
St. dev.:
0.19
Sampling time:
19 d
Parameter:
% degradation (O2 consumption)
Value:
10.6
St. dev.:
0.11
Sampling time:
20 d
Parameter:
% degradation (O2 consumption)
Value:
17.7
St. dev.:
0.52
Sampling time:
28 d
Parameter:
% degradation (O2 consumption)
Value:
24.5
St. dev.:
1.23
Sampling time:
37 d
Details on results:
The test material was not readily biodegradable. The test material reached approximately 10% biodegradation on day 20. A half-life was not determined. By Day 37, test termination, the average percent biodegradation of the triplicate test systems was 25%.

Biodegradation was based on oxygen consumption and the theoretical oxygen demand of the test substance was calculated using results of an elemental analysis of the test substance.

Interval results for the test substance are as follows:

Day % Biodegradation
(mean of triplicate systems)

8 1.0
19 9.4
20 10.6
28 17.7
31 20.1
37 24.5

Results with reference substance:
The reference substance biodegraded to an extent of 94% after 28 days. By Day 4, >60% biodegradation of the positive control was observed, which meets the guideline requirement.
Validity criteria fulfilled:
yes
Interpretation of results:
inherently biodegradable
Conclusions:
The test substance biodegraded to an extent of 18% after 28 days and 25% after 37 days.
Executive summary:

The test substance biodegraded to an extent of 18% after 28 days and 25% after 28 days in a test of ready biodegrdability. These results suggest that the test substance can be characterized as inherently biodegradable.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Information on substance provided by MSDS (provided by the manufacturer when asked). However, the information on the inoculum remains insufficient.
Justification for type of information:
The justification for read across is provided as an attachment in IUCLID Section 13.
Reason / purpose:
read-across: supporting information
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
no
Principles of method if other than guideline:
Guideline study
GLP compliance:
yes
Remarks:
Accredited by the Italian Ministry of Health
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
no data
Oxygen conditions:
aerobic
Inoculum or test system:
not specified
Details on inoculum:
no data
Duration of test (contact time):
> 28 d
Initial conc.:
44.6 - 46.4 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Additional substrate: none
- Solubilising agent (type and concentration if used): none
- Test temperature: 20-25°C
- Aeration of dilution water: No

TEST SYSTEM
- Number of culture flasks/concentration: 2
- Measuring equipment: Manometric respirometer.
- Test performed in closed vessels due to significant volatility of test substance: Yes
- Details of trap for CO2 and volatile organics if used: soda lime

SAMPLING
- Sampling frequency: every 2 to 3 days

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes
- Abiotic sterile control: No
- Toxicity control: No
- Other: Reference test using sodium benzoate


STATISTICAL METHODS:
Graphical
Reference substance:
benzoic acid, sodium salt
Preliminary study:
None
Parameter:
% degradation (O2 consumption)
Value:
ca. 82
Sampling time:
24 d
Parameter:
% degradation (O2 consumption)
Value:
> 81 - < 83
Sampling time:
24 d
Details on results:
% biodeg Test 1 = 58.3% on day 10; 81.4% on day 24
% biodeg Test 2 = 60.6% on day 10; 81.6% on day 24
Lag period 2 d
Results with reference substance:
87% in 14 d; 91% in 24 d

Date

Day

Test 1

(vol)

Test 2

(vol)

b1 (vol)

b2

(vol)

Ref.

(vol)

Bar.

(vol)

Test 1

Bar.

Test 2

Bar.

b1‑

Bar.

b2 -

Bar.

ref -

Bar.

Room

temp. (C)

P atm.

mmHg

al

(mg 02)

a2

(mg 02)

b1

(mg 02)

b2

(mg 02)

r

(mg 02)

13.07.94

0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0,0

0.0

0.0

0.0

24.2

752.6

0.00

0.00

0.00

0.00

0.00

14.07.94

1

2.0

2.0

0.0

0.0

11.0

-3.0

5.0

5.0

3.0

3.0

14.0

21.0

760.8

6.39

6.39

3.83

3.83

17.90

16.07.94

3

21.5

20.5

4.0

5.0

20.5

-1.0

22.5

21.5

5.0

6.0

21.5

20.0

752.0

28.95

28.95

6.43

7.72

27.66

19.07.94

5

28.5

28.5

1.0

1.0

21.5

-7.0

35.5

35.5

8.0

8.0

28.5

24.0

748.3

44.54

44.54

10.04

10.04

35.76

21.07.94

8

35.5

36.5

1.0

1.0

22.5

-8.0

43.5

44.5

9.0

9.0

30.5

22.0

747.8

55.10

56.37

11.40

11.40

38.63

23.07.94

10

42.5

32.5

4.0

5.0

26.5

-4.5

47.0

47.0

8.5

9.5

31.0

24.0

755.4

59.54

59.54

10.77

12.04

39.27

26.07.94

13

45.5

46.5

2.0

2.0

25.5

-8.0

54.5

54.5

10.0

10.0

33,5

23.0

747.5

67.40

68.66

12.60

12.60

42.20

28.07.94

15

54.5

55.5

9.0

11.0

32.5

0.0

55.5

55.5

9.0

11.0

32.5

22.0

752.4

69.47

70.75

11.47

14.02

41.43

30.07,94

17

56.0

57.0

9.0

10.0

33.0

0.0

56.0

57.0

9.0

10.0

33.0

25.0

752.3

70.28

75.53

11.29

12.55

41.41

02.08.94

20

61.5

60.5

11.0

11.0

34.5

1.0

60.5

59.5

10.0

10.0

33.5

25.0

753.3

76.03

74.77

12.57

12.57

42.10

06.08.94

14

59.0

57.0

5.0

6.0

30.0

-5.0

64.0

62.0

10.0

11.0

35.0

24.0

749.7

80.45

77.94

12.57

13.83

44.00

16.08.94

34

66.5

64.5

11.0

12.0

35.5

1.5

65.0

63.0

13

10.5

34.0

24.0

753.5

82.14

79.61

12.00

13.27

42.96

20.06.94

38

67.0

65.0

13.0

13.0

37.0

3.0

64.0

62.0

10.0

10.0

34.0

24.0

754.3

80.96

78.43

12.65

12.65

43.01

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The test substance was readily biodegradable under the conditions of the study meeting the 10 d window. Validity criteria as set out in the OECD Guidelines were met but many critical details were missing, such as the conditions of the study notably the source and treatment of the inoculum.
Executive summary:

This study was conducted according to the ISO Guideline N. 9408 and OECD Guidelines N.301 F for testing chemicals and under GLP. Biodegradability was assessed by means of manometric respirometry. A measured volume of inoculated medium containing a known amount of test substance is stirred in a closed flask. The consumption of oxygen was determined from the reduction in volume of the air contained in the apparatus. Evolved CO2 was adsorbed in soda lime. The amount of oxygen taken up by the substance (corrected for blank) was expressed as a percentage of the theoretical oxygen demand calculated from the formula of the compound . A reference substance was run in parallel for checking the inoculum. The test substance was readily biodegradable under the conditionsof the study meeting the 10 d window. Validity criteria as set out in the OECD Guidelines were met but many critical details were missing, such as the conditions of the study notably the source and treatment of the inoculum.

Description of key information

Hydrocarbons, C14-C20, aliphatics (≤2% aromatics) were found to be readily biodegradable (biodegradation > 60% ThOD) in an OECD 306 ready biodegradability test. Taking into account that all those substances have been found biodegradable in seawater 306 test, this is taking over all screening tests results and lead to the conclusion that all the substances belonging to this category with the same properties and are therefore considered readily biodegradable.

Hydrocarbons, C12-C16, isoalkanes, cyclics, <2% aromatics biodegraded to an extent of 18% after 28 days and 25% after 28 days in a test of ready biodegradability. These results suggest that Hydrocarbons, C12-C16, isoalkanes, cyclics, <2% aromaticscan be characterized as inherently biodegradable.

Hydrocarbons, C14-C18, n-alkanes, isoalkanes, cyclics, ≤2% aromatics was biodegraded 74% at day 28 in a Closed Bottle test. Hence this substance should be classified as readily biodegradable.

 

Hydrocarbons, C14-C16, n-alkanes, <2% aromatics was found to be readily biodegradable under the conditions of an OECD 301 study meeting the 10-d window.

 

The biodegradation prediction by BIOWIN does not lead to the conclusion that Icosane would be persistent.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

Hydrocarbons, C14-C20, aliphatics (≤2% aromatics) were found to be readily biodegradable (biodegradation > 60% ThOD) in an OECD 306 ready biodegradability test. Taking into account that all those substances have been found biodegradable in seawater 306 test, this is taking over all screening tests results and lead to the conclusion that all the substances belonging to this category with the same properties and are therefore considered readily biodegradable.