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Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
13.11.2009 to 14.12.2009
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2009
Report Date:
2009

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
impurity
Test material form:
solid
Specific details on test material used for the study:
Batch no.: 17399/38 SAAL
Composition 97.26 % Benzophenone methacrylate, 1.95 % Benzophenone acetate
Storage: In a container filled by approx. 90% at a temperature not exceeding 30 °C.

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
Not adapted activated sludge from the aeration tank of the ARA Werdhölzli (CH-8048 Zurich), a municipal biological waste water treatment plant.
30 mg/1 dry matter in the final mixture.
Duration of test (contact time):
28 d
Initial test substance concentrationopen allclose all
Initial conc.:
99.3 mg/L
Based on:
ThOD
Initial conc.:
43.5 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
DOC removal
Details on study design:
TEST CONDITIONS
- Composition of medium: Aerobic mineral salts medium prepared with deionised water (conductivity: <1.5 µS/cm; DOC: < 0.3 mg/L
- Test temperature: 22 ±1.0 °C
- pH: 7.4 ± 0.2
- pH adjusted: yes with NaOH or H2SO4 if necessary
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 500 mL closed glass bottle (tightly closed with a butyl rubber stopper) containing a total volume of test solution of 200 mL. The
bottles were equipped with stirring rods and butyl rubber quivers which contain 2 pellets of sodium hydroxide eachto absorb the produced C02 from the head space.
- The respirometric activity was measured as pressure change. Because the formed C02 is adsorbed, 0 2 consumption leads to a pressure decrease, which is recorded by the OxiT op®-C measuring head (WfW Wissenschaftlich-T echnische Werkstatten
GmbH & Co. KG, DE-82362 Weilheim).
Dissolved organic carbon (DOC) was determined in duplicate with a Shimadzu TOC-5000A or TOC-5050A TOC-Analyzer using the NPOC-mode. For each determination 3 single injections were performed.
The samples from the individual test vessels were centrifuged (15 min at 3500 g) and acidified to pH <2. Prior to analysis the samples were sparged with CO2 free high purity air for 5 min to remove inorganic carbon.
CONTROL AND BLANK SYSTEM
- Inoculum blank: containing inoculum and test medium (2 replicates)
- Abiotic sterile control: containing test substance, test medium and 0.2 mM HgCl2 as sterilizing agent to prevent microbial decomposition
- Toxicity control: containing inoculum + test medium+ test substance+ sodium benzoate as ready biodegradable reference compound

Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradationopen allclose all
Key result
Parameter:
% degradation (O2 consumption)
Value:
78.5
Sampling time:
28 d
Parameter:
% degradation (O2 consumption)
Value:
6
Sampling time:
4 d
Parameter:
% degradation (O2 consumption)
Value:
44.2
Sampling time:
8 d
Parameter:
% degradation (O2 consumption)
Value:
60.3
Sampling time:
12 d
Parameter:
% degradation (O2 consumption)
Value:
64.3
Sampling time:
14 d
Details on results:
The biodegradability of 4-(Methacryloyloxy)benzophenone based on 02 consumption was calculated to be 78% after 28 days as compared to the theoretical oxygen demand (ThOD).
The biodegradation of 4-(Methacryloyloxy)benzophenone reached 67% at the end of the 10-d window.
Biodegradation of the test substance was observed after a lag phase of 2 days.
The procedure control sodium benzoate reached 86% biodegradation after 14 days,thus confirming suitability of inoculum and test conditions.
The calculated biodegradation based on DOC measurement reached 97% for 4-(Methacryloyloxy)benzophenone and 100% for sodium benzoate. The data show that the consumed 02 was used for partial mineralization of the test compound,
since the determined degradation values based on BOD were lower as compared to those based on DOC.
Since more than 25% degradation was observed in the toxicity control, a toxicity of 4-(Methacryloyloxy)benzophenone under the test conditions can be excluded.
4-(Methacryloyloxy)benzophenone was not abiotically degraded (by processes using 02) during the whole test period of 28 days in the absence of microorganisms as confirmed by the determinations of the 02 concentrations.
4-(Methacryloyloxy)benzophenone reached the pass level of 60% for ready biodegradability in the Manometric Respirometry Test within the 10-d window and, therefore, can be termed as readily biodegradable.

BOD5 / COD results

Results with reference substance:
The procedure control sodium benzoate reached 86% biodegradation after 14 days,thus confirming suitability of inoculum and test conditions.

Any other information on results incl. tables

O2 uptake of the test units, the inoculum blank and the corresponding degradation data (test suspension with 78.8 mg/l)

 

Inoculum blank*

Test unit no. 1

Containing test material

Test unit no. 1

Containing test material

 

Time

(days)

BOD

(mg O2/l)

BOD

(mg O2/l)

Degradation

%

BOD

(mg O2/l)

Degradation

%

Mean degradation of no. 1+2

(%)

0

0.0

0.0

0.0

0.0

0.0

0.0

1

4.0

6.0

2.0

2.0

-2.0

0.0

2

8.0

8.0

0.0

4.0

-4.0

-2.0

3

10.0

20.0

10.1

12.0

2.0

6.0

4

12.0

22.0

10.1

14.0

2.0

6.0

5

14.0

26.0

12.1

18.0

4.0

8.1

6

13.0

26.0

13.1

32.0

19.1

16.1

7

14.0

38.0

24.2

53.9

40.2

32.2

8

16.0

59.9

44.2

59.9

44.2

44.2

9

16.0

65.9

50.2

63.9

48.2

49.2

10

16.0

73.9

58.3

67.9

52.3

55.3

11

17.0

77.9

61.3

71.9

55.3

58.3

12

18.0

81.9

64.3

73.9

56.3

60.3

13

18.0

83.9

66.4

77.9

60.3

63.3

14

18.0

85.9

68.4

77.9

60.3

64.3

15

20.0

87.9

68.4

83.9

64.3

66.4

16

20.0

89.9

70.4

85.9

66.4

68.4

17

19.0

91.9

73.4

87.9

69.4

71.4

18

20.0

91.9

72.4

89.9

70.4

71.4

19

20.0

93.9

74.4

89.9

70.4

72.4

20

20.0

93.9

74.4

91.9

72.4

73.4

21

20.0

95.9

76.4

93.9

74.4

75.4

22

22.0

95.9

74.4

91.9

70.4

72.4

23

21.0

97.9

77.4

95.9

75.4

76.4

24

22.0

99.9

78.4

93.9

72.4

75.4

25

22.0

99.9

78.4

97.9

76.4

77.4

26

22.0

99.9

78.4

95.9

74.4

76.4

27

22.0

99.9

78.4

97.9

76.4

77.4

28

23.0

99.9

77.4

102.0

79.5

78.5

* Mean of two replicates

** The calculation is based on the nominal concentration of the test substance of 43.5 mg/l and the theoretical O2 demand (ThOD) in mg O2/mg test substance of 2.283

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
4-(Methacryloyloxy)benzophenone reached 67 % of degradation at the end of the 10 -d window and it reached the pass level of 60 % for ready biodegradability and is therefore classified as ready biodegradable in the Manometric Respiratory Test.
Executive summary:

In a valid guideline study according to OECD 301 F (manometric respiratory test) 4-(Methacryloyloxy)benzophenone was exposed to microorganisms derived from activated sludge of a muncipal sewage treatment plant under aerobic static conditions. The biodegradability of 4-(Methacryloyloxy)benzophenone was determined to be 78 % after 28 days based on O2 consumption as compared to the theoretical O2 demand (ThOD). The positive control sodium benzoate reached 86% biodegradation after 14 days, confirming of suitability of inoculum and test conditions.

Since 4-(Methacryloyloxy)benzophenone reached 67 % of degradation at the end of the 10 -d window it reached the pass level of 60 % for ready biodegradability and is therefore classified as ready biodegradable in the Manometric Respiratory Test.