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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:
07 Feb - 18 Mar 2008
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP - Guideline study
Reason / purpose:
reference to same study
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Qualifier:
according to
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
GLP compliance:
yes (incl. certificate)
Remarks:
Hessisches Ministerium fur Umwelt, ländlichen Raum und Verbraucherschutz, Wiesbaden, Germany
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: sewage plant Darmstadt, Germany
- Preparation of inoculum for exposure: the aerobic activated sludge was washed by centrifugation and the supernatant liquid phase was decanted. The solid material was re-suspended in tap water and centrifuged again. The procedure was repeated 3 times. The sediment was re-suspended in test water and aerated for 2 d. An aliquot of the final sludge suspension was weighed, dried and the ratio of wet sludge to dry weight was determined. Based on this ratio, aliquots of 1.5 g dry material/L were mixed with test water. This suspension was used for the experiment.
Duration of test (contact time):
28 d
Initial conc.:
102 mg/L
Based on:
test mat.
Initial conc.:
96 mg/L
Based on:
other: ThOD(NH4)
Initial conc.:
96 mg/L
Based on:
other: ThOD(NO3)
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: according to guideline
- Test temperature: 22 °C (test flasks were incubated in a climatised room under continuous stirring)
- pH: 7.6 (measured at the start of the test), 6.9-7.7 (measured at the end of the test)
- Continuous darkness: yes
- Other: the solutions were dispersed by stirring to achieve a homogeneous solution of the test item

TEST SYSTEM
- Culturing apparatus: Manometric Test System with test flask containing a volume of approx. 500 mL (BSB Seonsomat system, Aqualytic Langen)
- Number of culture flasks/concentration: 2
- Measuring equipment: BSB/BOD-Sensor-System, Aqualytic, Neu Isenburg, Germany
- Test performed in closed vessels: yes
- Details of trap for CO2: potassium hydroxide solution (45%) was used for trapping the produced carbon dioxide
- Other: a correction for potential uptake of oxygen by nitrification was considered. Therefore, analysis of nitrate and nitrite using ion chromatography was conducted (Dionex DX 120 ion chromatography system - UV detector UVD 340s and AS 50 Autosampler, wavelength: 225 nm, column: IonPac AS4 A-SC 4 mm x 250 mm, eluent: 15 mmol/L KCl in deionised water, eluent flow: 1.5 mL/min, temperature: 10 - 30 °C)

SAMPLING
- Sampling frequency: every day over 28 d
- Sampling method: pressure decrease in the reaction vessels was measured

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2
- Abiotic sterile control: 1, poisoned with HgCl2 (stock solution of 48.84 mg/mL)
- Toxicity control: 1
- Procedure control: 1

Reference substance:
benzoic acid, sodium salt
Remarks:
Loading rate of 102 mg/L, corresponding to an oxygen demand of about 170 mg/L [ThOD(NH4)]
Parameter:
% degradation (O2 consumption)
Value:
85
Sampling time:
28 d
Remarks on result:
other: result expressed as ThODNH4
Details on results:
10-day window passed (69% biodegradation - based on ThOD(NO3) - at the end of the 10-day window )
Test item not inhibitory to the activated sludge microorganisms [78% and 85% biodegradation of the reference item within 14 and after 28 d, respectively, based on ThOD(NH4)]
Results with reference substance:
88% biodegradation after 14 d and to a mean of 92% after 28 d of incubation.

No nitrification occurred as: the concentration of nitrate in the test solution was below the quantification limit (0.05 mg/L). The nitrate concentration in the controls after 28 d of incubation was 11.6 mg/L (mean). The nitrate concentration in the test item treated vessels was 9.1 mg/L (mean).

Table 1: % biodegradation of test item and the toxicity control based on ThOD(NH4)

Time [d]

Test item [%]

Toxicity control [%]

Flask 1

Flask 2

1

1

-2

19

2

13

7

29

3

23

18

49

4

31

29

56

5

41

35

59

6

47

39

63

7

50

43

65

8

56

51

67

9

59

53

69

10

63

57

71

11

67

63

73

12

72

66

75

13

72

69

76

14

74

68

78

15

76

69

79

16

79

72

79

17

79

73

81

18

81

73

82

19

83

75

83

20

83

76

83

21

84

74

83

22

85

78

84

23

84

77

84

24

84

78

85

25

87

78

85

26

86

81

85

27

86

81

85

28

86

83

85

21

84

74

83

22

85

78

84

23

84

77

84

24

84

78

85

25

87

78

85

26

86

81

85

27

86

81

85

28

86

83

85

Table 2: % biodegradation of test item and the toxicity control based on ThOD(NO3)

Time [d]

Test item [%]

Toxicity control [%]

Flask 1

Flask 2

1

1

-2

19

2

13

7

29

3

23

18

49

4

31

29

56

5

41

35

59

6

47

39

63

7

50

43

65

8

56

51

67

9

59

53

69

10

63

57

71

11

67

63

73

12

72

66

75

13

72

69

76

14

74

68

78

15

76

69

79

16

79

72

79

17

79

73

81

18

81

73

82

19

83

75

83

20

83

76

83

21

84

74

83

22

85

78

84

23

84

77

84

24

84

78

85

25

87

78

85

26

86

81

85

27

86

81

85

28

86

83

85

Table 3: Cumulative Biochemical Oxygen Demand (mg O2/L) in test flasks during the test period of 28 d

No of Flask

Time [d]

1

2

3

4

5

6

7

1

2.9

0

2.9

0

45.7

0

53.1

2

16.2

10.3

4.4

2.9

84.1

0

82.6

3

29.5

23.6

7.4

5.9

117

0

139

4

38.3

35.4

10.3

5.9

133

0

161

5

50.1

42.8

11.8

7.4

142

0

171

6

57.5

48.7

13.3

10.3

149

0

183

7

63.4

56

16.2

13.3

155

0

190

8

69.3

63.4

16.2

13,3

158

0

196

9

75.2

67.8

19.2

16.2

162

0

205

10

81.1

73.7

20.6

17.7

164

0

211

11

85.5

79.6

20.6

19.2

168

0

217

12

90

82.6

20.6

19.2

168

0

223

13

90

85.5

20.6

19.2

170

0

227

14

92.9

85.5

20.6

20.6

170

0

231

15

95.9

87

22.1

20.6

171

0

236

16

98.8

90

22.1

20.6

173

0

237

17

100

91.8

23.6

22.1

177

0

242

18

103

92.9

25,1

22.1

177

0

245

19

105

94.4

25.1

22.1

177

0

248

20

106

95.9

26.5

22.1

177

0

249

21

108

95.9

26.5

25.1

177

0

251

22

108

98.8

25.1

25.1

177

0

252

23

108

98.8

26.5

25.1

177

0

254

24

108

100

26.5

25.1

177

0

256

25

111

100

26.5

25.1

180

0

256

26

111

103

26,5

26.5

181

0

258

27

111

103

26.5

26.5

181

0

258

28

111

105

26.5

26.5

183

0

258

Flask 1, 2: Test item

Flask 3, 4: Inoculum control

Flask 5: Reference

Flask 6: Abiotic control

Flask 7: Toxicity control

Table 4: Results of the nitrogen determination

Treatment

Sampling [day]

Nitrite mg/L

Nitrate mg/L

Sample name

Test water

0

n.d.

n.d.

Control1

0

b.q

b.q.

Test item1

0

b.q

b.q.

Control 1

28

b.q

11.89

Control 2

28

b.q

11.27

mean

28

 

11.58

Test item 1

28

b.q.

9.89

Test item 2

28

b.q.

8.41

mean

28

 

9.15

Toxicity control

28

b.q.

8.46

Abiotic control

28

b.q.

b.q.

1measured in separately prepared vessels
b.q. = below limit of quantification (nitrite 0.05 mg/L and nitrate 0.10 mg/L)

Interpretation of results:
readily biodegradable
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
16 Mar - 12 May 1993
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP- Guideline study with acceptable restrictions: data on methods are missing, no information on inoculum available
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Version / remarks:
(1984)
Qualifier:
according to
Guideline:
EU Method C.5 (Degradation: Biochemical Oxygen Demand)
Version / remarks:
(1984)
GLP compliance:
yes (incl. certificate)
Remarks:
RNE (Réseau National d'Essais), France
Oxygen conditions:
aerobic
Inoculum or test system:
not specified
Duration of test (contact time):
28 d
Initial conc.:
20 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Temperature: 21 - 24 °C
- pH: 6.37 - 7.73 (test substance medium), 6.23 - 7.79 (control medium)

SAMPLING
- Sampling frequency: at days 2, 5, 7, 9, 13, 16, 20, 26, 28

CONTROL AND BLANK SYSTEM
- Inoculum control: yes, no data on replicates
- Reference control: yes, no data on replicates

Reference substance:
acetic acid, sodium salt
Remarks:
20 mg/L
Parameter:
% degradation (CO2 evolution)
Value:
67
Sampling time:
28 d
Details on results:
- Carbon content: 57.8%
- ThCO2 calculated: 2.12 mg CO2/mg test substance
- Total production of CO2 in control medium (3 mL) during the study: 19.8 mg CO2
Results with reference substance:
61% biodegradation in 13 d, 100% in 26 d

Table 1: % biodegradation.

Days Test item Reference substance
2 5 16
5 15 33
7 26 44
9 34 55
13 39 61
16 45 70
20 51 92
26 57 100
28 67  -
Interpretation of results:
readily biodegradable, but failing 10-day window
Endpoint:
biodegradation in water: inherent biodegradability
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
16 Dec 2008 - 13 Jan 2009
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP - Guideline study with acceptable restrictions
Qualifier:
according to
Guideline:
other: OECD guideline 306, 'Biodegradability in Seawater- Closed Bottle Method' (OECD 1992)
GLP compliance:
yes
Remarks:
GLP administered by the UK Dept of Health as stated by the study director.
Oxygen conditions:
aerobic
Inoculum or test system:
other: bacterial community in natural seawater
Details on inoculum:
- Source of inoculum/activated sludge: from submersible pump situated on Sutherland’s pier on the west side of Flotta in Scapa Flow
- Method of sampling: seawater is pumped continuously from a depth of 2 m below low water spring tide level, before passing up 1.8 km of plastic pipe to a 20,000 L storage tank. 2 smaller pumps move the water to 3 settlement tanks situated 9 m above floor level.
- Water filtered: yes, 5 - 7 d before test commencement, raw seawater is filtered through 45 μm filter
- Seawater temperature: 6 °C (winter) - 14 °C (summer)
- Salinity of seawater: 34 - 37‰
Duration of test (contact time):
28 d
Initial conc.:
4.549 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Test vessels: 270 - 276 mL glass BOD bottles containing 180 - 184 mL test medium
- Composition of medium: natural seawater
- Test temperature: 19 - 19.9 °C
- Chemical oxygen demand (COD): 1.143 mg O2/mg test item
- Age of seawater: 7 d
- Saturation value for dissolved oxygen at normal atmospheric pressure: 7.45 mg/L

TEST SYSTEM
- Replication / concentration: 3 per timepoint
- Measuring equipment: polarographic electrode
- Test performed in closed vessels: yes

SAMPLING
- Sampling frequency: 7 d intervals
- Sampling method: measurement of dissolved oxygen

CONTROL AND BLANK SYSTEM
- Oxygen blank: 3 per timepoint
- Reference control: 3 per timepoint
- Inhibition control: 3 per timepoint

Reference substance:
benzoic acid, sodium salt
Parameter:
% degradation (O2 consumption)
Value:
60
Sampling time:
28 d
Parameter:
COD
Value:
1.143 g O2/g test mat.
Results with reference substance:
76% biodegradation of sodium benzoate after 14 d and 78% after 28 d.

The test item showed an inhibition of 8% to seawater bacteria. The oxygen blank degradation was within formal limits of acceptability. The soluble reference material, sodium benzoate, degraded by more than 60% in the first 14 d.

Table 1: % degradation of the test and the reference item.

Material  100% BOD Measured BOD after x days [mg/L] Percentage degradation after x days
7 14 21 28 7 14 21 28
Test item 5.2 1.76 2.91 2.68 3.12 34 56 52 60
Test item in inhibition control 7.7 2.88 4.61 4.53 4.65 38 60 59 61
Sodium benzoate 2.5 1.67 1.9 1.94 1.95 67 76 78 78

Table 2: Average barometric pressure corrected dissolved oxygen concentrations (mg O2/L)

Days
0 7 14 21 28
Oxygen consumption blank 7.10 6.89 6.75 6.43 6.25
Sodium benzoate 6.98 5.22 4.85 4.49 4.30
Test item 6.93 5.13 3.84 3.75 3.13
Test item + sodium benzoate 6.93 4.01 2.14 1.90 1.60

Table 3: Average net oxygen consumption (BOD, mg O2/L)

Days
7 14 21 28
Oxygen consumption blank 0.10 0.23 0.55 0.73
Sodium benzoate 1.67 1.90 1.94 1.95
Test item 1.76 2.91 2.68 3.12
Test item + sodium benzoate 2.88 4.61 4.53 4.65
Interpretation of results:
readily biodegradable, but failing 10-day window
Endpoint:
biodegradation in water: screening tests
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
11 Mar- 12 May 2008
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP - Guideline study with acceptable restrictions
Qualifier:
according to
Guideline:
OECD Guideline 311 (Anaerobic Biodegradability of Organic Compounds in Digested Sludge: Measurement of Gas Production)
Version / remarks:
(2006)
Qualifier:
according to
Guideline:
other: ISO Guideline No 11734 "Water quality - Evaluation of the "ultimate" anaerobic biodegradability of organic compounds in digested sludge - Method by measurement of the biogas production".
Qualifier:
according to
Guideline:
ECETOC Anaerobic Biodegradation (Technical Report No. 28)
GLP compliance:
yes (incl. certificate)
Remarks:
Department of Health, Government of the United Kingdom
Oxygen conditions:
anaerobic
Inoculum or test system:
other: anaerobic, domestic sewage sludge
Details on inoculum:
- Source of inoculum/activated sludge: a mixed population of anaerobic sewage sludge microorganisms was obtained on 12 Mar 2008 from the digester stage of the Severn Trent Water Plc sewage treatment plant at Loughborough, Leicestershire, UK, which treats predominantly domestic sewage.
- Preparation of inoculum for exposure: the sample of anaerobic sludge was maintained at 35 °C in a nearly full, loosely stoppered container prior to use. Anaerobic sludge was washed twice by centrifugation and resuspended in culture medium to remove any excessive amounts of dissolved inorganic carbon (DIC) that were present. The headspace of the sample was purged with N2 in order to maintain the inoculum under anaerobic conditions prior to use in the test.
- Initial cell/biomass concentration: 2.11 g suspended solids/L
Duration of test (contact time):
60 d
Initial conc.:
50 other: mg C/L
Based on:
other: TOC
Initial conc.:
142.7 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
inorg. C analysis
Parameter followed for biodegradation estimation:
other: gas volume produced
Details on study design:
TEST CONDITIONS
- Composition of medium: according to guideline
- Other: the redox indicator resazurin (1 mg/L) was used in each vessel to monitor anaerobic conditions
- Test temperature: 35 °C
- Continuous darkness: yes
- pH: 6.3 - 7

TEST SYSTEM
- Flasks: 160 mL Wheaton bottles filled with 100 mL of solution and sealed with Teflon lined silicon septa
- Number of culture flasks/concentration: 3 replicates plus 1 additional replicate for pH and DIC measurements
- Method used to create anaerobic conditions: after preparation, headspace of the test vessels was purged with nitrogen and vessels were sealed with Teflon lined silicon septa and aluminum crimp tops. The vessels were incubated for approx. 1 h at 35 °C to allow equilibration and any excess gas pressure was then released to the atmosphere. Resazurin was used to further monitor anaerobic conditions.
- Test performed in open system: no

SAMPLING
- Sampling frequency: pressure, pH, dissolved oxygen, DIC were measured in the test vessels. On day 0, 1 replicate control, standard, test material and toxicity control vessel were sacrificed for DIC and pH determinations. Pressure readings of all test vessels were recorded on day 0, 1, 7, 14, 21, 28, 35, 42, 49, 56 and 60. Samples for DIC determination were taken from the sacrificed vessels on day 0 and approx. 2 mL from each replicate vessel on day 60.
- Measuring equipment:
- TOC: TOC-5050A TOC analyser (680°C using a platinum catalyst and zero grade air as carrier gas)
- DIC measurement: Shimadzu TOC-VCSH TOC analyser (triplicates of 50 µL sample were injected and measured, sodium carbonate and potassium hydrogen phthalate standards were used)
- Pressure: Watson-Smith hand held precision pressure meter attached to a miniature three-way valve and syringe needle. The pressure readings (bar) were converted to gas volumes by substituting the pressure readings into the calibration curve for the Watson-Smith pressure meter.
- pH: WTW pH 340i pH meter
- Determination of dry weight of sludge: by taking one sample from the initial anaerobic sludge
- Other: test vessels were shaken by hand at least 3 times/week to equilibrate gas produced by degradation and vented to atmosphere after each reading. TOC of the test material was measured prior to the test in order to calculate the required concentration for the test.

CONTROL AND BLANK SYSTEM
- Inoculum control: 6 replicates plus 1 additional replicate for pH and DIC measurements
- Reference control: 3 replicates plus 1 additional replicate for pH and DIC measurements
- Toxicity control: 3 replicates plus 1 additional replicate for pH and DIC measurements

Reference substance:
benzoic acid, sodium salt
Parameter:
other: calculated from the volume of gas produced
Value:
103
Sampling time:
60 d
Parameter:
other: DIC formation
Value:
104
Sampling time:
60 d
Details on results:
Degradation values in excess of 100% were considered to be due to sampling/analytical variation.
The test material did not inhibit anaerobic micoorganisms at the selected test concentration (85% degradation took place after 60 d in the toxicity control based on volume of gas produced and 87% based on DIC formation).
Results with reference substance:
Sodium benzoate attained 99% degradation after 60 d calculated from the volume of gas produced and 91% degradation calculated from DIC formation thereby confirming the suitability of the inoculum and test conditions whereby the standard material must have a plateau phase that represents 60% biodegradation for the test to be valid.

Observations made throughout the test period confirmed that anaerobic conditions were maintained in all test vessels over the 60 d period.

Test 1: % degradation values (calculated from volume of gas produced).

Day

% Degradation

Sodium Benzoate

Test Material

Test Material + Sodium Benzoate, Toxicity Control

1

0

0

0

7

0

0

0

14

0

0

0

21

0

25

11

28

41

66

36

35

98

112

72

42

98

119

76

49

98

118

84

56

99

115

88

60

99

103

85

Table 2: Dissolved inorganic carbon values.

Test Vessel

Dissolved Inorganic Carbon (mg C/L)

 

 

Day 0*

Day 60

Control

R1

1.92

74.20

 

R2

-

63.29

 

R3

-

69.88

 

R4

-

68.35

 

R5

-

62.84

 

R6

-

82.22

 

Mean

-

70.13

Sodium Benzoate

R1

1.37

71.47

 

R2

-

66.70

 

R3

-

67.80

 

Mean

-

68.66

Test Material

R1

2.56

71.86

 

R2

-

82.54

 

R3

-

65.30

 

Mean

-

73.23

Test Material plus Sodium Benzoate, Toxicity Control

R1

2.42

76.86

 

R2

-

83.94

 

R3

-

75.40

 

Mean

-

78.73

The % carbon content of the test material, based on the mean of the 3 TOC replicate results, was determined to be 34.98%.

Interpretation of results:
other: anaerobic biodegradable within 60 d in digested sludge
Endpoint:
biodegradation in water: ready biodegradability
Adequacy of study:
supporting study
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: Insuficient data available (only key results are summarized in the report, no description of the methods, no reference on the inoculum)
Qualifier:
according to
Guideline:
OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))
GLP compliance:
not specified
Oxygen conditions:
aerobic
Parameter followed for biodegradation estimation:
O2 consumption
Parameter:
% degradation (O2 consumption)
Value:
82.9
Sampling time:
23 d
Parameter:
COD
Value:
1 122 other: mg O2/L
Parameter:
BOD5
Value:
460 mg O2/g test mat.

COD was determined with the dichromate method

Interpretation of results:
readily biodegradable

Description of key information

D-Glucopyranose, oligomeric, undecyl glycoside (CAS 98283-67-1) is readily biodegradable according to OECD criteria

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

Five studies are available on the biodegradability of D-Glucopyranose, oligomeric, undecyl glycoside (CAS 98283-67-1).

 

In a study by IBACON GmbH (2008) the ready biodegradability of the test substance according to the OECD guideline 301 F (and GLP) was investigated. This study was chosen as the key study. A non-adapted, activated sludge from a domestic sewage treatment plant was used as inoculum and was exposed to an initial nominal test substance concentration of 102 mg/L (96 mg/L based on ThOD(NH4)). After 28 d test duration, 85% degradation of the test substance (ThOD(NH4) based on O2 consumption) was observed. The 10-day window criterion was fulfilled. A toxicity control containing both, reference substance (sodium benzoate, 170 mg/L based on ThOD(NH4)) and test substance did not indicate inhibitory effects to the inoculum, as 78% biodegradation, based on ThOD(NH4), of the reference item took place within 14 d.

 

A supporting study is available, conducted according to the OECD guideline 306 and GLP, in which a bacterial community from natural seawaters was exposed to an initial test item concentration of 4.549 mg/L (nominal) (Opus Plus Limited, 2009). Seawater was used as the test medium. Benzoic acid served as the reference substance. 60% biodegradation (based on O2 consumption) was reported within 28 d test duration but the 10-day window criterion was not met. Furthermore, the test item showed an inhibition of 8% to the seawater microbial community.

 

The biodegradation of D-Glucopyranose, oligomeric, undecyl glycoside was also tested under anaerobic conditions in a study conducted according to OECD guideline 311, ISO No 11734, ECETOC anaerobic biodegradation (Technical report No. 28) and GLP (Safepharm Laboratories Limited, 2008). Anaerobic, domestic sewage sludge was exposed to 142 mg/L test item (nominal, corresponding to 50 mg/L TOC) for 60 d. Inorganic carbon analysis as well as gas volume production were followed in order to estimate biodegradation. Benzoic acid was used as a reference substance and the redox indicator resazurin was applied to monitor anaerobic conditions. 103% of the test item was biodegraded based on calculations from the volume of gas produced, while results based on DIC formation showed 104% biodegradation. Degradation values in excess of 100% were considered to be due to sampling and analytical variation. A toxicity control containing both, reference substance and test substance did not indicate inhibitory effects to the inoculum (85% degradation after 60 d based on volume of gas produced and 87% based on DIC formation).

 

An additional supporting study is available in which D-Glucopyranose, oligomeric, undecyl glycoside according to the OECD guideline 301 B, the EU Method C.5 and GLP was tested (SEPC, 1993). A 20 mg/L initial test substance concentration was used and the biodegradation was followed by CO2 evolution. Acetic acid was used as the reference substance, which was degraded to 61% in 13 d and 100% after 26 d. 67% biodegradation of the test item was reported after 28 d test duration but the 10-day window criterion was not met.

 

A brief summary of a study conducted with the test item according to the OECD guideline 301 C and GLP is available by Hygiene Institut (1999), in which 82.9% biodegradation of the test item within 23 d based on O2 consumption is reported. However, insufficient data on methodology and results were provided and the study was considered as not assignable (RL4) and not used for further risk assessment or classification purposes.

 

In summary, based on the data available in the above described studies D-Glucopyranose, oligomeric, undecyl glycoside (CAS 98283-67-1) is considered to be readily biodegradable under aerobic conditions. Results with the key study are corroborated by the supporting data. The test item was found to be biodegradable both in fresh- and saltwater environments. A slight inhibition of sea water microorganisms was nevertheless observed. The substance was also biodegraded by anaerobic sewage sludge under anoxic conditions.