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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
The inoculum came from the activated sludge of the biological wastewater treatment plant from Abidos (France, 64). The effluent, obtained one day before seeding the flasks, was centrifuged at approximately 20°C for 10 min at 1000 g; the base was re-suspend ed in dilution water in order to keep the concentration unchanged with respect to the sample. The inoculum was preconditioned (aeration) until the flasks were inoculated. The amount of dry material in the inoculum, determined by desiccation at 105 °C until a constant weight is obtained, was 7.17 g/L.
Duration of test (contact time):
28 d
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
Convenient amounts of TETRAMETHYLTHIURAM MONOSULFIDE are directly pour into flasks: 100 mg/L, i.e. 25 mg, corresponding to a theoretical O2 mass of 46 mg per flask (ThOD 1.843 mg O2/mg). A parent solution of sodium benzoate in the dilution water to 2.5 mg/mL, was used in a proportion of 10 mL for 250 mL of dilution water, i.e. 25 mg, corresponding to a theoretical O2 mass of 41.65 mg per flask (ThOD 1.67 mg O2/mg). In the inhibition monitoring flask, equivalent quantities of test and reference items are introduced. For this flask, the corresponding theoretical mass of O2 is 87.7 mg per flask. The flasks were installed in the respirometer where the stirring system was started. After a waiting period of approximately 2 hours, which is necessary to reach the thermal equilibrium of the solutions at a temperature of 22 ± 1°C, the aerated inoculum, prec onditioned if required, is added to all the flasks that are then plugged.
Reference substance:
benzoic acid, sodium salt
Preliminary study:
No preliminary study was performed.
Test performance:
Validity criteria were fulfilled. See "Any other information on Results incl. tables"
Key result
Parameter:
% degradation (CO2 evolution)
Value:
0
Sampling time:
28 d
Details on results:
The calculated theoretical oxygen demand of TETRAMETHYLTHIURAM MONOSULFIDE is 1.843 mg O2/mg. This theoretical oxygen demand is calculated by assuming formation of ammonium, water and carbon dioxide (no nitrification was observed).

As no biodegradation was observed, the latency phase was not determined. TETRAMETHYLTHIURAM MONOSULFIDE did not inhibit the micro-organisms as shown by the toxicity control flask where biodegradation percentage is already 40 %, higher than 25 % after 14 days.
Results with reference substance:
The percentage degradation of the reference item reached a level of 88 % by 14 days which is above the requested level of 60 %

Cumulated Biological Oxygene Demand (mg/L O2)

Day

Fb1

Fb2

Average Fb

Fc1

Fc2

Average Fc

Ft1

Ft2

Average Ft

Fi

Fs

0

0

0

0

0

0

0

0

0

0

0

0

1

9,20

10,40

9,8

51,8

52

51,9

2,6

3,1

2,85

48

1,2

2

10,70

12,40

11,55

89,2

92,2

90,7

2,6

3,4

3

83,8

1,2

3

11,80

13,70

12,75

118,8

121,1

119,95

3,2

4,4

3,8

132,3

1,2

4

13,50

14,70

14,1

140,2

137,8

139

4,7

5,6

5,15

144,1

1,2

5

14,20

15,90

15,05

146,4

144,3

145,35

5,4

5,9

5,65

149

1,2

6

14,20

16,20

15,2

150,8

148,6

149,7

5,4

5,9

5,65

150,6

1,2

7

15,00

17,20

16,1

154,7

152,4

153,55

6

7,1

6,55

152,4

1,2

8

16,20

18,20

17,2

157,7

155,6

156,65

6,7

7,9

7,3

153,4

1,2

9

16,20

18,20

17,2

160,5

158,4

159,45

6,7

7,9

7,3

154,8

1,2

10

16,40

18,70

17,55

162,7

160,6

161,65

6,7

7,9

7,3

156

1,2

11

17,60

19,80

18,7

164,6

162,7

163,65

7,7

9,2

8,45

157,4

1,2

12

18,60

20,60

19,6

165,8

164,2

165

8,9

9,6

9,25

158,4

1,2

13

18,60

20,60

19,6

167,3

165,5

166,4

8,9

9,6

9,25

159,7

2,5

14

19,10

21,70

20,4

168,9

167,1

168

9,4

10,7

10,05

161

6,2

15

19,10

21,70

20,4

170,4

167,9

169,15

9,4

10,7

10,05

161,8

8

16

19,10

21,70

20,4

172

168,7

170,35

9,4

10,7

10,05

162,5

8

17

19,70

22,70

21,2

173,1

170

171,55

9,9

11,5

10,7

163,3

8

18

19,70

22,70

21,2

175,1

171

173,05

10,5

11,5

11

164,2

8

19

20,50

23,20

21,85

176,6

172

174,3

10,5

12,3

11,4

164,3

8

20

21,10

23,80

22,45

178,3

173

175,65

11

13

12

165,1

8

21

21,10

23,80

22,45

179,2

173,4

176,3

11,4

13

12,2

165,6

8

22

21,10

24,20

22,65

180

174,2

177,1

12

13,7

12,85

166,2

8,3

23

21,70

24,40

23,05

180,8

174,7

177,75

12

14,2

13,1

166,8

8,7

24

21,70

24,70

23,2

181,8

175,7

178,75

12,5

14,8

13,65

167,1

8,7

25

22,30

25,30

23,8

182,5

176,4

179,45

13,1

15,3

14,2

167,7

8,7

26

22,80

25,60

24,2

183,2

177,1

180,15

13,6

15,6

14,6

168,2

8,9

27

23,40

26,00

24,7

184

178

181

13,6

15,8

14,7

168,8

9,2

28

24,20

26,70

25,45

185,1

178,9

182

14,8

16,9

15,85

169,2

9,6

Validity criteria

The method was applied with respect to the following criteria:

• The difference of extremes of replicate values of the removal of test chemical at the plateau, at the end of the test, or at the end of the 10-d window, was less than 20 %;

• The percentage degradation of the reference item reached a level of 88 % by 14 days which is above the requested level of 60 %;

• The oxygen uptake of the inoculum blank was of about 25 mg O2/L in 28 days, which is below 60 mg O2/L;

• The pH value in the test suspension was 7.55 at day 28 which is in the range of 6-8.5;

• In the toxicity control flasks, containing both the reference item and TETRAMETHYLTHIURAM MONOSULFIDE the percentage biodegradation reached 40 % after 14 days. Since this value is higher than 25%, the test item is not inhibitory for inoculum.

Validity criteria fulfilled:
yes
Remarks:
see "Any other information on Results incl. tables"
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
Under the test conditions, the percentage of biodegradation of Tetramethylthiuram monosulfide reached 0% of the ThOD at the end of the test (28 days). According to OECD guideline 301F, Tetramethylthiuram monosulfide is not readily biodegradable.
Executive summary:

The purpose of this study was to assess the ready biodegradability of the test item according to the OECD guideline 301 F “Ready biodegradability: Manometric Respirometry Test”. According to the OECD guideline 301, the pass level for ready biodegradability is 60% of Theoretical Oxygen Demand (ThOD). This level has to be reached in a 10-d window within the 28-d period of the test. The 10-d window begins when the degree of biodegradation has reached 10% of ThOD and must end before day 28 of the test.

Under the test conditions, the percentage of biodegradation of Tetramethylthiuram monosulfide reached 0% of the ThOD at the end of the test (28 days). According to OECD guideline 301F, Tetramethylthiuram monosulfide is not readily biodegradable.

Tetramethylthiuram monosulfide did not inhibit the micro-organisms as shown by the toxicity control flask where biodegradation percentage is 40% higher than 25% within 14 days.

Description of key information

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

A study was performed according to the OECD guideline 301 F “Ready biodegradability: Manometric Respirometry Test” in order to assess the ready biodegradability of the test item. According to the guideline, the pass level for ready biodegradability is 60% of Theoretical Oxygen Demand (ThOD). This level has to be reached in a 10-d window within the 28-d period of the test. The 10-d window begins when the degree of biodegradation has reached 10% of ThOD and must end before day 28 of the test.

Under the test conditions, the percentage of biodegradation of Tetramethylthiuram monosulfide reached 0% of the ThOD at the end of the test (28 days). According to OECD guideline 301F, Tetramethylthiuram monosulfide is not readily biodegradable.

Tetramethylthiuram monosulfide did not inhibit the micro-organisms as shown by the toxicity control flask where biodegradation percentage is 40% higher than 25% within 14 days.