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Hydrolysis

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Reference
Endpoint:
hydrolysis
Remarks:
Degradation assay in a natural river water based on an adaptation of the OECD 111 guideline.
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
2019
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Justification for type of information:
See attached justification
Qualifier:
equivalent or similar to guideline
Guideline:
other: The protocol described a degradation assay in a natural river water based on an adaptation of the OECD 111 guideline.
Deviations:
yes
Remarks:
See section "Principles of method if other than guideline"
Principles of method if other than guideline:
METHOD
The purpose of this study was to check the degradation of the test item in a natural river water. The water was treated with the test item (at 300 µg/L nominal concentration) and incubated under constant agitation in the dark at a constant temperature of 12°C. In addition, a biotic control (river water and acetone only) and an abiotic control (autoclaved river water and acetone) were also prepared. After appropriate time intervals, the solution was analysed for the test item and its degradation products.

DEVIATION(S)
The following deviations of the experimental procedure were observed in this study:
- One replicate (d) was added to each treatment for the pH and dissolved oxygen determination, in a way to avoid a contamination of the flasks used for the test item determination.
- The pH and dissolved oxygen determination at T0 (i.e. immediately after the test item introduction) was not performed for the blank control (Fb) and for the test item flask (Ft) but was realised a few hours later for internal organisation reasons
- The metrological control of the climatic chamber used was not checked at the test temperature of 12°C. To confirm the temperature was compliant for all test flasks, 2 data loggers were used and placed close to the flasks, in a way to create a circle around the test flasks.
These deviations were considered to have not affected the outcome or the achievement of the study objectives

The following deviations of the analytical method validation procedure were observed in this study:
Due to the test item rapid structure evolution (minute to hour range when it is dissolved in organic or aqueous mixtures), it was not possible to fulfill the following analytical method criteria:
- Storage stability of the solutions
- System stability of the solutions
- Control of the test solutions dilutions
As a consequence, the test item concentrations obtained using this method are given for information purposes only and should be regarded as trends. It should be noted that this rapid structure evolution in solvents including water is an intrinsic property of the substance that could not be technically overcome despite technical efforts.
GLP compliance:
yes (incl. QA statement)
Radiolabelling:
no
Analytical monitoring:
yes
Details on sampling:
- Sampling intervals for the parent/transformation products:
7-8 samplings during the test

- Sampling method:
Individual replicate test samples (replicates a, b & c) were removed and the contents analysed at each of the sampling times. pH and dissolved oxygen concentration was also measured in the dedicated vessel (replicate d). Due to a long analytical run time, Fb & Ft flasks were started on the same day (09/04/19) while Fa were started next day on 10/04/19. The sampling programme was set so that a significant number of analysis was available while the test item disappearance was faster.

- Sampling intervals/times for pH measurements:
7 samplings during the test

- Sampling intervals/times for sterility check:
Sterility was checked at the end of the assay by microscopic observation

- Sample storage conditions before analysis:
analysis performed shortly after sampling

- Other observation, if any (e.g.: precipitation, color change etc.):
none
Buffers:
The pH of the river water was determined to be 8.0, then adjusted to pH 7.2.
Details on test conditions:
EXPERIMENTAL PROCEDURE

- TEST MEDIUM
The hydrolysis test was conducted using a natural river water freshly collected on 08 April 2019 from the river "Le Gave de Pau" close to the test facility. On arrival at the laboratory, the water (around 10 L) was kept at 12°C until the test was started (i.e. 24 hours for blank controls and test item vessels and 48 hours for abiotic controls). In order to obtain the required sludge suspended solids concentration of 15 mg/L to be used in the experiments, the solid content of the natural water was determined by removing a sub-sample and drying in an oven at approximately 105°C. The suspended solids concentration was determined to be 30.9 mg/L then was subsequently adjusted with dechlorinated water until the required value of 15 mg/L is achieved. The pH was determined to be 8.0, then adjusted to pH 7.2 as required.

- PREPARATION OF TEST SOLUTIONS
In accordance with the sponsor's representative only one concentration of the test item was applied: 4 replicates test vessels (see paragraph ¿1.6) were prepared in the natural river water at 0.3 mg test item/L (nominal concentration) with the help of acetone (1% at a maximum). The test item was directly added to the test flasks. Conditions of the test were determined beforehand with preliminary studies. 4 replicates test vessels containing only river water and acetone (control flasks) were incubated in identical conditions. The potential test item abiotic degradation was assessed: 4 replicates test vessels containing the river water were autoclaved at around 120°C during 20 minutes. After cooling down to room temperature the test item was added at 0.3 mg/L of nominal concentration with the help of acetone. The addition of the test item (T0) was considered as the start of the test period of 30 days.

- ENVIRONMENTAL CONDITIONS
All test flasks were incubated in darkness in a climatic chamber that was maintained at 12°C controlled to +/-1°C over the test period of 30 days, and kept under constant agitation by means of a magnetic stirrer.

Duration:
30 d
pH:
7.2
Temp.:
12 °C
Initial conc. measured:
300 µg/L
Remarks:
A concentration above the water solubility was chosen in order to facilitate the identification and quantification of major transformation products due to analytical limitations. Acetone (max 1%) was used to prepared the initial concentration.
Number of replicates:
4
Positive controls:
no
Negative controls:
yes
Remarks:
In addition to the test item flasks, control flasks with river water and acetone only were also prepared.
Transformation products:
yes
No.:
#1
No.:
#2
No.:
#3
No.:
#4
No.:
#5
No.:
#6
Details on hydrolysis and appearance of transformation product(s):
Degradation products consists of a series of polysulphides expressed in term of Sx with x the number of sulphur atoms in the chain (from 1 to 7 sulphur atoms).
Key result
Temp.:
12 °C
Remarks on result:
other: Based on chromatographic peak areas S7, S8 (DPTH) and S9 will not remain in the environment.
Details on results:
DETERMINATION OF TEST ITEM
The results below are expressed in term of Sx with x the number of sulphur atoms in the polysulfide.

- BLANK CONTROL FLASKS (FB)
The results show the test item was detected and quantified at low level in some samples all over the test period, suggesting an analytical contamination with residual test item.

- ABIOTIC CONTROL FLASKS (FA) & TEST ITEM FLASKS (FT)
The test item theoretical concentration of 0.3 mg/L at the beginning of the test is relatively reached: a test item concentration of 0.36 and 0.43 mg/L was determined for Fa & Ft respectively.

Fa : At T0, 6 chromatographic peaks are visible (S4 to S9); the chromatographic peaks S4, S6, S7 and S8 are less visible than equivalent peaks for Ft. From day 6, peaks S6 to S9 are not visible anymore, residuals including peaks S3 to S5, are visible. From day 13, only one replicate vessel had a test item concentration above QL

Ft : At T0, 6 chromatographic peaks are visible (S4 to S9); the chromatographic peaks S4, S6, S7 and S8 are more easily visible than equivalent peaks for Fa. From day 7 to day 14, peaks S7 to S9 are not visible anymore, S4 is predominant but S3, S5 and S6 are still visible. From day 21/22, S3 and S4 are still visible but the test item was not quantifiable. At day 30, only S3 is still visible but the test item was not quantifiable

The test item concentration evolution over time for Ft and Fa treatments suggest a quick decreasing of the test item within a few days.
For some results high RSD were calculating meaning that the mean determined value should be considered with caution


ENVIRONMENTAL CONDITIONS
The ambient temperature during the test was measured as follows: min: 12.1°C, max.: 12.7C.
Measured pH and dissolved oxygen concentration are reported in the section "Any other information on results incl. tables" of this report study record. They were in the following ranges:

- Fb: 7.7 – 7.9 for pH and 7.5 – 8.2 mg O2/L for O2
- Fa: 8.1 – 8.4 for pH and 7.8 – 8.4 mg O2/L for O2
- Ft: 7.8 – 8.3 for pH and 7.7 – 8.3 mg O2/L for O2


Table 3: Sampling program

Sampling

T0

T1

T2

T3

T4

T5

T6

T7

 

Fb

Date

09/04/2019

09/04/2019

10/04/2019

16/04/2019

23/04/2019

30/04/2019

07/05/2019

09/05/2019

 

Hour

13:15

15:45

15:30

14:30

16:30

13:45

10:20

14:40

 

Test item analysis

yes

no

yes

yes

yes

yes

yes

yes

 

O2(mg/L)

ND

7.9

7.7

7.9

7.7

7.5

8.2

7.9

 

pH

ND

7.7

7.9

7.8

7.9

7.9

7.7

7.9

 

Sampling

T0

T1

T2

T3

T4

T5

T6

 

 

Fa

Date

10/04/2019

10/04/2019

16/04/2019

23/04/2019

30/04/2019

07/05/2019

10/05/2019

 

 

Hour

10:30

15:00

10:50

15:00

11:45

10:25

15:55

 

 

Test item analysis

yes

yes

yes

yes

yes

yes

yes

 

 

O2(mg/L)

8.3

7.9

7.8

7.8

7.8

8.2

8.4

 

 

pH

8.6

8.4

8.2

8.3

8.1

8.1

8.1

 

 

Sampling

T0

T1

T2

T3

T4

T5

T6

T7

T8

Ft

Date

09/04/2019

09/04/2019

09/04/2019

09/04/2019

10/04/2019

16/04/2019

23/04/2019

30/04/2019

09/05/2019

Hour

11:20

13:00

14:20

15:45

15:30

11:50

15:30

13:45

14:40

Test item analysis

yes

yes

yes

no

yes

yes

yes

yes

yes

O2(mg/L)

ND

ND

7.9

8.3

7.9

7.9

7.7

7.9

7.9

pH

ND

ND

7.9

8.1

8.3

8

7.8

7.8

8.4

Table 4: Test item determination for blank control (Fb)

Sampling #

Observation time from Start

Replicate

Test item concentration(mg/L)

Mean

SD

RSD (%)

Measure 1

Measure 2

T0

T0

a

<DL

<DL

<DL

NA

NA

b

<DL

<DL

<DL

NA

NA

c

<QL

<QL

<QL

NA

NA

T1

2.5h

a

Not determined at this sampling time

b

c

T2

26.3h

 

1 day

a

<QL

-*

<QL

NA

NA

b

<QL

-

<QL

NA

NA

c

0.025

-

0.025

NA

NA

T3

169.2h

 

7 days

a

<DL

<DL

<DL

NA

NA

b

<DL

<DL

<DL

NA

NA

c

<DL

<DL

<DL

NA

NA

T4

339.2h

 

14 days

a

<DL

<DL

<DL

NA

NA

b

<DL

<DL

<DL

NA

NA

c

<DL

<QL

<QL

NA

NA

T5

504.5h

 

21 days

a

<DL

<DL

<DL

NA

NA

b

<DL

<DL

<DL

NA

NA

c

<DL

<DL

<DL

NA

NA

T6

669.1h

 

28 days

a

<DL

<DL

<DL

NA

NA

b

<DL

<DL

<DL

NA

NA

c

<DL

<DL

<DL

NA

NA

T7

721.4h

 

30 days

a

<DL

<DL

<DL

NA

NA

b

<DL

<DL

<DL

NA

NA

c

<QL

<DL

<QL

NA

NA

< DL (0.006 mg/L): concentration lower than the Detection Limit

< QL (0.020 mg/L): concentration lower than the Quantification Limit

NA: Not Applicable

*no available measure, sample analyses once

Table 5: Test item determination for abiotic control (Fa)

Sampling #

Observation time from Start

Replicate

Test item concentration(mg/L)

Mean

SD

RSD (%)

Measure 1

Measure 2

T0

T0

a

0.378

0.384

0.381

0.004

1.2

b

0.408

0.320

0.364

0.062

17

c

0.352

0.314

0.333

0.027

8.1

T1

4.5h

a

0.127

0.114

0.121

0.009

7.5

b

0.132

0.120

0.126

0.008

6.7

c

0.209

0.099

0.154

0.078

51*

T2

144.3h

 

6 days

a

0.066

0.039

0.053

0.019

36*

b

0.039

0.023

0.031

0.012

38*

c

0.034

0.039

0.036

0.004

10

T3

316.5h

 

13 days

a

<QL

<QL

<QL

NA

NA

b

0.033

0.024

0.029

0.006

22*

c

<QL

<QL

<QL

NA

NA

T4

481.3h

 

20/21 days

a

<DL

<DL

<DL

NA

NA

b

<QL

0.026

0.026

NA

NA

c

<DL

<DL

<DL

NA

NA

T5

647.9h

 

27 days

a

<QL

<QL

<QL

NA

NA

b

0.027

0.023

0.025

0.003

12

c

<QL

<QL

<QL

NA

NA

T6

725.4h

 

30 days

a

<DL

<DL

<DL

NA

NA

b

<DL

<DL

<DL

NA

NA

c

<DL

<DL

<DL

NA

NA

< DL (0.006 mg/L): concentration lower than the Detection Limit

< QL (0.020 mg/L): concentration lower than the Quantification Limit

NA: Not Applicable

Table 6: Test item determination for test item flask (Ft)

Sampling #

Observation time from Start

Replicate

Test item concentration(mg/L)

Mean

SD

RSD (%)

Measure 1

Measure 2

T0

T0

a

0.514

0.400

0.457

0.080

18

b

0.474

0.363

0.419

0.079

19

c

0.478

0.354

0.416

0.088

21*

T1

1.7h

a

0.093

0.106

0.099

0.009

9.2

b

0.090

0.088

0.089

0.001

1.7

c

0.083

0.116

0.100

0.023

23*

T2

3h

a

0.081

0.074

0.078

0.006

7.1

b

0.070

0.079

0.075

0.006

8.7

c

0.063

0.080

0.072

0.012

16

T3

4.4h

a

Not determined at this sampling time

b

c

T4

28.2h

 

1 day

a

0.081

0.089

0.085

0.006

6.8

b

0.080

0.074

0.077

0.004

5.7

c

0.083

0.066

0.074

0.012

16

T5

168.5h

 

 7 days

a

0.080

0.068

0.074

0.008

11

b

0.055

0.058

0.056

0.002

3.8

c

0.042

0.057

0.049

0.011

21*

T6

340.2h

 

14 days

a

0.043

0.034

0.039

0.006

16

b

0.041

0.039

0.040

0.001

2.1

c

0.027

0.029

0.028

0.001

4.8

T7

506.4h

 

21/22 days

a

<QL

<QL

<QL

NA

NA

b

<QL

<DL

<QL

NA

NA

c

<DL

<DL

<DL

NA

NA

T8

723.3h

 

30 days

a

<QL

<DL

<QL

NA

NA

b

<QL

<QL

<QL

NA

NA

c

<QL

<DL

<QL

NA

NA

< DL (0.006 mg/L): concentration lower than the Detection Limit

< QL (0.020 mg/L): concentration lower than the Quantification Limit

NA: Not Applicable

Table 7: Summary for Fa and Ft

Sampling #

Test flask

Date

Test item conc.

(mg/L, mean of replicates)

SD

RSD (%)

T0

Fa

10/04/19

0.359

0.024

6.8

Ft

09/04/19

0.430

0.023

5.4

T1

Fa

10/04/19

0.134

0.018

13.3

Ft

09/04/19

0.096

0.006

6.3

T2

Fa

16/04/19

0.040

0.011

28.1

Ft

09/04/19

0.075

0.003

4.0

T3

Fa

23/04/19

0.029

NA

NA

Ft

ND

ND

NA

NA

T4

Fa

30/04/19

0.026

NA

NA

Ft

10/04/19

0.079

0.006

7.0

T5

Fa

07/05/19

0.025

NA

NA

Ft

16/04/19

0.060

0.013

21.3

T6

Fa

10/05/19

< DL

NA

NA

Ft

23/04/19

0.035

0.007

19.1

T7

Fa

ND

ND

NA

NA

Ft

30/04/19

< QL

NA

NA

T8

Fa

ND

ND

NA

NA

Ft

09/05/19

< QL

NA

NA

< DL (0.006 mg/L): concentration lower than the Detection Limit

< QL (0.020 mg/L): concentration lower than the Quantification Limit

ND: not determined

NA: Not Applicable

Table 8: Peak area for each species

 

C12H20N2S3

C12H20N2S4

C12H20N2S5

C12H20N2S6

C12H20N2S7

C12H20N2S8

C12H20N2S9

Area Sum

Area

S3

S4

S5

S6

S7

S8

S9

Replicate 

a

b

c

a

b

c

a

b

c

a

b

c

a

b

c

a

b

c

a

b

c

a

b

c

Fb (control)

T0   

0

0

0

0

183

238

0

0

0

0

0

0

253

297

296

1515

1714

1171

62

242

79

1830

2435

1786

T1

4

0

115

0

0

169

0

0

0

0

0

0

0

0

556

2902

4630

3583

0

284

329

2905

4914

4751

T2

0

0

0

0

0

0

0

0

0

0

0

0

0

0

84

666

631

542

0

0

0

666

631

626

T4

0

0

0

354

286

530

0

0

138

0

0

0

0

0

229

603

526

976

0

0

125

957

812

1999

T5

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

T6

0

0

0

0

0

0

0

0

0

0

0

0

0

0

3

0

0

0

0

0

0

0

0

3

T7

0

0

0

0

0

0

0

0

0

0

0

145

0

0

0

0

0

0

0

0

0

0

0

145

Ft

(test)

T0

315

212

220

22558

26257

26954

58362

47101

46929

62833

61959

61688

28253

27028

25873

12930

11611

12018

3831

3562

3487

189082

177730

177168

T1

143

110

107

7122

9966

11712

4378

2893

2716

5110

4899

4715

5330

4457

4659

4672

3275

3025

2446

1452

1442

29202

27052

28376

T2

231

277

251

14035

18353

19237

5837

3539

3768

7465

6751

4918

6551

5279

4045

3215

2253

1768

958

691

447

38292

37143

34434

T4

254

361

365

23220

19496

21001

1577

1758

984

1494

1086

676

524

414

151

162

213

100

0

0

0

27231

23327

23277

T5

470

658

675

11425

12286

12505

522

877

628

3116

2234

1238

368

686

161

0

942

0

0

0

0

15901

17682

15206

T6

1120

2245

1702

17600

16439

13278

1063

1204

338

2132

2480

1002

127

475

0

412

618

0

0

106

0

22454

23568

16321

T7

4881

4137

3750

3014

2264

3236

156

512

85

0

211

0

233

460

0

247

492

0

0

59

0

8530

8135

7071

T8

2780

2536

2533

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

2780

2536

2533

Fa

(abiotic)

T0

193

227

153

4666

5712

4050

36429

34028

31307

11442

10980

10642

6771

6985

7944

13877

11916

9002

4021

4095

4001

77400

73942

67099

T1

116

72

92

10487

10330

7958

18749

21742

29322

5042

5628

15191

1315

1072

3761

1301

816

2056

955

765

615

37965

40426

58994

T2

693

1083

520

3242

2680

2552

4104

2156

2402

1275

608

700

430

0

127

1550

0

0

248

0

0

11541

6527

6300

T3

1703

3963

1964

2852

5989

3237

1029

2342

1248

393

609

384

0

0

0

0

184

0

0

0

0

5977

13087

6834

T4

808

808

701

4135

15864

5260

0

0

0

0

0

0

0

824

0

1126

0

0

0

0

0

6069

17496

5962

T5

1883

2405

1271

5378

25572

10029

49

440

185

0

0

0

473

189

128

2244

366

617

0

0

0

10028

28972

12230

T6

1522

2961

4025

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

1522

2961

4025

Table 9 : Relative area percentage

 

C12H20N2S3

C12H20N2S4

C12H20N2S5

C12H20N2S6

C12H20N2S7

C12H20N2S8

C12H20N2S9

Area %

S3

S4

S5

S6

S7

S8

S9

 

Time (h)

a

b

c

a

b

c

a

b

c

a

b

c

a

b

c

a

b

c

a

b

c

Fb
(control)

0.0

0

0

0

0

8

13

0

0

0

0

0

0

14

12

17

83

70

66

3

10

4

26.3

0

0

2

0

0

4

0

0

0

0

0

0

0

0

12

100

94

75

0

6

7

169.3

0

0

0

0

0

0

0

0

0

0

0

0

0

0

13

100

100

87

0

0

0

339.3

0

0

0

37

35

27

0

0

7

0

0

0

0

0

11

63

65

49

0

0

6

504.5

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

669.1

0

0

0

0

0

0

0

0

0

0

0

0

0

0

100

0

0

0

0

0

0

721.4

0

0

0

0

0

0

0

0

0

0

0

100

0

0

0

0

0

0

0

0

0

Ft
(test)

0.0

0

0

0

12

15

15

31

27

26

33

35

35

15

15

15

7

7

7

2

2

2

1.7

0

0

0

24

37

41

15

11

10

17

18

17

18

16

16

16

12

11

8

5

5

3.0

1

1

1

37

49

56

15

10

11

19

18

14

17

14

12

8

6

5

3

2

1

28.2

1

2

2

85

84

90

6

8

4

5

5

3

2

2

1

1

1

0

0

0

0

168.5

3

4

4

72

69

82

3

5

4

20

13

8

2

4

1

0

5

0

0

0

0

340.2

5

10

10

78

70

81

5

5

2

9

11

6

1

2

0

2

3

0

0

0

0

506.4

57

51

53

35

28

46

2

6

1

0

3

0

3

6

0

3

6

0

0

1

0

723.3

100

100

100

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Fa
(abiotic)

0.0

0

0

0

6

8

6

47

46

47

15

15

16

9

9

12

18

16

13

5

6

6

4.5

0

0

0

28

26

13

49

54

50

13

14

26

3

3

6

3

2

3

3

2

1

144.3

6

17

8

28

41

41

36

33

38

11

9

11

4

0

2

13

0

0

2

0

0

316.5

28

30

29

48

46

47

17

18

18

7

5

6

0

0

0

0

1

0

0

0

0

481.3

13

5

12

68

91

88

0

0

0

0

0

0

0

5

0

19

0

0

0

0

0

647.9

19

8

10

54

88

82

0

2

2

0

0

0

5

1

1

22

1

5

0

0

0

725.4

100

100

100

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Relative area percentage is calculated dividing the surface of an individual peak by the Area sum of all the peaks.

Validity criteria fulfilled:
not applicable
Conclusions:
Due to the test item rapid structure evolution (minute to hour range when it is dissolved in organic or aqueous mixtures), it was not possible to fulfill the following analytical method criteria and thus the test item concentrations are given in the present report for information purposes only and should be regarded as trends. It should be noted that this rapid structure evolution in solvents including water is an intrinsic property of the substance that cannot be technically overcome despite technical efforts.

The test item decreasing over time in a natural river water at 12°C until its complete disappearance at day 30 was demonstrated. It should be noted that among the series of polysullphides targeted, the loss rates of the chromatographic peaks of dipentamethylenethiuram pentasulfide (S7), dipentamethylenethiuram hexasulfide (S8) and dipentamethylenethiuram heptasulfide (S9) was higher than the others peaks. Both abiotic control and river water conditions degradation patterns were similar, suggesting a chemical degradation rather than a biological degradation.
Executive summary:

This study was designed tocheck the hydrolysis of the test item in a natural river water according to a degradation assay protocol based on an adaptation of the OECD 111 guideline.

 

A river water freshly sampled was treated with the test item (at 300 µg/L nominal concentration) and incubated under constant agitation in the dark at a constant temperature of 12°C. After appropriate time intervals, the solution was analysed for the test item and its degradation products which consists of a series of polysulphides.

 

Due to the test item rapid structure evolution (minute to hour range when it is dissolved in organic or aqueous mixtures), it was not possible to fulfill the following analytical method criteria and thusthe test item concentrations are given in the present report for information purposes only and should be regarded as trends. 

 

The test item decreasing over time in a natural river water at 12°C until its complete disappearance at day 30 was demonstrated. It should be noted that among the series of polysullphides targeted, the loss rates of the chromatographic peaks of dipentamethylenethiuram pentasulfide (S7), dipentamethylenethiuram hexasulfide (S8) and dipentamethylenethiuram heptasulfide (S9) were higher than the others peaks. Both abiotic control and river water conditions degradation patterns were similar, suggesting a chemical degradation rather than a biological degradation.

Description of key information

Key value for chemical safety assessment

Additional information

This study was designed to check the degradation of the test item in a natural river water according to a degradation assay protocol based on an adaptation of the OECD 111 guideline.

A river water freshly sampled was treated with the test item (at 300 µg/L nominal concentration) and incubated under constant agitation in the dark at a constant temperature of 12°C. After appropriate time intervals, the solution was analysed for the test item and its degradation products which consists of a series of polysulphides.

Due to the test item rapid structure evolution (minute to hour range when it is dissolved in organic or aqueous mixtures), it was not possible to fulfill the following analytical method criteria and thus the test item concentrations are given in the present report for information purposes only and should be regarded as trends. 

The test item decreasing over time in a natural river water at 12°C until its complete disappearance at day 30 was demonstrated. It should be noted that among the series of polysullphides targeted, the loss rates of the chromatographic peaks of dipentamethylenethiuram pentasulfide (S7), dipentamethylenethiuram hexasulfide (S8) and dipentamethylenethiuram heptasulfide (S9) were higher than the others peaks. Both abiotic control and river water conditions degradation patterns were similar, suggesting a chemical degradation rather than a biological degradation.

Additional information is available in the position paper attached to the IUCLID dossier. 

.