Bis(piperidinothiocarbonyl) hexasulphide

Hydrolysis

Link to relevant study record(s)

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.

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. 

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