Orthosulfamuron

Biodegradation in soil

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in soil: simulation testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2003

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 307 (Aerobic and Anaerobic Transformation in Soil)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test type:

field trial

Specific details on test material used for the study:

Test material:
[14C-U-phenyl]IR5878 Lot 209
Specific radioactivity: 441447 dpm/µg
198.850 µCi/mg
7.357 MBq/mg
Radiochemical purity: > 98% (by TLC)



[14C-5-pyrimidinyl]IR5878 Lot 208
Specific radioactivity: 267117 dpm/µg
120.323 µCi/mg
4.452 MBq/mg
Radiochemical purity: > 98% (by TLC)


Unlabelled IR5878
Batch number: 20698/27
Purity: 98.19% (by HPLC)

Radiolabelling:

yes

Oxygen conditions:

aerobic

Soil no.:

#1

Soil type:

sandy loam

% Org. C:

>= 0.72

pH:

>= 6.32

CEC:

>= 7.81 meq/100 g soil d.w.

Bulk density (g/cm³):

>= 1.11

Soil no.:

#2

Soil type:

silty clay loam

% Org. C:

>= 7.23

pH:

>= 6.24

CEC:

>= 34.26 meq/100 g soil d.w.

Bulk density (g/cm³):

>= 1.23

Soil No.:

#1

Duration:

>= 26 d

Soil No.:

#2

Duration:

>= 49 d

Soil No.:

#1

Initial conc.:

>= 75 g/ha d.w.

Soil No.:

#2

Initial conc.:

>= 75 g/ha d.w.

Parameter followed for biodegradation estimation:

radiochem. meas.

Soil No.:

#1

% Recovery:

99

Key result

Soil No.:

#1

DT50:

> 10 - < 25 d

Temp.:

18 - 22 °C

Transformation products:

yes

No.:

#1

No.:

#2

No.:

#3

No.:

#4

No.:

#5

Details on transformation products:

The main degradation pathway was represented by the hydrolytic cleavage of the sulfamoylurea linkage to give DBS acid and DOP urea as main degradation compounds.

A minor degradation pathway appeared to be the loss of methyl of the methoxy group on the pirimidinyl ring to yield O desmethyl IR5878 that degraded by hydrolytic cleavage to give DBS acid and O desmethyl DOP urea.

Findings

Phe-IR5878

The radioactivity in the surface water fast decreased from 48.08% and 31.58% AR at 0 day to 36.45% and 19.52% ARdays in M-1 bis and Fer systems, respectively; it kept constant till 14 and 17 days, then it was tending upward (36.72 % AR at 26 days and 37.53 % AR at 49 days, the last sampling time).

The radioactivity in soil quickly increased from 54.83% to 68.26% AR and from 72.60% to 83.30% AR in M-1 bis and Fer systems, respectively, then it slowly decreased.

The extractable radioactivity (from soil) ranged from 52.81% and 69.40% AR (0 day) to 43.25% and 47.26% AR (last sampling time) in M-1 bis and Fer systems, respectively.

The non-extractable radioactivity (bound residue) increased to 19.42% and 19.38% AR in M-1 bis and Fer, respectively.

The radioactivity in the¹⁴C-CO₂traps was always lower than the detection limit in both the systems except at the last sampling time in M-1 bis system where it reached values of 0.10% AR.

The Mass Balance was always higher than 99% AR and ranged from 99.49% to 104.61% AR.

 

Table 7.2-2     Phe-IR5878:¹⁴C-Mass balance (data are expressed as percentage of AR)

M-1 bis system
Time point (days)	Surface water	Soil			CO2	Total
		Extracts A+B+C	Bound residue	Total soil
0	48.08	52.81	2.02	54.83	nd	102.91
3	36.45	58.95	4.35	63.30	< dl	99.75
4	32.45	62.71	5.55	68.26	< dl	100.71
6	33.44	60.48	6.74	67.22	< dl	100.66
10	32.41	57.45	10.96	68.41	< dl	100.82
14	32.47	52.12	15.08	67.20	< dl	99.67
26	36.72	43.25	19.42	62.67	0.10	99.49
Fer system
Time point (days)	Surface water	Soil			CO2	Total
		Extracts A+B+C	Bound residue	Total soil
0	31.58	69.40	3.20	72.60	nd	104.18
3	19.52	72.64	10.66	83.30	< dl	102.82
4	21.41	71.05	10.35	81.40	< dl	102.81
6	18.63	71.91	12.17	84.08	< dl	102.71
10	19.72	64.03	18.09	82.12	< dl	101.84
17	22.73	63.78	18.10	81.88	< dl	104.61
26	28.48	57.09	18.80	75.89	< dl	104.37
49	37.53	47.26	19.38	66.64	< dl	104.17
nd = not determined dl =%

 

Eight degradation compounds were found in the surface water and in the soil extracts.

The main degradation compounds S1 and S9, which reached amounts higher than 10% AR, were identified as (2-dimethylcarbamoylphenyl) sulfamic acid (named DBS acid) and as 1-(4-hydroxy-6-methoxypyrimidin-2-yl)-3-[2-(dimethylcarbamoyl) phenyl sulfamoyl] urea (named O-desmethyl IR5878).

The other degradation compounds S2, S4, S5, S7, S8, and S16 never reached amounts higher than 10%. However S2 was identified as 2-[(aminosulfonyl)amino]-N,N-dimethyl benzamide (named DBS amide).

 

Table 7.2-3     Phe-IR5878: Radioactivity distribution (data are expressed as percentage of IR5878 equivalents to AR)

M-1 bis system
Time point (days)	Surface water			Soil			Whole system
	S1	S3 (IR5878)	S9	S1	S3 (IR5878)	S9	S1	S3 (IR5878)	S9
0	1.96	41.97	0.94	0.97	49.85	0.30	2.93	91.82	1.24
3	10.10	22.00	1.37	9.47	37.35	6.54	19.57	59.35	7.91
4	10.27	17.23	1.92	11.72	37.35	9.50	21.99	54.58	11.41
6	10.74	17.73	3.13	12.65	30.50	12.98	23.39	48.22	16.11
10	12.74	12.25	5.47	15.94	20.24	15.51	28.68	32.49	20.98
14	14.26	8.79	6.96	16.38	15.67	14.68	30.64	24.45	21.63
26	21.23	3.58	7.91	17.65	8.26	7.90	38.87	11.83	15.80
Fer system
Time point (days)	Surface water			Soil			Whole system
	S1	S3 (IR5878)	S9	S1	S3 (IR5878)	S9	S1	S3 (IR5878)	S9
0	2.15	26.21	0.91	2.52	64.43	nd	4.66	90.64	0.91
3	5.30	12.13	0.61	10.32	55.44	1.12	15.61	67.57	1.73
4	7.31	11.63	0.66	12.79	54.14	0.79	20.09	65.76	1.44
6	7.56	9.58	0.52	13.93	53.32	0.95	21.49	62.90	1.47
10	10.08	7.80	0.61	16.63	42.21	1.22	26.71	50.00	1.83
17	15.94	4.85	0.71	20.94	37.42	1.57	36.87	42.27	2.28
26	21.69	3.30	1.16	23.01	25.14	2.10	44.69	28.44	3.26
49	30.65	2.21	1.48	22.32	16.70	2.26	52.96	18.91	3.74
nd = not determined

 

Pyr-IR5878

The radioactivity in the surface water quickly decreased during the first three days from 44.15% to 26.22% applied radioactivity (AR) and from 33.72% to 11.22% AR in M-1 bis and Fer systems, respectively; then it slowly decreased till 16.91% and 3.80% AR.

The radioactivity in soil quickly increased during the first three days from 57.73% to 75.21% AR and from 70.21% to 93.17% AR in M-1 bis and Fer systems, respectively, then it very slowly increased till 82.90% and till 102.96% AR.

The extractable radioactivity (from soil) ranged from 49.79% to 69.15% AR in M-1 bis system and from 59.68% to 80.19% AR in Fer system.

The non-extractable radioactivity increased to 33.11% and 43.28% AR in M-1 bis and Fer systems, respectively.

The fractionation of organic matter showed that, in samples incubated 14 and 26 days of M-1 bis system, most of the radioactivity was found in fulvic acid fraction (12.09% and 17.99% AR), while in samples incubated from 10 to 49 days of Fer system most of the radioactivity was in humin fraction (it increased from 16.77% to 25.81% AR).

The radioactivity in the¹⁴C-CO₂traps was always lower than the detection limit in both the systems except at the last sampling time in M-1 bis system where it reached values of 0.16% AR.

The Mass Balance was always higher than 99% AR and ranged from 99.97% to 107.03% AR.

 

Table 7.2-4     Pyr-IR5878:¹⁴C-Mass balance (data are expressed as percentage of AR)

M-1 bis system
Time point (days)	Surface water	Soil			CO2	Total
		Extracts A+B+C	Bound residue	Total soil
0	44.15	55.65	2.08	57.73	nd	101.88
3	26.22	69.15	6.06	75.21	< dl	101.43
4	26.34	68.68	6.63	75.31	< dl	101.65
6	24.76	65.56	10.52	76.08	< dl	100.84
10	26.65	59.02	15.06	74.08	< dl	100.73
14	21.55	56.62	21.80	78.42	< dl	99.97
26	16.91	49.79	33.11	82.90	0.16	99.97
Fer system
Time point (days)	Surface water	Soil			CO2	Total
		Extracts A+B+C	Bound residue	Total soil
0	33.72	66.62	3.50	70.12	nd	103.84
3	11.22	80.19	12.98	93.17	< dl	104.39
4	13.64	77.39	13.94	91.33	< dl	104.97
6	11.12	77.61	17.42	95.03	< dl	106.15
10	9.27	70.17	25.97	96.14	< dl	105.41
17	6.99	70.79	28.61	99.40	< dl	106.39
26	6.30	67.96	32.77	100.73	< dl	107.03
49	3.80	59.68	43.28	102.96	< dl	106.76
nd = not determined dl =%

 

Six degradation compounds were found in the surface water and in the soil extracts.

The main degradation compounds S9 and S12, which reached amounts higher than 10% AR, were identified as 1-(4-hydroxy-6-methoxypyrimidin-2-yl)-3-[2-(dimethylcarbamoyl)phenyl sulfamoyl] urea (named O-desmethyl IR5878) and as N-(4,6-dimethoxypyrimidin-2-yl) urea (named DOP urea).

The other degradation compounds S11, S13, S15 and S16 never reached amounts higher than 10%. However S15 was identified as (4-hydroxy-6-methoxypyrimidin-2-yl) urea (named O-desmethyl DOP urea).

 

Table 7.2-5     Pyr-IR5878: Radioactivity distribution (data are expressed as percentage of IR5878 equivalents to AR)

M-1 bis system
Time point (days)	Surface water			Soil			Whole system
	S3 (IR5878)	S9	S12	S3 (IR5878)	S9	S12	S3 (IR5878)	S9	S12
0	39.68	0.45	1.27	50.98	nd	3.54	90.65	0.45	4.80
3	16.44	0.95	7.46	38.30	6.92	20.02	54.74	7.87	27.47
4	15.71	1.38	7.48	35.82	8.02	22.13	51.53	9.40	29.61
6	16.55	2.57	4.94	28.74	11.69	21.89	45.29	14.26	26.83
10	12.96	4.48	8.55	19.10	10.80	24.47	32.05	15.28	33.02
14	8.50	6.05	6.07	15.26	11.26	24.82	23.76	17.30	30.89
26	3.94	6.95	4.57	8.95	7.83	21.14	12.89	14.78	25.71
Fer system
Time point (days)	Surface water			Soil			Whole system
	S3 (IR5878)	S9	S12	S3 (IR5878)	S9	S12	S3 (IR5878)	S9	S12
0	31.10	0.42	0.52	60.85	nd	4.42	91.94	0.42	4.94
3	8.04	0.30	2.20	55.97	0.73	20.05	64.01	1.03	22.25
4	11.54	0.25	1.45	51.95	0.48	23.00	63.49	0.73	24.45
6	9.40	0.32	1.29	51.39	0.74	22.73	60.78	1.05	24.02
10	7.14	0.31	1.60	37.83	0.82	29.17	44.97	1.13	30.77
17	4.79	0.44	1.44	33.08	1.11	33.94	37.87	1.55	35.38
26	3.10	0.83	2.02	22.44	2.05	38.95	25.54	2.88	40.97
49	1.28	0.80	1.37	12.73	1.88	38.45	14.00	2.68	39.82
nd = not determined

 

Conclusions:

In conclusion IR5878 degraded in both paddy-field soils, faster in M-1 bis than in Fer system:
 after 26 days in M-1 bis system it accounted for 11.83 % and 12.89 % AR (Phe-IR5878 and Pyr-IR5878, respectively);
 after 49 days in Fer system it accounted for 18.17 % and 14.00 % AR.

The DT50labvalues were between 8 and 16 days in surface water, between 10 and 25 days in soil and between 9 and 23 days in whole system. The DT90labvalues were between 27 and 52 days in surface water, between 33 and 83 days in soil and between 30 and 75 days in whole system.

Executive summary:

The degradation of [¹⁴C-U-phenyl]IR5878 and of [¹⁴C-5-pyrimidinyl]IR5878 in the dark was studied in two paddy-field soils: sandy loam (M-1 bis system) and silty clay loam (Fer system).

In conclusion IR5878 degraded in both paddy-field soils, faster in M-1 bis than in Fer system: after 26 days in M-1 bis system it accounted for 11.83 % and 12.89 % AR (Phe-IR5878 and Pyr-IR5878, respectively); after 49 days in Fer system it accounted for% and% AR. The DT_50labvalues were between 8 and 16 days in surface water, between 10 and 25 days in soil and between 9 and 23 days in whole system. The DT_90labvalues were between 27 and 52 days in surface water, between 33 and 83 days in soil and between 30 and 75 days in whole system.

Description of key information

The degradation of [¹⁴C-U-phenyl]IR5878 and of [¹⁴C-5-pyrimidinyl]IR5878 in the dark was studied in two paddy-field soils: sandy loam (M-1 bis system) and silty clay loam (Fer system).

In conclusion IR5878 degraded in both paddy-field soils, faster in M-1 bis than in Fer system: after 26 days in M-1 bis system it accounted for 11.83 % and 12.89 % AR (Phe-IR5878 and Pyr-IR5878, respectively); after 49 days in Fer system it accounted for% and% AR. The DT_50labvalues were between 8 and 16 days in surface water, between 10 and 25 days in soil and between 9 and 23 days in whole system. The DT_90labvalues were between 27 and 52 days in surface water, between 33 and 83 days in soil and between 30 and 75 days in whole system.

IR5878 degradation was also studied under sunlight and was found to quickly degrade according to a first order kinetics. It accounted for

       0.75% in Phe-IR5878 samples after 30 days;

       0.40% in Pyr-IR5878 samples after 21 days.

The DT50 was 0.95-0.96 days for surface water, 1.94-3.23 days for soil and 1.53-2.43 for the whole system.

The sunlight degradation rate of IR5878 was ten times higher than in the dark. Outdoor conditions appeared to largely affect the degradation of the both the test item and its degradation products.

Key value for chemical safety assessment

Half-life in soil:

25 d

at the temperature of:

20 °C