1-[2-(2-chloroethoxy)phenylsulfonyl]-3-(4-methoxy-6-methyl-1,3,5-triazin-2-yl)urea;triasulfuron (ISO)

Biodegradation in soil

Description of key information

Nine biodegradation in soil studies are available and included as supporting information. More details are provided in the additional information.

Additional information

Studies required in Annex VII and some other studies required for higher tonnage are available. All the studies available have been included in the dossier and some of them are considered in the PBT assessment. Therefore, all studies are summarized below. Seven aerobic studies and two aerobic/anaerobic studies are available for this endpoint. Five of them followed standard test guidelines and four of them complied with GLP. Calculation of degradation half-lives according to a standardized methodology across three studies (Hurst 2013 and Hurst 2012) is presented in Greener’s report (2012). The test conditions and key effect values of all studies were summarised in Table 1- Table 2 below.

Table 1. Test conditions and key effect values of aerobic studies that followed standard test conditions (i.e. meet OECD, SETAC, OPPTS or JMAFF guideline requirements) and were used in a weight of evidence approach for the CSA.

USDA / Name / Origin	OC [%] / pH (water)	T. [°C] / Moisture / Appl. Rate	DT50 [d] - Kinetic model in original report	DT50 [d] - Kinetic model recalculated	Author / Year
Sandy clay loam, 18 Acres, UK	2.6 / 6.5	20 / pF 2 / 0.08 mg/kg	26.9 – SFO	67.4* – DFOP slow phase	Hurst, 2013; Greener, 2012
Sandy clay loam, 18 Acres, UK	2.6 / 6.5	20 / pF 2 / 0.08 mg/kg	32.0 - SFO	118* – DFOP slow phase	Hurst, 2013; Greener, 2012
Loam, Gartenacker, CH	1.9 / 8.5	20 / pF 2 / 0.04 mg/kg	20.7 - SFO	20.7* – SFO	Hurst, 2012; Greener, 2012
Sandy clay loam, 18 Acres, UK	2.2 / 6.7	20 / pF 2 / 0.04 mg/kg	33.9 – SFO	84.7* – DFOP slow phase	Hurst, 2012; Greener, 2012
Silt loam, Krone, CH	1.2 / 6.9	20 / pF 2 / 0.04 mg/kg	43.1 – SFO	80.2* – DFOP slow phase	Hurst, 2012; Greener, 2012
Sandy clay loam, North Dakota, USA	2.7 / 7.7	20 / pF 2 / 0.04 mg/kg	60.6 - SFO	60.6* – SFO	Hurst, 2012; Greener, 2012
			Geomean / Median	54.5

* Value used for determination of the geomean; geomean for 18 Acres soil calculated first (87.7 d, n=3)

Table 2. Test conditions and key effect values of studies that were performed under anaerobic conditions or without following standard test conditions (i.e. meet OECD, SETAC, OPPTS or JMAFF guideline requirements)*

USDA / Name / Origin	OC [%] / pH (water)	T. [°C] / Moisture / Appl. Rate	DT50 [d] - Kinetic model in original report	Aerobic/anaerobic	Author / Year
Sandy Loam, Fayette, Kentucky, USA	1.8 / 7.5	20 / 75% FC / 4.2 mg/kg	111.8 (linear SFO)	anaerobic	Olson, 1989
Silt loam, Strassenacker, Les Barges, CH	1.4 / 7.6	25 / 75% FC / 1.1 mg/kg	325.5 (SFO)	Aerobic (Sterile)	Plücken, 1985a
Silt loam, Strassenacker, Les Barges, CH	1.4 / 7.6	25 / 75% FC / 1.1 mg/kg	66.5 - SFO	Aerobic (Non -sterile)	Plücken, 1985a
Silt loam, Strassenacker, Les Barges, CH	1.4 / 7.6	25 / 75% FC / 0.94 mg/kg	105 – SFO	Aerobic (Non -sterile)	Plücken, 1985b
Silt loam, Strassenacker, Les Barges, CH	1.45 / 7.5	25 / 75% FC / 1.01mg/kg	52.8 – SFO	Aerobic (Non -sterile)	Plücken, 1989
Silt loam, Strassenacker, Les Barges, CH	1.45 / 7.5	15 / 75% FC / 1.01mg/kg	121.5 - SFO	Aerobic (Non -sterile)	Plücken, 1989
Mosimann, CH	1.6 / 7.2	25 / 40% MWC / 1.06 mg/kg	70.9 – SFO	Aerobic (Non -sterile)	Plücken, 1986a
Pappelacker, CH	2.1 / 7.1	25 / 40% MWC / 1.06 mg/kg	73.5 – SFO	Aerobic (Non -sterile)	Plücken, 1986a
Standard 2.2, Neuhofen, CH	0.95 / 5.6	25 / 40% MWC / 1.07 mg/kg	44.9 – SFO	Aerobic (Non -sterile)	Plücken, 1986b
Standard 2.3, Hatzenbuehl, CH	1.45 / 7.5	25 / 40% MWC / 1.07 mg/kg	38.6 – SFO	Aerobic (Non -sterile)	Plücken, 1986b

* Example of non-standard test conditions: Sterile soil, low/high incubation temperatures, low/high moisture content, exaggerated application rate etc.

Field studies

A large number of field studies were conducted with the test material. The studies are not summarized as an endpoint study entry but are briefly discussed here. The test material was tested for different applications in different crops and bare grounds with a rate ranging between 10 - 2240 g/ha. The DT50 reported in the original reports were between 3 - 91 days. The DT50 as recalculated in SFO and DFOP models were between 2 - 65.4 days. The geometric mean DT50 (n=7) for the substance degradation in soil under representative field conditions was calculated to be 16.5 days (Resseier 1992a, Resseier 1992b, Resseier 1992c, Resseier 1992d, Tournayre 1988, Egli 1989a, Egli 1989b, Hardy 2011 and Hardy 2016).