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Administrative data

Endpoint:
biodegradation in soil: simulation testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Start: 23 January 2014, Completed: 27 May 2014
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study performed under GLP.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2014
Report date:
2014

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 307 (Aerobic and Anaerobic Transformation in Soil)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Test type:
laboratory

Test material

Constituent 1
Chemical structure
Reference substance name:
-
EC Number:
425-950-7
EC Name:
-
Cas Number:
187393-00-6
Molecular formula:
C38-H49-N3-O5
IUPAC Name:
5-[(2-ethylhexyl)oxy]-2-(4-{4-[(2-ethylhexyl)oxy]-2-hydroxyphenyl}-6-(4-methoxyphenyl)-1,3,5-triazin-2-yl)phenol
Details on test material:
Molecular formula: C38H49N3O5
Molecular weight: 627.8
CAS Number: 187393-00-6
Description: Pale yellow powder
Batch: 0M000254477
Purity/Composition: 98%
Test substance storage: At room temperature in the dark
Stable under storage conditions until 28 October 2015 (retest date)

Radiolabelling:
no

Study design

Oxygen conditions:
aerobic
Soil propertiesopen allclose all
Soil no.:
#1
Soil type:
loamy sand
% Clay:
8.2
% Silt:
15.3
% Sand:
76.5
% Org. C:
1.74
pH:
5.5
Soil no.:
#2
Soil type:
sandy loam
% Clay:
8.7
% Silt:
28.2
% Sand:
63.1
% Org. C:
1
pH:
6.8
Soil no.:
#3
Soil type:
clay
% Clay:
40.7
% Silt:
34.5
% Sand:
24.8
% Org. C:
1.66
pH:
7.1
Details on soil characteristics:
Soil characteristics were determined by CEM Analytical Services (CEMAS), Berkshire, UK as a separate GLP study.
Upon receipt at WIL Research Europe, the sieved soils were stored at 4°C. Prior to start of the equilibration period, the soil moisture content of a 50 g sample of each soil was determined by oven drying overnight at approximately 108°C. The soils were brought to 40% of their maximum water holding capacity by adding Milli-Q water. Portions of 50-g oven dry weight equivalent soil were weighed out in 1L cylindrical, brown metabolism flasks. Per soil 20 flasks were prepared. The soils were maintained at 40% of their maximum water holding capacity by adding Milli-Q water as necessary (checked at least once every two weeks). The equilibration period started on 24 January 2014 for all soils. The soils were equilibrated in the dark at 20°C ± 2°C for a period of 3 days. At the end of the equilibration period, the soil of four flasks for each soil system were combined and shipped to Cranfield University, UK for the determination of the microbial biomass using the fumigation-extraction method (excluded from GLP).
Duration of test (contact time)open allclose all
Soil No.:
#1
Duration:
120 d
Soil No.:
#2
Duration:
120 d
Soil No.:
#3
Duration:
120 d
Initial test substance concentrationopen allclose all
Soil No.:
#1
Initial conc.:
2 mg/kg soil d.w.
Based on:
test mat.
Soil No.:
#2
Initial conc.:
2 mg/kg soil d.w.
Based on:
test mat.
Soil No.:
#3
Initial conc.:
2 mg/kg soil d.w.
Based on:
test mat.
Parameter followed for biodegradation estimation:
test mat. analysis
Experimental conditionsopen allclose all
Soil No.:
#1
Temp.:
17.9°C - 22.5°C
Humidity:
33.7%
Microbial biomass:
212 μg C/g dry sample
Soil No.:
#2
Temp.:
17.9°C - 22.5°C
Humidity:
31.7%
Microbial biomass:
85.1 µg C/g dry sample
Soil No.:
#3
Temp.:
17.9°C - 22.5°C
Humidity:
31.8%
Microbial biomass:
321 µg C/g dry sample

Results and discussion

% Degradationopen allclose all
Soil No.:
#1
% Degr.:
ca. 0
Parameter:
test mat. analysis
Sampling time:
120 d
Soil No.:
#2
% Degr.:
ca. 0
Parameter:
test mat. analysis
Sampling time:
120 d
Soil No.:
#3
% Degr.:
ca. 0
Parameter:
test mat. analysis
Sampling time:
120 d
Half-life / dissipation time of parent compoundopen allclose all
Soil No.:
#1
DT50:
> 1 000 d
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: DT90 >1000 d
Soil No.:
#2
DT50:
> 1 000 d
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: DT90 >1000 d
Soil No.:
#3
DT50:
> 1 000 d
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: DT90 >1000 d
Transformation products:
no
Evaporation of parent compound:
no
Details on results:
During incubation, Escalol S did not degrade in any of the three soils. After 120 days of incubation the concentration of Escalol S in soil was still 2.0 – 2.2 mg/kg (102-112% of nominal concentration).

Any other information on results incl. tables

Table 1: Relative to nominal concentrations of the test substance in the soils (%)

Time [days]

Speyer 2.2

Speyer 2.3

Speyer 6S

0

118

99

122

3

99

109

105

7

107

109

107

14

77

92

94

28

79

94

99

70

91

102

115

120

103

102

112

 

Applicant's summary and conclusion

Conclusions:
The half- life (DT50) of Escalol S was more than 1000 days in Speyer 2.2 soil, Speyer 2.3 and Speyer 6S, as described by single first order kinetics.
Executive summary:

The degradation rate of Escalol S was investigated in three soils for a period of 120 days according to the OECD 307 guideline. The following soils were used: Speyer 2.2 (loamy sand), Speyer 2.3 (sandy loam) and Speyer 6S (clay).

 

The soil was brought to approximately 40% of its water holding capacity by adding Milli-Q water. Aliquots of soil (50 g dry weight) were treated with the test substance at a nominal concentration of 2 mg/kg dry soil. The soil samples were incubated at 20 ± 2°C in the dark.

 

Single samples of each soil were taken after 0, 3, 7, 14, 28, 70 and 120 days of incubation. Soil samples were extracted with50 mL acetonitrile at 300 rpm for 10 minutes. 50 mL of dichloromethane was added to these suspensions and the samples were shaken again for 10 minutes at 300 rpm. The extracts were analysed by UPLC-MS/MS.

 

After 120 days of incubation, 102-112% of nominally applied Escalol S was recovered.

The degradation rate of Escalol S was calculated according to the FOCUS Guidance Document [1]. The half-life (DT50) and DT90values are shown in the table below:

Soil

DT50

[days]

DT90

[days]

χ2(err)

Kinetic model

Speyer 2.2

>1000

>1000

11.4

SFO

Speyer 2.3

>1000

>1000

4.8

SFO

Speyer 6S

>1000

>1000

6.5

SFO