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Environmental fate & pathways

Biodegradation in soil

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Reference
Endpoint:
biodegradation in soil: simulation testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2008 and 2010
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
according to
Guideline:
OECD Guideline 307 (Aerobic and Anaerobic Transformation in Soil)
Version / remarks:
2002
Principles of method if other than guideline:
Two experiments were performed:
1. 2008 with Soil 1, 15 days
2. 2010 with Soil 1 and Soil 2, 28 days
GLP compliance:
not specified
Remarks:
Study was performed for inclusion of substance 2-(3,4-dimethyl-pyrazol-1-yl)-succinic acid in Regulation (EC) 2003/2003, Table F.2-Nitrification Inhibitors. It was intentionally not performed to be used for registration under Regulation (EC) No 1907/2006.
Test type:
laboratory
Radiolabelling:
no
Oxygen conditions:
aerobic
Soil classification:
other: Food and Agriculture Organization of the United Nations (FAO)
Soil no.:
#1
Soil type:
sandy loam
% Clay:
4
% Silt:
23
% Sand:
73
% Org. C:
1.37
pH:
6.8
Soil no.:
#2
Soil type:
sandy loam
% Clay:
3
% Silt:
22
% Sand:
75
% Org. C:
0.99
pH:
6.1
Details on soil characteristics:
SOIL COLLECTION AND STORAGE
- Geographic location: Soil 1: Limburgerhof, Germany; Soil 2: Kaldenkirchen, Germany
- Collection procedures: About 3 weeks before the beginning of the tests Soil 2 was taken out of the uppermost layer of soil from lysimeters filled at the Jülich research centre and provided to the test facility.

Soil No.:
#1
Duration:
15 d
Soil No.:
#1
Duration:
28 d
Soil No.:
#2
Duration:
28 d
Soil No.:
#1
Initial conc.:
33.1 other: µg test substance in 50 g soil
Based on:
test mat.
Soil No.:
#2
Initial conc.:
33.1 other: µg test substance in 50 g soil
Based on:
test mat.
Parameter followed for biodegradation estimation:
test mat. analysis
Soil No.:
#1
Temp.:
20 °C
Humidity:
50%
Soil No.:
#1
% Degr.:
100
Parameter:
test mat. analysis
Sampling time:
15 d
Soil No.:
#1
% Degr.:
99.9
Parameter:
test mat. analysis
Sampling time:
28 d
Soil No.:
#2
% Degr.:
100
Parameter:
test mat. analysis
Sampling time:
28 d
Soil No.:
#1
DT50:
3.3 d
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: SFO model
Soil No.:
#1
DT50:
2.9 d
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: SFO model
Soil No.:
#2
DT50:
1.5 d
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: SFO model
Transformation products:
yes
No.:
#1
Details on transformation products:
- Formation and decline of each transformation product during test:
DMP formation:
Soil 1
30% of applied 1A after 15 days (2008 experiment)
99.4% of applied 1A after 28 days (2010 experiment)
Soil 2
93.4% of applied 1A after 28 days (2010 experiment)
Details on results:
Normalised half-lives for DMP(P):
Soil #1, 15 d sampling: 7.6 d (DMP(P) application)
Soil #1, 28 d sampling: 7.2 d (DMP(P) application)
Soil #2, 28 d sampling: 3.8 d (DMP(P) application)
Soil #1, 15 d sampling: T-test for k-rate not significant; DegT50 was excluded from obtained modelling endpoints (pathway fit)
Soil #1, 28 d sampling: 8.1 d (pathway fit)
Soil #2, 28 d sampling: 8.9 d (pathway fit)

Table: Detection of 1A in % after application of 1A or DMP(P) to Soil 1 following extraction with K2SO4 solution (mean of three replicates) during the experiment of 2008.

 

Application of DMP(P)

Application of 1A

Incubation time (days)

mean

SD

mean

SD

0

0.0

0.0

n.a.

n.a.

1

0.0

0.0

92.0

0.7

2

0.0

0.0

83.1

2.4

5

0.0

0.0

53.9

7.1

7

0.0

0.0

33.0

1.9

9

0.0

0.0

13.2

2.8

12

0.0

0.0

2.1

0.9

15

0.0

0.0

0.0

0.0

Table: Detection of DMP in % after application of DMP(P) or 1A to Soil 1 following extraction with 1% K2SO4 solution (mean of three replicates) during the experiment of 2008.

 

Application of DMP(P)

Application of 1A

Incubation time (days)

mean

SD

mean

SD

0

86.0

2.7

0.8

0.0

1

75.8

3.1

4.5

0.3

2

69.8

2.2

9.8

0.5

5

53.1

2.1

22.0

1.5

7

46.9

1.3

28.0

0.7

9

42.2

0.8

35.1

0.5

12

37.8

0.4

38.4

1.8

15

31.1

1.1

31.7

0.6

 

Table: Detection of 1A in % after application of DMP(P) or 1A to Soil 1 following extraction with 1% K2SO4 solution (mean of three replicates) during the 2010 experiment.

 

Application of DMP(P)

Application of 1A

Incubation time (days)

mean

SD

mean

SD

0

0

0

106.2

3.6

2

0

0

85.5

0.2

5

0

0

54.3

4.8

9

0

0

9.3

1.3

14

0

0

0.5

0.0

21

0

0

0.3

0.2

28

0

0

0.2

0.1

 

Table: Detection of 1A in % after application of DMP(P) or 1A to Soil 2 following extraction with 1% K2SO4 solution (mean of three replicates) during the 2010 experiment.

 

Application of DMP(P)

Application of 1A

Incubation time (days)

mean

SD

mean

SD

0

0

0

94.6

1.1

2

0

0

41.8

2.3

5

0

0

19.5

4.1

9

0

0

1.8

0.6

14

0

0

0.2

0.2

21

0

0

0.1

0.0

28

0

0

0.1

0.1

 

Table: Detection of DMP(P) in % after application of DMP(P) or 1A to Soil 1 following extraction with 1% K2SO4 solution (mean of three replicates) during the 2010 experiment.

 

Application of DMP(P)

Application of 1A

Incubation time (days)

mean

SD

mean

SD

0

sample lost

n.a.

0.7

0.2

2

37.6

2.5

0.6

0.2

5

29.3

1.2

13.4

4.6

9

22.4

1.3

33.1

1.4

14

15.7

0.6

21.4

1.9

21

7.1

1.6

8.9

1.9

28

6.3

5.2

5.9

4.6

 

Table: Detection of DMP(P) in % after application of DMP(P) or 1A to Soil 2 following extraction with 1% K2SO4 solution (mean of three replicates) during the 2010 experiment.

 

Application of DMP(P)

Application of 1A

Incubation time (days)

mean

SD

mean

SD

0

88.7

3.2

0.3

0.2

2

51.1

4.5

13.2

2.2

5

37.4

3.4

18.5

2.9

9

24.6

0.9

23.9

0.6

14

16.8

0.5

17.5

1.2

21

4.3

1.4

5.5

0.8

28

7.6

1.1

7.4

0.2

Description of key information

100% transformation in 28 d (OECD 307)

Half-life of Reaction mass of 2-(3,4-dimethyl-1H-pyrazol-1-yl)succinic acid and 2-(4,5-dimethyl-1H-pyrazol-1-yl)succinic acid: 1.5 - 3.3 days

Key value for chemical safety assessment

Additional information

Data from two independent microcosm studies are available on the biodegradation of Reaction mass of 2-(3,4-dimethyl-1H-pyrazol-1-yl)succinic acid and 2-(4,5-dimethyl-1H-pyrazol-1-yl)succinic acid and its metabolite 3,4- dimethylpyrazole (DMP) in soil. The studies were conducted under aerobic conditions at 20 °C and ca. 50% of maximum water holding capacity (MWHC), following the OECD Guideline 307 (Wissemeier, 2012). The first degradation study was carried out in 2008 with Limburgerhof soil, Germany (15 days) and the second in 2010 with soils from Limburgerhof and Kaldenkirchen, Germany (28 days). In total 6 independent data sets were available. In 3 of these data sets Reaction mass of 2-(3,4-dimethyl-1H-pyrazol-1-yl)succinic acid and 2-(4,5-dimethyl-1H-pyrazol-1-yl)succinic acid was applied as test substance, while in 3 further data sets DMP was applied as formulated DMP(P) to the test soils. For each individual test 50 g soil was weighed and dosed with either 33.1 μg Reaction mass of 2-(3,4-dimethyl-1H-pyrazol-1-yl)succinic acid and 2-(4,5-dimethyl-1H-pyrazol-1-yl)succinic acid or DMP(P). For the test in 2008, samples were taken after 0, 1, 2, 5, 7, 9, 12 and 15 days and for the soils tested in 2010 sampling after 0, 2, 5, 9, 14, 21 and 28 days was considered. Extraction data from 2008 demonstrated a tendency towards higher extractability when 1% K2SO4 solution is used as extraction agent compared to 0.01 mol/L CaCl2. Therefore, samples in 2010 were only extracted with K2SO4. Samples were stored frozen (-18 to -20°C) until analysis (1 to 5 weeks later). Subsequent measurements of soil extracts were carried out using LC-MS/MS. Fast transformation of Reaction mass of 2-(3,4-dimethyl-1H-pyrazol-1-yl)succinic acid and 2-(4,5-dimethyl-1H-pyrazol-1-yl)succinic acid to DMP was observed. In a separate kinetics evaluation conducted with data from this study, normalised half-lives of 1.5 - 3.3 days and formation fractions of 0.32 - 0.45 were determined for the transfomation of the test substance to DMP. The normalised half-life of DMP in soil, tested in parallel, was determined to be 3.8 - 8.9 days (Kahl, 2012).