3-methylpyrazole

Biodegradation in soil

Administrative data

Endpoint:

biodegradation in soil: simulation testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2021-08-11 - 2021-12-06

Reliability:

1 (reliable without restriction)

Data source

Reference

Title:

Unnamed

Year:

2021

Report date:

2021

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

Test material information

Constituent 1

Reference substance name:

3-methylpyrazole

EC Number:

215-925-7

EC Name:

3-methylpyrazole

Cas Number:

1453-58-3

Molecular formula:

C4H6N2

IUPAC Name:

3-methyl-1H-pyrazole

Test material form:

liquid

Radiolabelling:

no

Study design

Oxygen conditions:

aerobic

Soil classification:

DIN 19863 (Deutsche Industrie-Norm)

Soil properties

Soil properties 1

Soil no.:

#3

Soil type:

other: silty sand

% Org. C:

0.66

pH:

6.2

CEC:

6

% Moisture content:

45

Soil properties 2

Soil no.:

#2

Soil type:

loamy sand

% Org. C:

1.77

pH:

5.6

CEC:

8.5

% Moisture content:

45

Soil properties 3

Soil no.:

#1

Soil type:

sand

% Org. C:

0.61

pH:

4.7

CEC:

3.1

% Moisture content:

45

Details on soil characteristics:

see below

Duration of test (contact time)

Duration of test (contact time) 1

Soil No.:

#3

Duration:

18 d

Duration of test (contact time) 2

Soil No.:

#2

Duration:

240 h

Duration of test (contact time) 3

Soil No.:

#1

Duration:

14 d

Initial test substance concentration

Initial test substance concentration 1

Soil No.:

#3

Initial conc.:

0.3 mg/kg soil d.w.

Based on:

test mat.

Initial test substance concentration 2

Soil No.:

#2

Initial conc.:

0.3 mg/kg soil d.w.

Based on:

test mat.

Initial test substance concentration 3

Soil No.:

#1

Initial conc.:

0.3 mg/kg soil d.w.

Based on:

test mat.

Parameter followed for biodegradation estimation:

test mat. analysis

Experimental conditions

Experimental conditions 1

Soil No.:

#3

Temp.:

20°C

Humidity:

45 % MWHC

Microbial biomass:

11.2 mg C/100 g

Experimental conditions 2

Soil No.:

#2

Temp.:

20°C

Humidity:

45 % MWHC

Microbial biomass:

37.4 mg C/100 g

Experimental conditions 3

Soil No.:

#1

Temp.:

20 °C

Humidity:

45 % MWHC

Microbial biomass:

15.1 mg C/100 g

Details on experimental conditions:

The microbial biomass of the soils at start and end of the experiment was determined by for the batches of LUFA 2.1, LUFA 2.2 and LUFA 2.3 soils used in this study. The microbial biomass was determined at LUFA Speyer, Obere Langgasse 40, 67346 Speyer. The biomass determination was done in a separate GLP study (Study Number at LUFA Speyer: BP 06/21, see Reference (3)).
The experimental soils LUFA 2.1, LUFA 2.2 and LUFA 2.3 were stored at 2-8°C for 24 days, until the start of the pre-incubation period (27 August 2021) for the definitive test. The quality of the soils was proved by the determination of their microbial biomass (see Appendix 2: soil certificates).
The soils were moistened to 45 % maximum water holding capacity (MWHC) prior to the start of the pre-incubation period (17 September 2021).
The soils were maintained at this moisture level (± 1 % based on dry weight) throughout the study and maintained at a constant temperature of 20 ± 2 °C in the dark.
The application of the test item (3-Methylpyrazole, purity of 98.8 %) was made to the soil surface by solvent application on 20 September 2021. The treated soils were thoroughly mixed, by manual shaking, to incorporate the test item into soil.
Amounts of conditioned soil at 45 % MWHC, equivalent to 100 g dry weight were bottled into 1000 mL all glass metabolism flasks (conical shoulder bottles of 10 cm inner diameter) and maintained under a dynamic atmosphere of air by passing a continous airflow through the system in order to keep aerobic conditions, in the dark, at 20 ± 2 °C (see experimental section 8.3). Air entering the system was passed through a washing bottle to reduce the water loss of soil. The metabolism flasks were connected via tubing and good humidification maintained (clearly visible bubbles). A flow meter was used to measure the air flow.
Each test vessel was allocated a number that was used internally during the experimental phase.

Results and discussion

Half-life / dissipation time of parent compound

Half-life / dissipation time of parent compound 1

Key result

Soil No.:

#3

DT50:

3.5 d

Type:

(pseudo-)first order (= half-life)

Temp.:

20 °C

Half-life / dissipation time of parent compound 2

Key result

Soil No.:

#2

DT50:

1.7 d

Type:

(pseudo-)first order (= half-life)

Temp.:

20 °C

Half-life / dissipation time of parent compound 3

Key result

Soil No.:

#1

DT50:

2.9 d

Type:

(pseudo-)first order (= half-life)

Temp.:

20 °C

Transformation products:

not measured

Any other information on results incl. tables

 

Results of Definitive Test of 3-Methylpyrazole for LUFA 2.1

LUFA 2.1
mass transition:	3-Methylpyrazole	3-Methylpyrazole	3-Methylpyrazole
m/z 83 > m/z 56	found	found	found
days	[mg/kg dry weight]	[%]	mean [%]
0	0.270	89.6	89.7
	0.271	89.7
1	0.226	74.9	75.5
	0.230	76.2
2	0.201	66.6	66.1
	0.198	65.6
3	0.178	59.1	60.5
	0.187	62.0
5	0.068	22.6	20.4
	0.055	18.1
7	0.020	6.6	6.4
	0.018	6.1
10	0.0086	2.9	2.7
	0.0075	2.5
14	0.0040	1.3	1.4
	0.0042	1.4

Results of Definitive Test of 3-Methylpyrazole for LUFA 2.2

LUFA 2.2
mass transition:	3-Methylpyrazole	3-Methylpyrazole	3-Methylpyrazole
m/z 83 > m/z 56	found	found	found
hours	[mg/kg dry weight]	[%]	mean [%]
0	0.253	83.8	83.2
	0.249	82.6
16	0.213	70.6	70.7
	0.213	70.8
24	0.198	65.5	65.5
	0.197	65.4
48	0.151	50.0	51.2
	0.158	52.4
64	0.056	18.6	20.3
	0.067	22.1
88	0.039	13.0	13.3
	0.041	13.5
168	0.0069	2.3	2.2
	0.0066	2.2
240	0.0054	1.8	1.8
	0.0055	1.8

Results of Definitive Test of 3-Methylpyrazole for LUFA 2.3

LUFA 2.3
mass transition:	3-Methylpyrazole	3-Methylpyrazole	3-Methylpyrazole
m/z 83 > m/z 56	found	found	found
days	[mg/kg dry weight]	[%]	mean [%]
0	0.265	87.7	88.2
	0.268	88.8
1	0.238	78.9	76.7
	0.225	74.5
3	0.172	56.9	53.6
	0.152	50.4
5	0.087	28.8	29.5
	0.091	30.2
7	0.069	22.8	21.5
	0.061	20.1
10	0.042	14.0	12.2
	0.031	10.4
14	0.020	6.6	7.3
	0.024	8.0
18	0.013	4.3	5.3
	0.019	6.2

Applicant's summary and conclusion

Conclusions:

The following DT50 and DT90 values were calculated using FOCUS_DegKin_v2. Single first-order (SFO) and first-order multi compartment (FOMC) kinetic models were tested and the best fit provided:
3-Methylpyrazole


LUFA 2.1: Loamy sand, SFO, DT50: 2.9 days DT90: 9.5 days
LUFA 2.2: Sandy loam, SFO, DT50: 40.9 hours(1.7 days), DT90: 135.9 hours (5.7 days)
LUFA 2.3: Sandy loam, SFO, DT50: 3.5 days DT90: 11.7 days

The results show that no (1H-Pyrazole-3-yl)methanol was formed in any of the soils.

Executive summary:

The objective of this study was to determine the rate of degradation of 3-Methylpyrazole in aerobic soil systems. The degradation behaviour of 3-Methylpyrazole in three standard soils was investigated following OECD 307 according to GLP.

Additionally, the appearance of (1H-Pyrazole-3-yl)methanol was checked.

 

In order to determine 3-Methylpyrazole and (1H-Pyrazole-3-yl)methanol, the validation of an analytical method was additionally required and the same three soils as in the main test were chosen. For method validation, each soil was fortified with 3-Methylpyrazole and (1H-Pyrazole-3-yl)methanol at the LOQ (0.015 mg/kg) and 20 x LOQ (0.3 mg/kg).

 

Results Main Test (OECD 307)

The degradation of 3-Methylpyrazole was investigated under aerobic conditions at 20 ± 2 °C in the dark for a maximum of 18 days (LUFA 2.3) for the German standard soils LUFA 2.1, LUFA 2.2  and LUFA 2.3.

The target rate of 0.3 mg/kg dry soil for 3-Methylpyrazole was selected for the aerobic soil degradation experiments.

The soil systems were acclimatized under a dynamic atmosphere of air to maintain aerobic conditions. The test period consisted of sampling intervals at

• LUFA 2.1: zero-time (initial value), 1, 2, 3, 5, 7, 10 and 14 days


• LUFA 2.2: zero-time (initial value), 16, 24, 48, 64, 88, 168 and 240 hours


• LUFA 2.3: zero-time (initial value), 1, 3, 5, 7, 10, 14 and 18 days

 

Additionally, soil specimens were assayed for (1H-Pyrazole-3-yl)methanol at all timepoints.

The mean recoveries 3-Methylpyrazole for the initial time specimens ranged from 83.2 to 89.7 % of the applied test item. The mean recoveries 3-Methylpyrazole decreased with time and accounted for mean values ranging from 1.4 to 5.3 % at experimental end.

The following DT₅₀ and DT₉₀ values were calculated using FOCUS_DegKin_v2. Single first-order (SFO) and first-order multi compartment (FOMC) kinetic models were tested and the best fit provided:

3-Methylpyrazole

Soil	Soil texture USDA	Model	DT50	DT90	Error level Chi^2
LUFA 2.1	Loamy sand	SFO	2.9 days	9.5 days	14.4
LUFA 2.2	Sandy loam	SFO	40.9 hours (1.7 days)	135.9 hours (5.7 days)	13.2
LUFA 2.3	Sandy loam	SFO	3.5 days	11.7 days	5.3

The results show that no (1H-Pyrazole-3-yl)methanol was formed in any of the soils.