5-amino-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-(ethylsulfinyl)-1H-pyrazole-3-carbonitrile

Toxicity to soil microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to soil microorganisms

Type of information:

experimental study

Adequacy of study:

key study

Study period:

07 Jun - 12 Aug 1999

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: method described in EPPO Bulletin 24, 1-16 (1994)

Qualifier:

according to guideline

Guideline:

other: ISO 10381-6, adopted 1993, for soil collection

GLP compliance:

yes (incl. QA statement)

Remarks:

The Department of Health of the Government of the United Kingdom, date of inspection 26 Aug 1999

Analytical monitoring:

no

Vehicle:

yes

Details on preparation and application of test substrate:

APPLICATION OF TEST SUBSTANCE TO SOIL
- Method: The test substance was made up in HPLC grade acetone and dried onto 100 g of acid washed quartz sand. The actual amount weighed was 12.01 mg RPA 107382. Drying took place in a glass bottle at approximately 20 °C over a five day period under an extractor fan in a cabinet in which the light was excluded. Immediately prior to the start of the test the bottle was sealed and placed on a roller for approx. 30 minutes (at approx. 60 rpm) in order to thoroughly homogenise the RPA 107382-amended sand. The required amounts of RPA 107382-amended sand were then weighed and added to each replicate soil sample (10 g to each replicate to be used for soil respiration, this corresponds to an amendment of 1.2 mg/kg dry weight equivalent). The same amounts of acetone amended acid washed quartz sand, but without test substance, were added to the control replicates.

VEHICLE:
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): acetone
- Evaporation of vehicle before use: yes

Test organisms (inoculum):

soil

Total exposure duration:

28 d

Test temperature:

19 - 23 °C

Moisture:

45% water holding capacity

Details on test conditions:

TEST SYSTEM
- Testing facility: CEM Analytical Services Ltd, Glendale Park, Fernbank Road, North Ascot, Berks, SL5 8JB, UK
- Test container for the soil respiration test: closed 2.5 L square plastic containers, 16.7 cm2, 9 cm deep, hole of 3 mm in the lid
- Amount of soil: 1000 g dry weight equivalent for soil respiration
- No. of replicates per concentration: 3
- No. of replicates per vehicle control: 3

SOIL INCUBATION
- Method: series of individual subsamples
- Soil pH during the test: 7.1 - 7.4

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Geographical reference of sampling site (latitude, longitude): OS grid reference TM 272 526
- Source: Levington Agriculture Ltd, Ipswitch, Suffolk, UK
- Vegetation cover: grassland
- Treatments with pesticides or fertilizers: no treatment within the last 5 years
- Depth of sampling: upper 20 cm layer
- Soil texture
- % sand: 67.9
- % silt: 15.3
- % clay: 16.9
- Soil taxonomic classification: Loamy Sand
- Soil classification system: BBA classification
- Particle size: 67.6% of particles between 63 and 2000 µm
- pH (in water): 6.5
- Maximum water holding capacity (in % dry weight): 53.6
- Cation exchange capacity (meq/100 g):16.4
- Storage (condition, duration): at approx. 4 °C for 31 days prior to acclimation for the test
- Acclimation: The soil was moisturised to 45% water holding capacity (WHC) and held in the dark at 20 + 2 °C
- Initial microbial biomass as % of total organic C: 3.5

PREPARATION OF SOIL FOR THE TEST: At the start of the test, samples of the soil were amended with 0.5% w/w ground lucerne. The lucerne was used as a nitrogen amendment and had a total carbon content of 42.45 % w/w and total nitrogen content of 3.03 % w/w giving a C:N ratio of 14:1.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable):
Soil respiration was measured within the first 24 h of dosing, after 14 days and after 28 days.

VEHICLE CONTROL PERFORMED: yes

Nominal and measured concentrations:

Nominal: 1.2 mg/kg dry soil, equivalent to 900 g/ha

Reference substance (positive control):

yes

Remarks:

dinoseb

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

>= 900 g/ha

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

respiration rate

Results with reference substance (positive control):

The reference test with 1 and 10 mg dinoseb/kg dry soil was carried out between 19 Mar 1999 and 22 Apr 1999.
Resulting variations for 10 mg/kg dry soil treatment for 28 days compared to the control:
Soil respiration: - 28.5%

The test substance RPA 107382 when present in soil at a concentration of 900 g/ha which is twice the concentration expected from the foliar use of the maximum annual recommended rate of 900 g/ha did not give rise to any statistically significant effects greater than ± 3 % of the control values on soil microflora respiration.

Table 1: Soil respiration measurements after 25 h, 14 d and 28 d of exposure

Treatment	Mean CO2 production (mL CO2/100 g soil*h) (SD)			% variation from control mean
	25 h	14 d	28 d	25 h	14 d	28 d
Control with lucerne	2.47 (0.180)	1.91 (0.068)	1.45 (0.014)	-	-	-
Treated soil	2.34 (0.082)	2.02 (0.023)	1.50 (0.027)	-5.2	+5.5	+2.9

Table 2: Validity criteria for OECD 217.

Criterion from the guideline	Outcome	Validity criterion fulfilled
The variation between replicate control samples should be less than ± 15%.	< 15%	yes

Validity criteria fulfilled:

yes

Remarks:

For further details please refer to “Any other information on results incl. tables”.

Reference 2

Endpoint:

toxicity to soil microorganisms

Type of information:

experimental study

Adequacy of study:

key study

Study period:

07 Jun - 12 Aug 1999

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: method described in EPPO Bulletin 24, 1-16 (1994)

Qualifier:

according to guideline

Guideline:

other: ISO 10381-6, adopted 1993, for soil collection

GLP compliance:

yes (incl. QA statement)

Remarks:

The Department of Health of the Government of the United Kingdom, date of inspection 26 Aug 1999

Analytical monitoring:

no

Vehicle:

yes

Details on preparation and application of test substrate:

APPLICATION OF TEST SUBSTANCE TO SOIL
- Method: The test substance was made up in HPLC grade acetone and dried onto 100 g of acid washed quartz sand. The actual amount weighed was 12.01 mg RPA 107382. Drying took place in a glass bottle at approximately 20 °C over a five day period under an extractor fan in a cabinet in which the light was excluded. Immediately prior to the start of the test the bottle was sealed and placed on a roller for approx. 30 minutes (at approx. 60 rpm) in order to thoroughly homogenise the RPA 107382-amended sand. The required amounts of RPA 107382-amended sand were then weighed and added to each replicate soil sample (0.5 g amounts were added to each nitrogen transformation replicate, this corresponds to an amendment of 1.2 mg/kg dry weight equivalent). The same amounts of acetone amended acid washed quartz sand, but without test substance, were added to the control replicates.

VEHICLE:
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): acetone
- Evaporation of vehicle before use: yes

Test organisms (inoculum):

soil

Total exposure duration:

28 d

Test temperature:

19 - 23 °C

Moisture:

45% water holding capacity

Details on test conditions:

TEST SYSTEM
- Testing facility: CEM Analytical Services Ltd, Glendale Park, Fernbank Road, North Ascot, Berks, SL5 8JB, UK
- Test container for the N transformation test: closed 500 mL cylindrical plastic pots, 9 cm diameter, 7.7 cm deep, hole of 3 mm in the lid
- Amount of soil: 50 g dry weight equivalent for N transformation
- No. of replicates per concentration: 3
- No. of replicates per vehicle control: 3

SOIL INCUBATION
- Method: series of individual subsamples
- Soil pH during the test: 7.1 - 7.4

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Geographical reference of sampling site (latitude, longitude): OS grid reference TM 272 526
- Source: Levington Agriculture Ltd, Ipswitch, Suffolk, UK
- Vegetation cover: grassland
- Treatments with pesticides or fertilizers: no treatment within the last 5 years
- Depth of sampling: upper 20 cm layer
- Soil texture
- % sand: 67.9
- % silt: 15.3
- % clay: 16.9
- Soil taxonomic classification: Loamy Sand
- Soil classification system: BBA classification
- Particle size: 67.6% of particles between 63 and 2000 µm
- pH (in water): 6.5
- Initial nitrate concentration for nitrogen transformation test (mg nitrate/kg dry weight): approx. 15 mg/kg
- Maximum water holding capacity (in % dry weight): 53.6
- Cation exchange capacity (meq/100 g):16.4
- Storage (condition, duration): at approx. 4 °C for 31 days prior to acclimation for the test
- Acclimation: The soil was moisturised to 45% water holding capacity (WHC) and held in the dark at 20 + 2 °C
- Initial microbial biomass as % of total organic C: 3.5

PREPARATION OF SOIL FOR THE TEST: At the start of the test, samples of the soil were amended with 0.5% w/w ground lucerne. The lucerne was used as a nitrogen amendment and had a total carbon content of 42.45 % w/w and total nitrogen content of 3.03 % w/w giving a C:N ratio of 14:1.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable):
Nitrogen transformation was measured within the first 24 h of dosing, after 14 days and after 28 days.

VEHICLE CONTROL PERFORMED: yes

Nominal and measured concentrations:

Nominal: 1.2 mg/kg dry soil = 900 g/ha

Reference substance (positive control):

yes

Remarks:

dinoseb

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

>= 900 g/ha

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

nitrate formation rate

Results with reference substance (positive control):

The reference test with 1 and 10 mg dinoseb/kg dry soil was carried out between 19 Mar 1999 and 22 Apr 1999.
Resulting variations for 10 mg/kg dry soil treatment for 28 days compared to the control:
Nitrogen transformation: + 95.6%

The test substance RPA 107382 when present in soil at a concentration of 900 g/ha which is twice the concentration expected from the foliar use of the maximum annual recommended rate of 900 g/ha did not give rise to any statistically significant effects greater than ± 6 % of the control values on soil nitrogen transformations after 28 days incubation.

Table 1: Effects of RPA 108723 on mean ammonium, nitrate and nitrite and total mineral nitrogen (N-min) concentrations

Treatment		Day 0 mg N/kg dry soil	Day 14 mg N/kg dry soil	Day 28 mg N/kg dry soil
Control with lucerne	Ammonium	9.42	0.35	< 0.26
	Nitrate	17.44	30.31	37.13
	Nitrite	< 0.26	< 0.26	< 0.26
	Total N-min	26.86	30.66	37.13
Treated soil	Ammonium	9.03	0.31	< 0.26
	Nitrate	17.49	31.99	38.80
	Nitrite	< 0.26	< 0.26	< 0.26
	Total N-min	26.52	32.30	38.80
	% Deviation from control	+ 1.3%	+ 5.3%	+ 4.5%

 

Table 2: Validity criteria for OECD 216.

Criterion from the guideline	Outcome	Validity criterion fulfilled
The variation between replicate control samples should be less than ± 15%.	< 15%	yes

Validity criteria fulfilled:

yes

Remarks:

For further details please refer to “Any other information on results incl. tables”.

Description of key information

EC50 (28d) > 1.2 mg/kg soil dw equivalent to 900.0 g/ha (EPPO Bulletin 24, 1-16) 
    
    
    
    

EPPO Bulletin 24, )1-16

Additional information

The effect of the test substance on soil microflora was investigated in one study that was carried out according to GLP and the method described in EPPO Bulletin 24, 1-16 (1994) using a loamy sand soil sample from grassland that had not been treated with pesticides within 5 years prior to the study. The substance was applied at a concentration of 1.2 mg/kg soil dry weight, equivalent to 900 g/ha. When present at this concentration, the substance did not give rise to any statistically significant effects greater than ± 3 % of the control values on soil microflora respiration and greater than ± 6 % of the control values on soil nitrogen transformation after 28 days incubation.