Methyl (R)-2-(4-(3-chloro-5-trifluoromethyl-2-pyridyloxy)phenoxy)propionate

Toxicity to soil microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to soil microorganisms

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Qualifier:

according to guideline

Guideline:

OECD Guideline 217 (Soil Microorganisms: Carbon Transformation Test)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

HALOXIFOP R ME
Lot #: OG 13150101
Purity: Not reported

Analytical monitoring:

no

Vehicle:

yes

Remarks:

Acetone

Details on preparation and application of test substrate:

- Stock solution: 10.5 mg of test substance was dissolved in 10 mL of acetone, to obtain a solution with concentration of 1.00 mg/mL of test substance
- Treatment solution 1 (MUR): 240.0 µL of the stock solution was diluted in a final volume of 10 mL of acetone, resulting in a treatment (solution 1) of 24.0 µg/mL; A volume of 500 µL of the treatment solution was added to 150 g of soil in order to give a concentration of 0.08 mg/kg of soil.
- Treatment solution 2 (5MUR): 1200.0 µL of the stock solution was diluted in a final volume of 10 mL of acetone, resulting in a treatment (solution 2) of 120.0 µg/mL. A volume 500 µL of the treatment solution was added to 150 g of soil in order to give a concentration of 0.40 mg/kg of soil.

Test organisms (inoculum):

soil

Total exposure duration:

28 d

Test temperature:

18 to 21°C

Moisture:

40-60%

Details on test conditions:

TEST SYSTEM
- Test container: Glass flask
- Amount of soil: 150 g
- No. of replicates per concentration: 3
- No. of replicates per control: 3

SOIL INCUBATION
- Method: Series of individual subsamples

SOURCE AND PROPERTIES OF SUBSTRATE
- Depth of sampling: 0-20 cm

LR soil
- Soil texture: Typic Hapludox
- sand: 140 g/kg
- silt: 130 g/kg
- clay: 730 g/kg
- Soil taxonomic classification: Latossolo Vermelho Distroferrico tipico
- Soil classification system: Empresa Brasileira de Pesquisa Agropecuaria - EMBRAPA/CNPS 1999, and Soil Taxonomy 1990
- pH (CaCl2): 4.2
- Organic matter: 25.0 g/dm3
- Calcium: 9.0 mmolc/dm3
- Magnesium: 6.0 mmolc/dm3
- Potassium: 1.3 mmolc/dm3
- Aluminum: 8.0 mmolc/dm3
- Phosphorus: 3.0 mg/dm3
- Micronutrients: Bore: 0.14 mg/dm3; Copper: 2.6 mg/dm3; Iron: 16.0 mg/dm3; Manganese: 7.4 mg/dm3; Zinc: 0.6 mg/dm3
- Initial microbial biomass: 0.20 mg of C/g soil

LE soil
- Soil texture: Rhodic Hapludox
- sand: 620 g/kg
- silt: 160 g/kg
- clay: 220 g/kg
- Soil taxonomic classification: Latossolo Vermelho Distrofico psamitico
- Soil classification system: Empresa Brasileira de Pesquisa Agropecuaria - EMBRAPA/CNPS 1999, and Soil Taxonomy 1990
- pH (CaCl2): 5.0
- Organic matter: 20.0 g/dm3
- Calcium: 125 mmolc/dm3
- Magnesium: 110 mmolc/dm3
- Potassium: 3.7 mmolc/dm3
- Aluminum: 0.0 mmolc/dm3
- Phosphorus: 72.0 mg/dm3
- Micronutrients: Bore: 0.4 mg/dm3; Copper: 3.1 mg/dm3; Iron: 94.0 mg/dm3; Manganese: 21.6 mg/dm3; Zinc: 2.2 mg/dm3
- Initial microbial biomass: 0.11 mg of C/g soil

Nominal and measured concentrations:

0.08 and 0.40 mg/kg soil

Key result

Duration:

28 d

Basis for effect:

other: nitrogen and carbon cycles

Remarks:

at 0.08 and 0.40 mg a.i./kg

Remarks on result:

other: The test substance did not affect the nitrogen and carbon cycles after 28 days of incubation. Difference lower than 25% in the treatments when, compared with the control, is not considered inhibition.

Conclusions:

The test substance did not affect the carbon cycles after 28 days of incubation

Executive summary:

This study was carried out in order to determine the side effects of test substance on soil microorganisms: Carbon Cycle, using LR (Rhodic Hapludox) and LE (Typic Hapludox) soils. The study was conducted following OECD guideline 217. This assay was carried out with three replicates in glass flasks containing 150 g of soil treated with organic matter with C/N ratio 15/1 representing maximum of 0.5 % of soil dry weight (1 cm3 was added per 150 g of dry soil). Control with organic matter was utilized. Two concentrations of the active ingredient were added, 0.08 and 0.40 mg of the active ingredient/kg of soil. These soils were incubated at temperature of 18 to 21°C for 28 days. Samples were taken from the flasks at 0, 7, 14, and 28 days and analyzed microbial activity. The results showed that test substance did not have adverse effect on carbon cycle on LR and LE for the two rates used in this experiment, after 28 days of incubation.

Description of key information

28day NOEC = 0.4 mg/kg; OECD 217; Reliability = 1

Key value for chemical safety assessment

Long-term EC10 or NOEC for soil microorganisms:

0.4 mg/kg soil dw

Additional information

Test substance did not affect the nitrogen and carbon cycles after 28 days of incubation at the tested concentrations 0.08 and 0.40 mg a.i./kg