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Ecotoxicological information

Toxicity to soil microorganisms

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Reference
Endpoint:
toxicity to soil microorganisms
Type of information:
experimental study
Adequacy of study:
key study
Study period:
10 Jul - 07 Aug 2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 217 (Soil Microorganisms: Carbon Transformation Test)
Version / remarks:
2000
GLP compliance:
yes (incl. certificate)
Remarks:
Staatsministerium für Umwelt und Landwirtschaft Freistaat Sachsen, Germany
Analytical monitoring:
no
Vehicle:
no
Details on preparation and application of test substrate:
AMENDMENT OF SOIL
- Type of organic substrate: glucose

APPLICATION OF TEST SUBSTANCE TO SOIL
- Method: The test item was applied as requested at test concentrations of 7.53 mg/kg and 37.62 mg/kg soil dry weight. The soil of each treatment was incubated as a series of 3 replicates (sub-samples).
- see below "Any other information on materials and methods incl. tables"
Test organisms (inoculum):
soil
Total exposure duration:
28 d
Test temperature:
18.4 - 20.7 °C in a climatic room
Moisture:
Water content 14.93 - 15.65 g/100 g soil d.w. (equivalent to 42.46 - 44.50 % of WHC)
Details on test conditions:
TEST SYSTEM
- Test container (type, material, size): steel, 4 L
- Amount of soil: 1110.50 g wet soil; 1000 g dry soil
- No. of replicates per concentration: 3
- No. of replicates per control: 3
- No. of replicates per reference: 3

SOIL INCUBATION
- Method: series of individual subsamples

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Geographical reference of sampling site (latitude, longitude): Canitz, Germany, 12.694435960 degrees East; 51.403774567 degrees North
- History of site: agriculturally utilised soil
- Vegetation cover: fallow ground
- Application of fertilisers: none since 2003
- Depth of sampling: 20 cm
- Soil texture
According to USDA:clay (< 0.002 mm): 9.6
silt (0.002 - 0.050 mm): 35.5
sand (0.05 - 2.0 mm): 54.9
soil class: sandy loam
According to ISO 11277:
clay (< 0.002 mm): 9.6
silt (0.002 - 0.063 mm): 37.1
sand (0.063 - 2.0 mm): 53.3
soil class (DIN 4220): loamy sand
- pH (in water): 6.5
- Water holding capacity: 35.17 g/100 g soil d.w.
- Cation exchange capacity: 9.2 cmol+/kg soil
- Pretreatment of soil: The soil was dried and passed through a 2 mm mesh sieve.
- Storage (condition, duration): at a temperature of approx. 4 °C in containers under aerobic conditions in the dark
- Initial microbial biomass as % of total organic C:
Corg [%]: 1.49
Humus content [%]: 2.56
Carbon content of microbial biomass [mg C/100 g soil d.w.]: 32.62 = 2.19 % of Corg.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :

VEHICLE CONTROL PERFORMED: yes/no

RANGE-FINDING STUDY
- Test concentrations:
- Results used to determine the conditions for the definitive study:
Nominal and measured concentrations:
Nominal: Control, 7.53 mg test item/kg dry soil and 37.63 mg test item/kg dry soil.
Reference substance (positive control):
yes
Remarks:
2-tert-Butyl-4,6-dinitrophenol
Duration:
28 d
Dose descriptor:
EC10
Effect conc.:
> 37.63 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
respiration rate
Remarks:
oxygen consumption
Remarks on result:
other: highest test concentration
Details on results:
- The test item caused no adverse effects (deviation from control <25 %, OECD 217) on soil carbon transformation (measured as O2-consumption) at the end of the 28-day incubation period.
- The coefficients of variation in the control group of the carbon transformation test were maximum 2.3 % (demanded range ≤15 %).
Results with reference substance (positive control):
In the most recent test, dated 04.01.to 01.02.2013, the toxic standard dinoterb caused effects of -39.3 % and -45.2 % (required ≥ 25 %) on the carbon transformation in a field soil at the tested concentrations of 16.00 mg and 27.00 mg dinoterb per kg soil dry weight, respectively, 28 days after application.
Validity criteria fulfilled:
yes

Description of key information

EC10 (28 d) > 37.65 mg/kg soil dw (OECD 217)

Key value for chemical safety assessment

Additional information

One study is available on the toxicity 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 soil microorganisms. The study was conducted according to OECD Guideline 217 and GLP (Schulz, 2013). The test soil was exposed to the test substance at nominal concentrations of 7.53 and 37.63 mg test item/kg dry soil for 28 days. The test item caused no adverse effects on soil carbon transformation at the end of the 28-day incubation period. The inhibition on soil carbon transformation was 3.3% at the end of the study. The EC10 was thus determined to be > 37.65 mg/kg soil d.w..