α-(2,4-dichlorophenyl)-1H-imidazole-1-ethanol

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

Study period:

29-10-2009 to 15-06-2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 216 (Soil Microorganisms: Nitrogen Transformation Test)

Version / remarks:

January 2000

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 217 (Soil Microorganisms: Carbon Transformation Test)

Version / remarks:

January 2000

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: 00512242
- retest date: 27/06/2013
- purity: 100.3% (w/w)

Analytical monitoring:

no

Details on sampling:

- Concentrations: control, solvent control, 0.4 mg/kg soil dw, 2 mg/ kg soil dw
- Sampling method:
samples of treated soil were taken from each replicate at 0 day, 7 days, 14 days, 28 days, 42 days. The following parameters were determined: soil dry weight, pH, nitrogen turnover and short-term respiration.
The short-term respiration 1000 g of soil for each treatment replicate was transferred into the reaction vessels and was mixed with the quantity of glucose to achieve an optimum respiration rate. the incubation period was between 20 -24h at 20°C+-2. The rate of oxygen consumption during measurement period was determined within the first 12 hours. CO2 produced during short-term respiration was calculated from consumed O2, based on stoichiometry of O2 consumption and CO2 production during respiration. The inhibition of CO2 production was calculated by comparing the values of the soil samples treated with the test item with the untreated solvent control. Soil nitrification was determined by measuring the NO3 --N content of aqueous soil extracts. 50 grams of soil of each treatment were made up to a final volume of 200 mL with a 0.1 % alum solution. The samples were shaken for 30 minutes. The aqueous supernatant was filtered and 50 mL of this filtrate were used for the nitrate measurements using NO3- selective electrode. The nitrate content of the soil was calculated as mg NO3 -N per kg soil dw.

Vehicle:

no

Details on preparation and application of test substrate:

AMENDMENT OF SOIL
- Type of organic substrate: quarts

APPLICATION OF TEST SUBSTANCE TO SOIL
- Method: T000824 was applied at 0.4 mg/kg soil dw and 2 mg/kg soil dw. The soil was mixed with finely ground lucerne meal before application. The final concentration of the dried lucerne meal was 0.5% of the soil dw.
200 mg glucose/100 g soil wet weight was found to be the optimum and used in the test.
After addition of the test item to the quartz sand and after evaporationn of the acetone, the treated quartz sand was mixed with the soil. The solvent control was treated with acetone treated quartz and the control was untreated with the amount of deionised water added to achieve 45% of maximum moisture content. Each treatment group contained 3300 g moist soil for the nitrogen turnover and the short-term respiration

Test organisms (inoculum):

soil

Total exposure duration:

42 d

Test temperature:

20°C

Moisture:

45%

Details on test conditions:

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
Nitrogen turnover
- History of site: agricultural field in Offenbach (Bildgarten)
- Vegetation cover: not cultivated since 2007
- Treatments with pesticides or fertilizers: no
- Depth of sampling: 0 - 20 cm (mixed sample)
- Soil texture: clayey sand
- % sand: 82.6
- % silt: 11.7
- % clay: 5.7
- pH (in water): 6.74
- Initial nitrate concentration for nitrogen transformation test (mg nitrate/kg dry weight): 9.89
- Maximum water holding capacity (in % dry weigth): 31.61
- Cation exchange capacity (mmol/kg): 9.5 meq/100 g
- Initial microbial biomass as % of total organic C: 0.95

Short-term Respiration:
- History of site: agricultural field in Offenbach (Bildgarten)
- Vegetation cover: not cultivated since 2007
- Treatments with pesticides or fertilizers: no
- Depth of sampling: 0 - 20 cm (mixed sample)
- Soil texture: clayey sand
- % sand: 57.1
- % silt: 40.6
- % clay: 2.3
- pH (in water): 7.25
- Initial nitrate concentration for nitrogen transformation test (mg nitrate/kg dry weight): 8.23
- Maximum water holding capacity (in % dry weigth): 29.42
- Cation exchange capacity (mmol/kg): 10 meq/100 g
- Initial microbial biomass as % of total organic C: 1.11

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : soil dry weight, pH, nitrogen turnover and short-term respiration

Nominal and measured concentrations:

0.4 and 2 mg/kg

Reference substance (positive control):

yes

Remarks:

Dinoterb

Duration:

42 d

Dose descriptor:

EC50

Effect conc.:

>= 2 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

nitrate formation rate

Duration:

42 d

Dose descriptor:

EC50

Effect conc.:

>= 2 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

respiration rate

Details on results:

T000824 had no effects on the nitrogen turnover and short-term respiration at 2 mg/kg soil dw.

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: Dinoterb had distinc effects on both short-term respiration and nitrogen turnover after 28 days. (increase of the nitrogen level of + 121% increase of the nitrate transformation rate of +241%) and short-term respiration (-45.8% inhibition) in a field soil tested at 13.3 mg/ a.i./kg soil dw 28 days after application

Reported statistics and error estimates:

Test on normality and homogeneity of data using Shapiro-Wilk's test, Bartlett's and Levine's test followed by Dunnett's t-test

For the nitrogen turnover, the deviation between soil treated with T000824 and solvent control was -12.7 % for the 0.4 mg/kg soil dw treatment after 28 days and -11.1% for the 2 mg/kg soild dw treatment after 42 days.

For the short-term respiration the deviations between soil treated with T000824 and solvent control were -12.5% measured forthe 0.4 mg/kg soil dw and -17.1% for the 2 mg/kg soild dw treatment after 28 days.

Validity criteria fulfilled:

yes

Conclusions:

Based on the results of this study and in accordance with the OECD guidelines 216 and 217, T000824 had no adverse effect on short-term respiration and no long-term influence on nitrogen turnover in a field soil tested up to and including 2 mg/kg soil dry weight at study termination (deviation between treatments and solvent control < 25%).

Description of key information

The effects of T000824 on soil microflora were assessed in a test that measured nitrogen turnover (mineralisation) and carbon transformation (short-term substrate-induced respiration) following an application of the test item to soil in accordance with OECD 216 and 217. The test was terminated after 42 days for nitrogen turnover and after 28 days for short-term respiration. Based on the results of this study, T000824 had no adverse effect on short-term respiration and no long-term influence on nitrogen turnover in a field soil tested up to and including 2 mg/kg soil dry weight at study termination (deviation between treatments and solvent control < 25%).