Reaction mass of tetrahydroxysilane and choline chloride and calcium chloride and water

Toxicity to soil microorganisms

Administrative data

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:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 216 (Soil Microorganisms: Nitrogen Transformation Test)

Test guideline 2

Qualifier:

according to guideline

Guideline:

OECD Guideline 217 (Soil Microorganisms: Carbon Transformation Test)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Reaction mass of tetrahydroxysilane and choline chloride and calcium chloride and water

IUPAC Name:

Reaction mass of tetrahydroxysilane and choline chloride and calcium chloride and water

Test material form:

liquid

Specific details on test material used for the study:

Lot 08E20

Sampling and analysis

Analytical monitoring:

no

Test substrate

Vehicle:

no

Details on preparation and application of test substrate:

Actisil was dissolved in deionised water to produce solutions that would produce the equivalent of 2 L/ha and 10 L/ha when added to additional deionised water and soil. For both the carbon and the nitrogen transformation test, the moisture content of the soil was adjusted to approximately 40% of the maximum water holding capaity (MWHC) and this achieved via the dosing of each treatment group with the test solution dose, plus additional water as required.

Test organisms

Test organisms (inoculum):

soil

Study design

Total exposure duration:

28 d

Test conditions

Moisture:

35%

Details on test conditions:

Soil: LUFA 2.3
sand content: 60.8%
pH water: 7.1
organic carbon content: 0.98%
microbial biomass: 1.9% of total organic carbon

replicates: 3 for both test
Each replicate for both tests was contained in a 2.0 L plastic container (16.7 x 16.7 x 9 cm) and perforated with a single 3 mm diameter hole to enable aerobic conditions to previal throughout the test.

soil amended with ground lucerne (0.5% w:w) for the nitrification assay.

The products of the process of nitrification were extracted from the soil on Day 0, 7, 14 and 28.
Substrate-induceed (glucose) respiration measurements were made on Day 0, 7, 14 and 28 by measuring the carbon dioxide evolution over a 12 hour period.

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

28 d

Dose descriptor:

EC10

Effect conc.:

> 10 other: L/ha

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

nitrate formation rate

Effect concentrations 2

Key result

Duration:

28 d

Dose descriptor:

EC25

Effect conc.:

> 10 other: L/ha

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

respiration rate

Details on results:

The soil nitrification phase was determined on Day 28 as the difference between the control (water) mean and the treatments was less than 25%. The nitrate level in the 2 L Actisil/ha dry soil test rate was -3.2% from the control mean and the 10 L Actisil/ha dry soil rate was +1.7% at Day 28. The average rate of production of nitrate from Day 0 to Day 28 for the 2 L Actisil/ha test rate was -5.6% different from the control mean and a difference of 3.4% was recorded in the 10 L Actisil/ha treatment group. The percentage variation winthin the control vessels for nitrate concentration (mg/kg dry soil) between replicates ranged from -0.7% to +1.2% on Day 2, thus fulfilling the validity criterion for control treatment replication.

The soil respiration phase was determined on Day 28, according to the guidelines. the difference between the mean control (deionised water) rate of carbon dioxide production (mgCO2/kg/hr) and in any treamtnet group was less than 25% by Day 28. The caron dioxide produced by the 2 L Actisil/ha dry soil basis was +10.8% from the mean of the control group and, similarly, the 10 L Actisil/ha dry soil group was +19.6% on Day 28.
The percentage variation within the control samples (deionised water) for carbon dioxide production (mg Co2/kg/hr) ranged from -5.2% to +5.7% on Day 28. This data fulfils the validity criterion that the variation between control replicates from the average should not be greater than 15%.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

At Day 28, average soil carbon respiration rates and nitrate production in soils treated with 2 L/ha and 10 L/ha Actisil dry soil were not greater than 25% from the control means. For this reason it is considered that the test item, Actisil, at the rates shown is unlikely to have any long term effect on the soil microflora which are repsonsible for carbon breakdown and nitrification in the soil.

The study satisfied the OECD 216 (2000) and OECD 217 (2000) validity criterion that the variation between replicate control samples (deionised water) should not be greater than +- 15% at Day 28 when the difference between the controls and the treatments was tested.