4-(4-isopropoxyphenylsulfonyl)phenol

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:

from 2003-10-22 to 2004-02-09

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 217 (Soil Microorganisms: Carbon Transformation Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

yes

Details on preparation and application of test substrate:

D-8 was not soluble in water, therefore, a solution in acetone was prepared and dropped onto quartz sand. The organic solvent was allowed to evaporate and the quartz sand was mixed into the soil by means of a laboratory mixer. For the control, only acetone treated quartz sand was mixed into the soil.
Application of the Test Item:
A stock solution was prepared by suspending 8000 mg D-8 in 20 mL acetone and a dilution was prepared.
Afterwards, adequate amounts of the stock solution and the dilution were dropped onto quartz sand and the organic solvent was allowed to evaporate. The test item containing quartz sand was mixed into the soil using a laboratory mixer; in the course of the procedure the soil was ventilated and moistened with an adequate amount of deionised water. The soil water contents were adjusted to approximately 46 – 47 % of the water holding capacity (WHC).

Test organisms (inoculum):

soil

Total exposure duration:

28 d

Test temperature:

19.8 to 21.9 °C

Moisture:

46.3 - 50.6 % of the WHCmax

Organic carbon content (% dry weight):

1.31

Nitrogen content (% dry weight):

12.6

Details on test conditions:

Test Conditions
Test units: plastic boxes with approximately 800 g dw soil
Surrounding Type: air-conditioned room
Temperature: 19.8 °C to 21.9 °C
Light Regime: in the dark
Recording: The temperature was recorded by means of an electronic thermometer. The thermometer reading (min/max value) was documented once a week and is part of the raw data.

Nominal and measured concentrations:

Nominal concentrations: control and 62.5, 125, 250, 500 and 1000 mg test item/kg soil dry weight
No measured concentrations.

Reference substance (positive control):

yes

Remarks:

Dinoterb and Dinoterb Acetate at 13.3 and 16 mg/kg dry soil

Key result

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

respiration rate

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

>= 1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

respiration rate

Details on results:

The soil respiration of the D-8 treated soils differed by less than 25 % (trigger value given by the OECD 217 test guideline) from control after 28 days of incubation. The maximum difference was 2.23 % stimulation and 6.13 % inhibition.

Results with reference substance (positive control):

The inhibition of soil respiration and nitrogen turnover by the toxic standard was determined at least once a year as a means of assuring that the laboratory test conditions are adequate and have not changed significantly. For testing the toxic standards, soil from the same site as for testing D-8 was used. In separate studies, the reference items Dinoterb and Dinoterb Acetate produced in the soil the expected level of effect (more than 25 % stimulation / inhibition in nitrogen turnover and soil respiration).

Reported statistics and error estimates:

Data of the short term respiration were tested for normality and homogeneity of variance using R/S-Test Test (alpha = 0.05) and Bartlett´s-Test (alpha = 0.05). Student-t-test (pair wise comparison, two sided, alpha = 0.05) was used for analysis. The software used to perform the statistical analysis was EASY ASSAY, Multiple Testing, SpiRiT, Version 4.0.

Table 1: Carbon Turnover Test: Effects of D-8 on Soil Respiration (Mean Values)

treatment group	day 0			day 28
	R^1)	SD	%^2)	R^1)	SD	%^2)	Sig.^3)
control	13.416	0.836	-	11.185	0.613	-	-
D-8 62.5 mg/kg	13.328	0.249	-0.66	11.174	0.825	-0.10	n. s.
D-8 125 mg/kg	13.076	0.443	-2.53	11.434	0.765	2.23	n. s.
D-8 250 mg/kg	12.955	0.208	-3.44	10.677	0.704	-4.54	n. s.
D-8 500 mg/kg	13.822	0.420	3.03	10.774	0.720	-3.67	n. s.
D-8 1000 mg/kg	13.247	0.719	-1.26	10.499	0.071	-6.13	n. s.

1): soil respiration [mg CO2/ kg dry weight h], mean of 3 replicates
2): % deviation of corresponding control
3): * significance to corresponding control (according Student-t-test, two sided α = 0.05)
n. s.: no significance to corresponding control
SD: Standard deviation
-: not applicable

The soil respiration of the D-8 treated soils differed by less than 25 % (trigger value given by the OECD 217 test guideline) from the control after 28 days of incubation. The maximum difference was 2.23 % stimulation and 6.13 % inhibition.

Based on the results of this study, D-8 had no significant impact on soil microflora carbon mineralisation when applied at concentrations up to 1000 mg/kg soil dry weight. It can be concluded that D-8 will not have any long-term influence on soil microflora. An ECx-value could not be calculated. It can be considered that the EC50 of D-8 is above 1000 mg/kg soil dry weight. The NOEC is considered to be equal or greater than 1000 mg/kg soil dry weight.

 

Validity criteria fulfilled:

yes

Conclusions:

Based on the results of this study, D-8 had no significant impact on soil microflora carbon mineralisation up to 1000 mg/kg soil dry weight. It can be concluded that D-8 will not have any long-term influence on soil microflora. It is considered that the EC50 of D-8 is above 1000 mg/kg soil dry weight. The NOEC is considered to be equal or greater than 1000 mg/kg soil dry weight.

Executive summary:

The Effects of D-8 on the Activity of the Soil Microflora in the Laboratory were tested according to OECD 217. The purpose of this study was to assess the effects of D-8 on the activity (carbon mineralisation) of the soil microflora in a laboratory setup. Dinoterb and Dinoterb Acetate were used as toxic standards under the same test conditions. A solution of D-8 in acetone was prepared and dropped onto quartz sand. After the solvent has evaporated, the quartz sand was mixed with the test soil. The following concentrations were tested - 0, 62.5, 125, 250, 500 and 1000 mg test item/kg soil dry weight. The system was incubated for 28 days. The soil respiration of the D-8 treated soils differed by less than 25 % (trigger value given by the OECD 217 test guideline) from control after 28 days of incubation. The maximum difference was 2.23 % stimulation and 6.13 % inhibition. Based on the results of this study, D-8 had no significant impact on soil microflora carbon mineralisation when applied at concentrations up to 1000 mg/kg soil dry weight. It can be concluded that D-8 will not have any long-term influence on soil microflora. It is considered that the EC50 of D-8 is above 1000 mg/kg soil dry weight. The NOEC is considered to be equal or greater than 1000 mg/kg soil dry weight.

Description of key information

Based on the results of this study, D-8 had no significant impact on soil microflora carbon mineralisation up to 1000 mg/kg soil dry weight. It can be concluded that D-8 will not have any long-term influence on soil microflora. It is considered that the EC50 of D-8 is above 1000 mg/kg soil dry weight. The NOEC is considered to be equal or greater than 1000 mg/kg soil dry weight.

Key value for chemical safety assessment

Long-term EC10 or NOEC for soil microorganisms:

1 000 mg/kg soil dw

Additional information

The Effects of D-8 on the Activity of the Soil Microflora in the Laboratory were tested according to OECD 217. The purpose of this study was to assess the effects of D-8 on the activity (carbon mineralisation) of the soil microflora in a laboratory setup. Dinoterb and Dinoterb Acetate were used as toxic standards under the same test conditions. A solution of D-8 in acetone was prepared and dropped onto quartz sand. After the solvent has evaporated, the quartz sand was mixed with the test soil. The following concentrations were tested - 0, 62.5, 125, 250, 500 and 1000 mg test item/kg soil dry weight. The system was incubated for 28 days. The soil respiration of the D-8 treated soils differed by less than 25 % (trigger value given by the OECD 217 test guideline) from control after 28 days of incubation. The maximum difference was 2.23 % stimulation and 6.13 % inhibition. Based on the results of this study, D-8 had no significant impact on soil microflora carbon mineralisation when applied at concentrations up to 1000 mg/kg soil dry weight. It can be concluded that D-8 will not have any long-term influence on soil microflora. It is considered that the EC50 of D-8 is above 1000 mg/kg soil dry weight. The NOEC is considered to be equal or greater than 1000 mg/kg soil dry weight.