cis-2-tert-butylcyclohexyl acetate

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:

9th December 2016 to 11th January 2017

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)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Test organisms (inoculum):

soil

Total exposure duration:

28 d

Test temperature:

20 °C

Moisture:

Moisture: 53 % to 55 % of maximum water holding capacity (WHCmax).

Details on test conditions:

Application: As the test substance is volatile, the test item was directly pipetted into each bottle. For the control, water only was mixed into the soil.

For the determination of nitrate content at day 0 and 28, 250 mL 0.1 M KCl-solution was added to each relevant test vessel and agitated for one hour. The suspension was centrifuged (Multifuge 3s+, 4350 rpm) and the extracts were stored deep frozen until analysis.
Amounts of 74.0 mg and 72.2 mg sodium nitrite and potassium nitrate, respectively, were diluted in 1000 mL (sodium nitrite) and 100 ml (potassium nitrate) 0.1 M KCl to prepare the standard stock solutions for nitrite-N and nitrate-N + Nitrite-N determination. Appropriate aliquots of the stock solutions were automatically diluted by the dilution unity with 0.1 M KCl to prepare 6 standard solutions at a range of 0.5 mg/L to 3.0 mg/L for nitrite-N and at a range of 1.0 mg/L to 12.0 mg/L for nitrate-N + nitrite-N determination. Before photometric determination, frozen soil extracts were thawed. For determination, undiluted extracts were used. To get the nitrate-N concentrations, the nitrite-N values were subtracted from the nitrate-N + nitrite-N values.

Nominal and measured concentrations:

Nominal test concentrations were 0, 10, 32, 100, 320 and 1000 mg test substance/kg soil dry weight. Every concentration was done in 8 bottles (4 for day 0, 4 for day 28 sampling)

Reference substance (positive control):

yes

Remarks:

The reference item sodium chloride was tested in a GLP study (ibacon study code 116521080). Sodium chloride was tested at 16 g/kg soil dry weight.

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

100 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

nitrate formation rate

Details on results:

Effects of the test item on Nitrogen Transformation in a Silty Sand Soil

day 0 day 28 interval day 0-28
Mg/kg soil
dw NO3-N mg/kg dry weight Dev. %1 NO3-N mg/kg dry weight Dev. %1 sig.2 NO3-N mg/d/kg dry weight Dev. %1 sig.2
control 17.168 -- 22.997 -- -- 0.208 -- --
10 17.213 0.26 16.041 -30.25 n.s. -0.042 -120.19 n.s.
32 17.272 0.61 31.3363 36.26 n.s. 0.503 141.83 n.s.
100 17.242 0.43 31.253 35.90 n.s. 0.500 140.38 n.s.
320 17.172 0.02 0.083 -99.64 * -0.610 -393.27 *
1000 17.152 -0.09 5.994 -73.94 * -0.398 -291.35 *


1: Dev., deviation from control
2: sig.: significance according to Williams Multiple Sequential-t-test procedure, two sided, α = 0.05 (* = significant; n. s.: not significant)
3 one replicate was an outlier, only two replicates were used for calculation
LOQ: 0.083 mg Nitrate-N / kg Soil dry weight

Validity criteria fulfilled:

yes

Conclusions:

The (nitrate content and nitrate formation rate) of soil microorganisms when applied up to 100 mg test item/kg soil dry weight treatment. An application of 320 mg and 1000 mg/kg soil dry weight test substance caused a significant decrease of nitrate content and nitrate formation rate. The NOEC determination revealed that the NOEC is 100 mg test item/kg soil dw for nitrate content and nitrate rate.

Executive summary:

The toxicity of the test substance for soil microflora was tested according to OECD TG 216 using nitrogen transformation in soil. The concentrations tested were 0, 10, 32, 100, 320 and 1000 mg/kg dw soil. The reference substance was sodium chloride. The soil used was abiologically active agricultural soil: Silty sand. The effect parameter was NO3-nitrogen production after 28 days exposure (soil nitrogen transformation). Nominal concentrations were used. No statistical significant effects of the test item on nitrate content in soil were observed at day 28 up to a concentration of 100 mg Verdox/kg soil dw by Williams Multiple t-test Procedure. For concentrations of 320 mg and 1000 mg test substance/kg soil dw, the deviations to control were significant (Williams Multiple t-test Procedure). At day 28 differences in nitrogen production to the control were -30.25 %, 36.26%, 35.90% for 10-100 mg/kg soil, not significantly and not concentration related. At 320 and 1000 mg/kg dw the reduction was -99.64% and -73.94% for 320 mg and 1000 mg test substance/kg soil dw significantly though no clear dose relation. An EC10 could not be derived. The NOEC was determined to be 100 mg/kg soil dw based on nominal values.

Description of key information

The toxicity of the test substance for soil microflora was tested according to OECD TG 216 using nitrogen transformation in soil. The concentrations tested were 0, 10, 32, 100, 320 and 1000 mg/kg dw soil. The reference substance was sodium chloride. The soil used was abiologically active agricultural soil: Silty sand. The effect parameter was NO3-nitrogen production after 28 days exposure (soil nitrogen transformation). Nominal concentrations were used. No statistical significant effects of the test item on nitrate content in soil were observed at day 28 up to a concentration of 100 mg Verdox/kg soil dw by Williams Multiple t-test Procedure. For concentrations of 320 mg and 1000 mg test substance/kg soil dw, the deviations to control were significant (Williams Multiple t-test Procedure). At day 28 differences in nitrogen production to the control were -30.25 %, 36.26%, 35.90% for 10-100 mg/kg soil, not significantly and not concentration related. At 320 and 1000 mg/kg dw the reduction was -99.64% and -73.94% for 320 mg and 1000 mg test substance/kg soil dw significantly though no clear dose relation. An EC10 could not be derived. The NOEC was determined to be 100 mg/kg soil dw based on nominal values.

Key value for chemical safety assessment

Long-term EC10 or NOEC for soil microorganisms:

100 mg/kg soil dw