A mixture of cis- and trans-cyclohexadec-8-en-1-one

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:

2021-09-08 to 2021-10-06

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:

2000

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Test organisms (inoculum):

soil

Total exposure duration:

28 d

Test temperature:

18.8 - 21.5 °C

Moisture:

day 0: 42.9-43.9% of MWHC (Maximum Water Holding Capacity);
day 28: 43.0-46.1% of MWHC (Maximum Water Holding Capacity);

Organic carbon content (% dry weight):

0.656

Nitrogen content (% dry weight):

26.1

Details on test conditions:

TEST SYSTEM
- Test container (type, material, size): Plastic boxes (volume 1.0 L, food grade) with perforated tops to enable gas exchange.
- Amount of soil: 400 g DW
- No. of replicates per concentration: 3
- No. of replicates per control: 3

SOIL INCUBATION
- Method: bulk / series of individual subsamples

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- A field fresh, silty sand soil (LUFA standard soil 2.3) was used in the study.
- Soil texture: silty sand
- % sand: 57 %
- % silt: 35%
- % clay: 8
- pH (in water): 6.2
- Initial nitrate concentration for nitrogen transformation test (mg nitrate/kg dry weight): 25.4
- Maximum water holding capacity (in % dry weigth): 35.5
- Cation exchange capacity (meq /100 g): 6.0
- Storage (condition, duration): The soil was stored for 61 days (2021-06-18 to 2021-08-17) in the dark at 4 - 6 °C in a climatic room. Subsequently, the soil was
pre-incubated at room temperature (ca. 20 °C) for 22 days (2021-08-17 to 2021-09-08) to adapt the micro-organisms to test conditions before the start of the study.
- Initial microbial biomass as % of total organic C: 2.22

RANGE-FINDING STUDY
- Test concentrations: 10-100-1000 mg/kg DW
- Results used to determine the conditions for the definitive study: Yes

Nominal and measured concentrations:

Nominal concentrations: 1000 - 316 - 100 - 31.6 - 10 mg/kg soil dry weight

Reference substance (positive control):

yes

Remarks:

Cyanoguanidine

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

10 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: The Nitrate-N content

Key result

Duration:

28 d

Dose descriptor:

EC10

Effect conc.:

37 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: The Nitrate-N content

Key result

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

286 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: The Nitrate-N content

Details on results:

See below

Results with reference substance (positive control):

- Results with reference substance valid? Yes

Inhibition of Nitrate-N Content in Soil Containing test item, Relative to the Control

Nitrate-N Content
Test item concentration	Inhibition [%] compared to control
[mg/kg DW]	d 0	d 7	d 14	d 28
10	4	10	1	1
31.6	15	16	17	14
100	12	35	24	21
316	11	100	71	53
1000	4	100	100	100

 

Inhibition of Nitrate-N Formation Rates in Soil Containing test item, Relative to the Control:

Nitrate-N Formation Rate
Test item concentration	Inhibition [%] compared to control
[mg/kg DW]	d 0-7	d 0-14	d 0-28
10	35	-5	-1
31.6	19	21	12
100	n.d.	54	32
316	n.d.	n.d.	n.d.
1000	n.d.	n.d.	n.d.

n.d. = not determinable due to negative formation rates in the replicates

Validity criteria fulfilled:

yes

Remarks:

Variation between control replicates was < 15 % at days 0, 7, 14 and 28 for the determination of inorganic nitrogen (nitrate-N content).

Conclusions:

The toxicity of the test item to soil microorganisms was determined and resulted in an EC10 value of 37 mg/kg DW and EC50 value of 286 mg/kg DW, respectively.

Executive summary:

The toxicity of the test item to soil microorganisms was determined according to OECD Guideline 216 (2000) and GLP. Based on the result from a preliminary study, the test item was applied via quartz sand at concentrations of 1000 - 316 - 100 - 31.6 - 10 mg/kg soil dry weight (factor √10). Untreated field soil, adjusted to a moisture content corresponding to nominally 45 % of its maximum water holding capacity and mixed with a source of organic nitrogen (lucerne-greengrass-meal), was tested as the control under the same test conditions as the test item replicates. Plastic boxes (volume 1.0 L) with perforated tops to enable gas exchange filled with 400 g soil dry weight were used as test vessels.The effects of the test item on nitrogen transformation by soil microflora were determined by comparing rates of formation of the final transformation product, nitrate-nitrogen (NO₃^--N), in soil treated with the test item against the rate observed in the untreated control. Under the test conditions, the EC10 and EC50 values were determined to be 37 mg/kg DW and 286 mg/kg DW, respectively.

Description of key information

A study on the toxicity of the item to soil microorganisms is available. The test was performed according to OECD Guideline 216 (2000) and GLP. Based on the result from a preliminary study, the test item was applied via quartz sand at concentrations of 1000 - 316 - 100 - 31.6 - 10 mg/kg soil dry weight (factor √10). Untreated field soil, adjusted to a moisture content corresponding to nominally 45 % of its maximum water holding capacity and mixed with a source of organic nitrogen (lucerne-greengrass-meal), was tested as the control under the same test conditions as the test item replicates. Plastic boxes (volume 1.0 L) with perforated tops to enable gas exchange filled with 400 g soil dry weight were used as test vessels.The effects of the test item on nitrogen transformation by soil microflora were determined by comparing rates of formation of the final transformation product, nitrate-nitrogen (NO₃^--N), in soil treated with the test item against the rate observed in the untreated control. Under the test conditions, the EC10 and EC50 values were determined to be 37 mg/kg DW and 286 mg/kg DW, respectively.

Key value for chemical safety assessment

Short-term EC50 for soil microorganisms:

286 mg/kg soil dw

Long-term EC10 or NOEC for soil microorganisms:

37 mg/kg soil dw