2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one

Toxicity to soil macroorganisms except arthropods

Link to relevant study record(s)

Reference

Endpoint:

toxicity to soil macroorganisms except arthropods: short-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 207 (Earthworm, Acute Toxicity Tests)

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Details on preparation and application of test substrate:

- Method of mixing into soil (if used):
The corresponding amounts of the test item were weighed separately for each concentration using an analytical balance and fine quartz sand was added until a final net weight of 20 g was reached. After pulverizing with a mortar and pistil to reach a homogeneous distribution of the test item within the sand the mixture was added to artificial soil equivalent to 2030 g dry weight, resulting in the following nominal concentrations of the test item.
There were no significant deviations from the target concentration (< 5%). The control was treated with the same amount sand as the test item groups. While mixing the artificial soil in a laboratory mixer for approximately 5 minutes the soil of each treatment group was moistened with deionised water to achieve the required water content. Each group was treated in one batch and then split into 4 replicates.
The target concentrations were selected based on the non-GLP range finding test.

Test organisms (species):

Eisenia fetida

Animal group:

annelids

Details on test organisms:

TEST ORGANISM
- Common name: Earthworms
- Source: Bred under standardised conditions in IBACON laboratories in a breeding medium of cattle manure, peat, sand, calcium carbonate and straw, fed with cattle manure, stored at room temperature.
- Age at test initiation (mean and range, SD): Approximately 11 months, with clitellum
- Weight at test initiation (mean and range, SD): 300 to 600 mg

ACCLIMATION
1 day, in artificial soil, under test conditions

Study type:

laboratory study

Substrate type:

artificial soil

Limit test:

no

Total exposure duration:

14 d

Test temperature:

Maintained within the range of 18°C and 22°C

pH:

pH range at experimental start: 5.5
pH range at experimental end: 5.5

Moisture:

Water content:
At experimental start: 20.3% to 22.0% (49.5% to 53.7% of the maximum water holding capacity).
At experimental end: 20.7% to 21.2% (50.4% to 51.8% of the maximum water holding capacity)

Details on test conditions:

TEST SYSTEM
- Test container (material, size): Glass jars (1 L), loosely covered by glass-lids to enable exchange of air and to minimise evaporation, filled with approximately 500 g (dry weight equivalent) artificial soil
- No. of organisms per container (treatment): 40
- No. of replicates per treatment group: 4
- No. of replicates per control: 4

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
Artificial soil was prepared based on OECD 207 but with reduced organic matter content before the study started and stored until use in a closed plastic container.
Ingredients:
• 5% Sphagnum-peat, air-dried and finely ground (2 mm); (Floragard, Vertriebs GmbH für Gartenbau, 26138 Oldenburg, Germany, manufactured according to DIN 11540)
• 20% Kaolin clay (Erbslöh, 65558 Lohrheim, Germany)
• approximately 0.2% calcium carbonate (CaCO3) added to adjust pH to 6.0 ± 0.5 (Merck, 64293 Darmstadt, Germany)
• approximately 74.8% fine quartz-sand (F34) containing more than 50% by mass of particle size 0.05 mm to 0.2 mm; (Quarzwerke Frechen, Postfach 1780, 50207 Frechen, Germany)
At CAL GmbH & Co. KG Darmstadt, the total organic carbon content (TOC) of the soil was determined to be 1.42 % (w/w), (method: DIN EN 13137). According to Nelson and Sommers (1996) this value corresponds to a percentage of total organic matter content (TOM) of 2.44 % (w/w).
According to OECD 222 and EPPO 2003, 5% of peat was used in the artificial soil considering the influence of the test item on bioavailability.

OTHER TEST CONDITIONS
- Photoperiod: Continuous
- Light intensity: Maintained within the range of 400 and 800 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Mortality:Number of dead earthworms at days 7 and 14 after application
Behavioural Abnormalities: Number of affected earthworms (e.g. not burrowing into the soil, lack of movement, rigidity, etc.) after introduction, on day 7 and 14
Mean Body Weights: Per test container determined at start (day 0) and 14 days after application, using same washing procedures as at experimental start but worms were weighed in groups at experimental end.

VEHICLE CONTROL PERFORMED: no vehicle used

TEST CONCENTRATIONS
- Range finding study: The target concentrations were selected based on the non-GLP range finding test.
- Test concentrations: 10, 32, 100, 320, 1000 mg/kg artificial soil dry weight

Nominal and measured concentrations:

Nominal: 10, 32, 100, 320, 1000 mg/kg soil

Reference substance (positive control):

no

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

> 1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

320 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: mortality and biomass

Details on results:

- Mortality:
No mortality was observed after 7 days of exposure.
After 14 days of exposure no mortality was observed up to and including the concentration of 320 mg test item/kg soil. At 1000 mg test item/kg soil a mortality of 25% was observed which was statistically significant when compared to the control (Fisher´s Exact Test, one-sided greater, α = 0.05).
According to these results the LC50 to Eisenia fetida after 14 days in artificial soil was determined to be greater than 1000 mg test item/kg soil.
- Body Weight Changes:
The body weight changes of the earthworms were not statistically significantly different compared to the control up to and including the concentration of 320 mg test item/kg soil. At the concentration of 1000 mg test item/kg soil a statistically significant decrease of body weights was observed (Williams t-test, two sided, α = 0.05).
Therefore, the Lowest Observed Effect Concentration (LOEC) was determined to be 1000 mg test item/kg soil and the No Observed Effect Concentration (NOEC) was determined to be 320 mg test item/kg soil.
- Behavioural Abnormalities:
At the concentrations 1000 mg test item/kg soil worms showed signs of agitation after 14 days exposure. No additional behavioural effects were observed.

Validity criteria fulfilled:

yes

Conclusions:

In a 14-d toxicity study to earthworms (Eisenia fetida), the LC50 was determined to be greater than 1000 mg test item/kg soil. The NOEC related to mortality and biomass was determined to be 320 mg/kg soil.

Description of key information

The study provided was conducted to recognised testing guidelines and with GLP certification.

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for soil macroorganisms:

320 mg/kg soil dw

Additional information

The acute toxicity on earthworms (Eisenia fetida) of the test item was investigated in a GLP guideline study according to OECD 207 (IBACON 2013). After 14 days of exposure the LC50 was determined to be > 1000 mg/kg dry weight. The NOEC for mortality and biomass was determined to be 320 mg/kg soil after 14 d.

Information concerning long-term effects on the toxicity to soil macroorganisms is not available for the test substance. The test substance is not supposed to be directly applied to soil and an indirect exposure is unlikely since the log Koc is below 3 and the substance has no cationic properties. Both parameters indicate a low adsorption potential of the test substance. Therefore, binding to sewage sludge is unlikely and as a consequence a transfer to the soil compartment is not expected.

Additionally, an environmental exposure assessment was performed in order to determine possible risks of the test compound to the environment. According to the results of the exposure assessment, all the relevant uses of the test substance are considered to be safe with a Risk Characterization Ratio below 1. Hence, further tests on long-term effects to soil macroorganisms are not provided.