Ethyl 3-[[bis(1-methylethoxy)phosphinothioyl]thio]propionate

Toxicity to soil macroorganisms except arthropods

Link to relevant study record(s)

Reference

Endpoint:

toxicity to soil macroorganisms except arthropods: long-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 222 (Earthworm Reproduction Test (Eisenia fetida/Eisenia andrei))

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

yes

Remarks:

Acetone, which is later evaporated

Details on preparation and application of test substrate:

The earthworms were tested in an artificial soil. The composition of this soil was based on OECD Guideline No. 222 (the percentages refer to the dry weight).
26.6 kg quartz sand (73.8 % of total substrate mass) Supplier: Gebrüder Willersinn GmbH, 67071 Ludwigshafen, Germany
7.6 kg kaolin clay (21.1 % of total substrate mass) Supplier: Co. Bassermann minerals GmbH, 68169 Mannheim, Germany
1.8 kg sphagnum peat (5.0 % of total substrate mass), finely grounded. Supplier: Raiffeisen Mannheim eG, 68307 Mannheim, Germany
58.0 g CaCO3, p.A. (0.2 % of total substrate mass) Supplier: Merck
Total mass of the test substrate: 36.058 kg
Water holding capacity: 41.3 g/100g Dw (mean value)

The availability of lipophilic test item (ingredients) in soil and therefore their toxicity to earthworms depends on the organic matter content of the soil. For chemicals with logKow >2, adsorption is expected to be linearly related to soil organic matter content.
With respect to the properties of the test item (log Kow >2) 5 % instead of 10 % peat were used, considering the influence on bioavailability (OECD 222 and EPPO 2003).

The water solubility is not enough to prepare a sufficient stock solution with deionized water.
Application of the test substance: dissolved in acetone. The amount of 12500.5 mg test substance was weighed into a 50 mL volumetric flask.
The test substance was dissolved by addition of acetone as solvent. The solution was filled up to the mark afterwards. The test substance was completely dissolved. The solution was colourless and clear.

The required aliquots of the stock solution were added to 25 g quartz sand (10 g quartz sand/kg dry weight). The mixture was blended thoroughly and the organic solvent was removed by evaporation afterwards. No odour of the organic solvent was noticeable.
The required amounts of artificial soil were weighed into a mixing bowl. The test substance / quartz sand mixtures were added and thoroughly mixed with the soil. Amounts of deionized water were dosed in order to adjust the water content to about 50% WHCmax.. and mixed once again. The test mixtures were distributed to the test units.

Each replicate container was filled with about 664 g of the prepared test mixture (corresponding to about 550 g Dw artificial soil) to a layer of about 3.5 cm and a corresponding surface area of about 170 cm2.

Test organisms (species):

Eisenia fetida

Animal group:

annelids

Details on test organisms:

TEST ORGANISM
- Source: synchronized breeding culture at ECT Oekotoxikologie GmbH since 1994 (originally delivered by Co. Landenberger (Schoemberg, Germany)
- Age at test initiation: adult worms with clitellum, at least 2 months but less than 1 year. age differed not more than 4 weeks
- Weight at test initiation (mean and range, SD): 251-597mg

ACCLIMATION
- Acclimation period: overnight under permanent light before test start: 3 days after delivery worms were removed from transport box to a box filled with approx. 1kg freshly prepared test substrate for about 24 hours. Water content ca. 50% WHCmax.
- Acclimation conditions (same as test): yes

Study type:

laboratory study

Substrate type:

artificial soil

Limit test:

no

Total exposure duration:

56 d

Test temperature:

19.6° C – 20.9° C
In a separate vessel filled with test substrate two times per week during the exposure time with an electronic thermometer.

pH:

5.7-6.3
About 6 g wet test substrates were weighed in a beaker. Then 25 mL 0.01molar Calcium chloride solution was added. These mixtures were stirred for 5 minutes and rested for 2 hours. After shaking the pH value was measured in the settling samples.

Moisture:

16.2-21.0%
About 10-15 g artificial soil was weighed in a tared crucible. The soil samples from start of exposure were dried overnight and the soil samples from end of exposure dried for two days in a drying cabinet at 105°C. The content of water was calculated.

Details on test conditions:

TEST SYSTEM
- Test container (material, size): Plastic dishes with a volume of about 1.0 L, dimensions 11×15.5×6 [cm] with transparent and punctured lid (11x15.5x6 cm), inert and non-oxci plastic
- Amount of soil or substrate: ca. 664g artificial soil (wet weight)
- No. of organisms per container (treatment): 10
- No. of replicates: 8 replicates for the solvent control and 4 replicates for the control and for each test and reference substance concentration


PROPERTIES OF SUBSTRATE (if soil)
- Organic carbon (%): 5

OTHER TEST CONDITIONS
- Photoperiod and light intensity: Light/day cycles of 16:8 hours, over the exposure period, 607 Lux, (mean of 5 single measurements: 716, 518, 584, 625 and 592 [Lux]), once at start of adaption: 752 Lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
number and biomass at start of expore and after 28 days, consumption of food, mporphological and behavioral changes, mortality of adult worms after 28 days, number of juvenile worms at the end of exposure

VEHICLE CONTROL PERFORMED: yes

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2

FEEDING:
finely ground cow manure (free of growth promoters, nematicides or similar veterinary pharmaceuticals, provided by Jesus Bruderschaft e.V. Gnadenthal, Hünfelden, Germany).
An amount of 5 g moistened with about 5-6 mL deionized water was spread on the test substrate surface of each test container. If food remained unconsumed, the ration was reduced on demand. After removing the adults on day 28 further 5 g of food moistened with about 5-6 mL deionized water was mixed with the test substrate of each test vessel.

Nominal and measured concentrations:

control, solvent control, 62.5, 125, 250, 500, 1000mg/kg dw

Reference substance (positive control):

yes

Remarks:

Carbendazim, CAS 10605-21-7

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:

mortality

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:

other: biomass

Key result

Duration:

56 d

Dose descriptor:

NOEC

Effect conc.:

62.5 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Key result

Duration:

56 d

Dose descriptor:

EC10

Effect conc.:

101 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks on result:

other: confidence limits (LCL, UCL)

Remarks:

80.3-126

Duration:

56 d

Dose descriptor:

EC50

Effect conc.:

208 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks on result:

other:

Remarks:

confidence limits (LCL, UCL) / 186-231

Details on results:

No mortality of adult worms was observed in the controls and at all replicates with test substance.
Statistical analysis show no significant difference (Williams Test one sided and Dunnett test one sided p ≤0.05) concerning the body weight change of individual adults over 28 days between the solvent control and all replicates of the tested test substance concentrations.

Observations:
Day 0: Introduction of the worms
At the highest test concentrations (500 and 1000mg/kg dw) adult worms did not submerge in the test substrate.
Day 1: 1 replicate 500mg/kg: The lid of the test container was not carefully closed. Seven worms escaped from the container on day of exposure to day1. Therefore, this container was not considered for the evaluation. However all other worms were submerged.

Results with reference substance (positive control):

0.1, 0.5, 1.0, 2.5 mg/kg dw (nominal concentrations)
EC10 1.09mg/kg dw
EC50 1.67 mg/kg dw
These observed effects are within the expected range from the test guideline (1-5 mg/kg carbendazim/kg soil (dw)) and hence acceptable sensitivity of the test system is assured.

Validity criteria fulfilled:

yes

Conclusions:

The results in this study are consistent with all validity criteria and the test is valid according to the test guideline of this study. No deviations from the test guidelines or other incidents occurred during the course of the reported test, which may have influenced the results.

Description of key information

Toxic effects have been observed in a study with soil macroorganisms. In a chronic study with earthworms adverse effects on reproduction occurred.

Key value for chemical safety assessment

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

101 mg/kg soil dw

Additional information

The toxicity to terrestrial macroorganisms was determined in a study according to OECD guideline No 222 and in compliance with GLP criteria.

Two 56-day reproduction tests with Eisenia fetida were performed. Test concentrations of 62.5, 125, 250, 500 and 1000 mg/kg d.w. (dry weight) were tested. The following endpoints were recorded:

·Biomass of adult animals: day 0 and 28

·Mortality of adult worms: day 28

·Reproduction: day 56

The test met the acceptability criteria prescribed by the study plan and were considered valid. Under the conditions of the present study, the substance did not reduce the reproduction of Eisenia fetida at a nominal concentration of 62.5 mg/kg d.w. after 56 days of exposure (NOEC).

The 56-day EC10 for reproduction was 101 mg/kg d.w. The ECx values are based on 5% organic carbon content. The 28-d NOEC for mortality and weight reduction was 1000 mg/kg d.w. All validity criteria were met.