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Ecotoxicological information

Toxicity to soil macroorganisms except arthropods

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Reference
Endpoint:
toxicity to soil macroorganisms except arthropods: long-term
Type of information:
experimental study
Adequacy of study:
key study
Study period:
11 Apr - 11 Jun 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 222 (Earthworm Reproduction Test (Eisenia fetida/Eisenia andrei))
Version / remarks:
2016
Deviations:
yes
Remarks:
see "Any other information on material and method incl. tables"
GLP compliance:
yes (incl. certificate)
Remarks:
The Department of Health of the Government of the United Kingdom
Analytical monitoring:
no
Vehicle:
no
Details on preparation and application of test substrate:
- Method of mixing into soil: test item treatments were prepared by mixing the different weights of test item into 10 g dry quartz sand (see table 1 "Any other information on material and methods incl tables"): The volume required to achieve 50% of the maximum water holding capacity was calculated as 326.71 mL water/2200 g dry ISO earthworm soil which was added after the test item in sand had been mixed into a 2190 g dry weight equivalent of moist soil. For the water control 623.67 mL RO water was mixed into a 4180.9 g dry weight equivalent of moist soil to which 19.1 g dry sand had been added to bring the soil to 50% of the maximum water holding capacity. The moist soil was mixed using a hand held electric mixer.
- Controls: soil and water
Test organisms (species):
Eisenia fetida
Animal group:
annelids
Details on test organisms:
TEST ORGANISM
- Common name: earthworm
- Source: Earthworms were purchased from a reputable supplier; details are recorded only in the raw data to maintain supplier confidentiality
- Weight at test initiation: Selection of adult worms for the reproduction study was based primarily on individual weights falling within the specified weight range of 300 - 600 mg at the start of the treatment period
- Food: dried rabbit manure was used as food

ACCLIMATION
- Acclimation period: 24 h
- Acclimation conditions: same as test
Study type:
laboratory study
Substrate type:
artificial soil
Limit test:
no
Total exposure duration:
56 d
Test temperature:
19.3 – 21.6 °C
pH:
pH values are summarized within table 1 in section "Any other information on results incl. tabels"
Moisture:
18.52%
Details on test conditions:
TEST SYSTEM
- Test container: plastic containers 11 x 17 x 5 cm with tight fitting lid
- Amount of soil or substrate: ca. 666.43 g of soil (moistened to 50% of the maximum water holding capacity)
- No. of organisms per container (treatment): 10
- No. of replicates per treatment group: 4
- No. of replicates per control: 8

SOURCE AND PROPERTIES OF SUBSTRATE
- Geographic location: artificial soil was used (according to OECD 207)
- % sand: 70% (w/w)
- % peat: 10% (w/w)
- % clay: 10% (w/w)
- pH: was adjusted to 6.0 ± 0.5 using calcium carbonate (approximately pH 6.4 prior to treatment)
- Maximum water holding capacity (in % dry weigth): 66.57%
- Pretreatment of soil: initial moisture content was determined as 18.52%, no premoistening was required
- Others: Additional water was added weekly to bring the water content up to the original starting weight.

OTHER TEST CONDITIONS
- Photoperiod: 16-hour light: 8-hour dark
- Light intensity: 412 - 738 lux

EFFECT PARAMETERS MEASURED: Adult worms were removed from soil after 4 weeks after treatment and the juvenile worms reared for a further 4 weeks. Mortality was assumed when worms did not move when prodded and was measured after 4 weeks. Abnormal behavior, weight and observed symptoms were also determined. Number of surviving juvenile worms was determined after 56 days.

VEHICLE CONTROL PERFORMED: no

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 1.8
- Range finding study: no range-finding test was performed
Nominal and measured concentrations:
control, 16.3, 29.4, 52.9, 95.3, 171.5, 308.6, 555.6, and 1000 mg/kg dry soil
Reference substance (positive control):
yes
Remarks:
Mascot Systemic (active ingredient carbendazim)
Duration:
28 d
Dose descriptor:
LC50
Effect conc.:
> 1 000 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: parental 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:
mortality
Remarks on result:
other: parental mortality
Duration:
28 d
Dose descriptor:
LC50
Effect conc.:
> 1 000 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: body weight
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: body weight
Duration:
56 d
Dose descriptor:
EC50
Effect conc.:
> 1 000 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: number of offspring
Duration:
56 d
Dose descriptor:
NOEC
Effect conc.:
1 000 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: number of offspring
Details on results:
- Mortality at end of exposure period: Mortality in the test item treatments is not significant
- Mortality in the control: 2.5%
- Mortality in the toxic control: 7.5%
- Changes in body weight of live adults at end of exposure period: The adjusted mean bodyweights on Day 28 at rates of 16.3, 29.4, 52.9, 95.3, 171.5, 308.6, 555.6 and 1000 mg/kg dry soil were 469, 497, 477, 528, 541, 534, 531 and 540 mg respectively compared to 486 mg in the water control.
- No. of offspring produced: mean number of juveniles produced at rates of 16.3, 29.4, 52.9, 95.3, 171.5, 308.6, 555.6 and 1000 mg/kg dry soil was 154, 173, 149, 165, 168, 155, 151 and 159 respectively compared to 163 in the water control.
Results with reference substance (positive control):
For the toxic reference the prepared carbendazim solution (500 mL) was mixed into a 4180.9 g dry weight equivalent of moist soil to which 19.1 g dry sand had been added. An additional 123.67 mL RO water was also mixed in to achieve a soil concentration of 5 mg a.i./kg dry soil and 50% of the maximum water holding capacity.
Reported statistics and error estimates:
Statistical analysis was carried out using SAS 9.1.3 (SAS Institute 2002).

Biological results:

Health and Mortality

Adult mortality of 0, 12.5, 0, 17.5, 17.5, 15.0, 15.0 and 17.5% was recorded at rates of 16.3, 29.4, 52.9, 95.3, 171.5, 308.6, 555.6, and 1000 mg/kg dry soil respectively, compared to 2.5% control mortality (corrected mortality was 0, 10.3, 0, 15.4, 15.4, 12.8, 12.8 and 15.4% respectively). Adult mortality of 7.5% was recorded in the toxic reference treatment. The mortality in the test item treatments is not considered to be biologically significant, but rather due to low moisture content in the test chambers.

Body weight

There was no statistically significant impact on adult bodyweight at any test item treatment rate. The adjusted mean bodyweights on Day 28 at rates of 16.3, 29.4, 52.9, 95.3, 171.5, 308.6, 555.6 and 1000 mg/kg dry soil were 469, 497, 477, 528, 541, 534, 531 and 540 mg respectively compared to 486 mg in the water control. The adjusted mean bodyweight in the Mascot Systemic treated group was 300 mg, significantly lower than the water control group (p<0.001***), with a reduction of 25.7% in adjusted mean bodyweights.

Juvenile Worms

There was no statistically significant reduction in the number of juveniles produced at any test item treatment rate of up to and including 1000 mg/kg. The mean number of juveniles produced at rates of 16.3, 29.4, 52.9, 95.3, 171.5, 308.6, 555.6 and 1000 mg/kg dry soil was 154, 173, 149, 165, 168, 155, 151 and 159 respectively compared to 163 in the water control. No juveniles were produced in the Mascot Systemic treatment.

Table 1: pH value of the control and each treatment rate at the study start and completion.

Time (Days)

Untreated

Water control

Test item (mg/kg dry soil)

Mascot Systemic (5 mg a.i./kg dry soil)

 

 

 

16.3

29.4

52.9

95.3

171.5

308.6

555.6

1000

 

0

6.4

6.4

6.3

6.2

6.2

6.2

6.2

6.2

6.2

6.2

6.2

56

N/a

6.3

5.9

6.1

6.1

5.9

5.9

6.0

5.9

6.0

6.2

Validity criteria fulfilled:
yes

Description of key information

EC50 (56 d) > 1000 mg test item/kg dry weight soil (reproduction, Eisenia fetida, OECD 222)

NOEC (56 d) 1000 mg test item/kg dry weight soil (reproduction, Eisenia fetida, OECD 222)

EC50 (28 d) > 1000 mg test item/kg dry weight soil (mortality and body weight, Eisenia fetida, OECD 222)

NOEC (28 d) 1000 mg test item/kg dry weight soil (mortality and body weight, Eisenia fetida, OECD 222)

Key value for chemical safety assessment

Additional information

One experimental study is available investigating the toxicological effects of the test item (CAS 10094-45-8) to earthworms (ECT, 2017). The study was performed according to OECD guideline 222 under GLP conditions. Adult Eisenia fetida (4 x 10 animals per concentration, the fresh weight was between 300 and 600 mg) were exposed for 28 days in an artificial soil to the nominal concentrations of 16.3, 29.4, 52.9, 95.3, 171.5, 308.6, 555.6 and 1000 mg/kg dry soil. After 28 d adult worms were removed from the soil and the juvenile worms reared for a further four weeks.

The artificial soil comprised 10% peat, 20% kaolin clay and 70% industrial quartz sand. The parental LC50 was determined to be greater than 1000 mg/kg dry soil, the highest rate tested. A treatment related NOEC of 1000 mg/kg dry soil was achieved. The EC50 for the number of juveniles on Day 56 was determined to be >1000 mg/kg dry soil and a NOEC of 1000 mg/kg dry soil was achieved.