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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:
11/04/2000 - 17/01/2001
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP, Guideline study
Qualifier:
according to guideline
Guideline:
ISO 11268-2 (Effects of Pollutants on Earthworms. 2. Determination of Effects on Reproduction)
Deviations:
no
Qualifier:
according to guideline
Guideline:
other: BBA Guideline Part VI, 2-2, 1994
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
no
Details on sampling:
Mortality and growth of the adults was determined 28 days after start of exposure.
Reproduction was determined 56 days after start of exposure.
Vehicle:
yes
Details on preparation and application of test substrate:
Artificial soil test substrate: Sphagnum peat: 10 %
Kaolinite clay: 20 %
Sand: 69 %
CaCO3: 0.3 %
Food: 1 %
Test mixture: The following nominal concentrations were tested: 0.08, 0.2, 0.5, 1.3, 3.2 and 8.0 mg/kg dry soil. A positive control with the reference item Derosal® (active ingredient 60 % Carbendazim) was tested at 4.2 mg/kg dry soil (corresponding to 2.5 mg carbendazim a.i./kg dry soil)
Size, volume and material of test container: Glass dish, 14 cm diameter, 7 cm high
Amount of artificial soil (kg)/ container: 527 g (corresponding to 500 g dry weight)
Nominal levels of test concentrations: 0.08, 0.2, 0.5, 1.3, 3.2 and 8.0 mg dinotefuran/kg dry soil
Number of replicates/concentration: 4
Number of earthworms/test concentration: 40
Number of earthworms/container: 10
Light source: Not reported
Test performed in closed vessels due to significant volatility of test substrate: No
Test organisms (species):
Eisenia fetida
Animal group:
annelids
Details on test organisms:
Species/strain: Eisenia fetida
Source of the initial stock: Blades Biological, Kent/London, TN8 7DX, UK
Culturing techniques: Not reported
Age/weight: age: 7 – 8 months; weight: 300 – 600 mg
Pre-treatment: Earthworms were acclimated for three days to the artificial soil and test temperature
Study type:
laboratory study
Substrate type:
artificial soil
Limit test:
no
Total exposure duration:
56 d
Post exposure observation period:
28 days
Test temperature:
19 – 22 °C
pH:
5.9 - 6.1 after 8 weeks
Moisture:
34 - 37% water content after 8 weeks
Details on test conditions:
Light intensity / photoperiod: 640 - 750 Lux, 16 hours light and 8 hours dark
Relevant degradation products: none
Nominal and measured concentrations:
Initial concentration of test substance: 0.08, 0.2, 0.5, 1.3, 3.2 and 8.0 mg/kg dry weight artificial soil
Reference substance (positive control):
yes
Remarks:
Carbendazim 2.5 mg/kg dry soil was tested as a positive control
Duration:
28 d
Dose descriptor:
LC50
Effect conc.:
5.1 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: 4.1 - 6.2 mg/kg.
Duration:
28 d
Dose descriptor:
EC50
Effect conc.:
1.2 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: for living offspring after 28 days of exposure, reproduced by adults within 28 days of exposure.
Remarks on result:
other: 0.6 - 2.3 mg/kg
Key result
Duration:
28 d
Dose descriptor:
NOEC
Effect conc.:
0.2 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Duration:
28 d
Dose descriptor:
LOEC
Effect conc.:
0.5 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Details on results:
After 28 days, the mortality rate of adult organism in the negative control was 2.5 %. Mortality in the treatment groups 0.08, 0.2, 0.5, 1.3 and 3.2 mg/kg dry soil did not exceed 7.5 %. At the highest test concentration (8.0 mg/kg) the mortality rate was 92.5 %.

The growth rate of adult earthworms in the control was 43 % throughout the 28-day adult exposure period.

The growth rates of adult earthworms in the 0.08 and 0.2 mg/kg treatment groups were 45 and 39 % throughout the 28-day adult exposure period respectively. The results of a Williams-test (one-sided, α = 0.05) showed no statistically significant difference when compared to the negative control.
The growth rates of adult earthworms in the 0.5, 1.3 and 3.2 mg/kg treatment groups were 24, 17, and 14 %throughout the 28-day adult exposure period. The results of a Williams-test (one-sided, α = 0.05) showed statistically significant difference to the negative control.

The growth rate of the three surviving earthworms in the 8.0 mg/kg treatment group was -31 % throughout the 28-day adult exposure period. The results of a Williams-test (one-sided, α = 0.05) showed statistically significant difference to the negative control.

The reproduction rate in the control was found to be 8.2 ± 2.2 (CV 27.5%) after the 28 day reproduction period.

The reproduction rates in the 0.08, 0.2 and 0.5 mg/kg treatment group were 8.5 ± 2.0 (CV 23.1), 7.6 ± 1.2 (CV 15.6) and 7.9 ± 1.5 (CV 18.7), respectively. The results of a Williams-test (one-sided, α = 0.05) showed no statistically significant difference to the negative control.

The reproduction rates in the 1.3 and 3.2 mg/kg treatment group were 2.9 ± 1.6 (CV 53.9) and 1.4 ± 1.3 (CV 92.6), respectively. The results of a Williams-test (one-sided, α = 0.05) showed statistically significant difference to the negative control.

In the highest treatment group (8.0 mg/kg), reproduction was completely inhibited.

Food consumption of adult earthworms was reduced in the higher treatment groups. Only visual inspections for food consumption were carried out, but a clear dose response in the reduction of food consumption was noticeable.

See Tables 1 to 3.
Results with reference substance (positive control):
See Tables 1 to 3.
Reported statistics and error estimates:
Mortality: The 28 day LC50 and its 95 % confidence intervals were calculated by Moving Average Interpolation

Growth rate: For each test vessel, the difference of the mean body wet weight of the surviving organisms between the start and the end of exposure was calculated. The mean growth rates of the surviving worms in the test item treatment groups were compared to the negative control and were statistically evaluated by means of a multiple Williams-test after a one-way analysis of variance (ANOVA). The mean growth rate in the positive control was compared to the negative control value and was statistically evaluated by means of a Student t-test.

Table 1: Mortality data: Number of living adult earthworms and % mortality after 28 days of exposure

Test concentration [mg/kg]1

Vessel No.

Numberofworms

Number of alivewormsafter 28 days

Sumofdead after 28 days

Mortality after 28 days(%)

control

1

10

10

1

2.5

2

10

10

3

10

9

4

10

10

0.08

1

10

10

0

0

2

10

10

3

10

10

4

10

10

0.2

1

10

10

0

0

2

10

10

3

10

10

4

10

10

0.5

1

10

10

0

0

2

10

10

3

10

10

4

10

10

1.3

1

10

10

1

2.5

2

10

9

3

10

10

4

10

10

3.2

1

10

8

3

7.5

2

10

10

3

10

9

4

10

10

8.0

1

10

0

37

92.5

2

10

0

3

10

3

4

10

0

positive control*

1

10

10

0

0

2

10

10

3

10

10

4

10

10

* Carbendazim 2.5 mg a.i./kg dry soil

1nominal

 

Table 2: Mean body wet weights of adult earthworms at the test start and after 28 days of exposure

Test concentration

Mean body weight at test start

Mean body weight after 28 days

Mean change

[mg/kg]

[mg]*

[mg]*

[mg]*

[%]

STAT#

control

424 (23)

605 (71)

181 (78)

43

-

0.08

429 (30)

623 (53)

194 (30)

45

n.s.

0.2

443 (42)

613 (38)

170 (24)

39

n.s.

0.5

419 (27)

519 (45)

100 (25)

24

s.

1.3

441 (26)

516 (46)

75 (34)

17

s.

3.2

447 (16)

511 (38)

64 (36)

14

s.

8.0

421 (19)

270**

- 124**

- 31

s.

positive control

424 (21)

596 (51)

172 (35)

40

n.s.

* mean over all four replicates (Standard Deviation)

** surviving earthworm only in one replicate, no SD calculated

# Statistical comparison of the changes in mean body weight of the treatments compared with the control

n.s. not statistically significant

s. statistically significant

 

Table3: Reproduction of earthworms

Test concentration

Juveniles

Reproduction rate (per surviving adult)

STAT#

[mg/kg]

Mean ± SD

Mean ± SD

CV (%)

% of control

 

control

80 ± 22

8.2 ± 2.2

27.5

100

-

0.08

85 ± 20

8.5 ± 2.0

23.1

104

n.s.

0.2

76 ± 12

7.6 ± 1.2

15.6

93

n.s.

0.5

79 ± 15

7.9 ± 1.5

18.7

96

n.s.

1.3

28 ± 15

2.9 ± 1.6

53.9

36

s.

3.2

13 ± 12

1.4 ± 1.3

92.6

17

s.

8.0

0 ± 0

0 ± 0

-

0

s.

positive control

27 ± 18

2.7 ± 1.8

67.1

33

s.

# Statistical comparison of the changes in mean body weight of the treatments compared with the control

n.s. not statistically significant

s. statistically significant

Validity criteria fulfilled:
yes
Conclusions:
The mortality of adult earthworm in the control was within the recommended range according the guidelines. The positive control carbendazim demonstrated the sensitivity of the test system and satisfying test conditions.

A clear dose response for mortality, growth and reproduction was demonstrated.

The overall NOEC was determined to be 0.2 mg/kg dry soil and the overall LOEC was determined to be 0.5 mg/kg dry soil.

Description of key information

The overall NOEC was determined to be 0.2 mg/kg dry soil and the overall LOEC was determined to be 0.5 mg/kg dry soil.

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for soil macroorganisms:
0.2 mg/kg soil dw

Additional information