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Short-term toxicity to aquatic invertebrates

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Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
22/11/1999 - 10/02/2000
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP, Guideline study
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 850.1010 (Aquatic Invertebrate Acute Toxicity Test, Freshwater Daphnids)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
At 0-hour and 48 hour
Vehicle:
no
Test organisms (species):
Daphnia magna
Details on test organisms:
Strain: Daphnia magna Straus
Age: 6-24 hours old
Breeding method: The Daphnids from the clone line were bred in the laboratories of RCC in reconstituted water under identical conditions as in the tests.
Kind of food: Not reported
Amount of food: Not reported
Feeding frequency: Not reported
Pretreatment: No
Feeding of animals during test: No
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 h
Post exposure observation period:
none
Hardness:
1.25 mmol/L (= 125 mg/L) as CaCO3
Test temperature:
20 – 21 ºC
pH:
7.7 – 7.8
Dissolved oxygen:
8.7 mg/L
Salinity:
not applicable
Nominal and measured concentrations:
See table below: Nominal and measured concentrations
Reference substance (positive control):
no
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
>= 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
The analytically determined mean test item concentrations at the start and the end of the test were 97% of the nominal value. The test item MTI-446 was stable under the test conditions during the test period of 48 hours. Therefore all results are reported as nominal test concentrations. In the control (0 mg/L) and the test item concentration of 1000 mg/L, no immobilized or dead test organisms or other signs of intoxication were determined during the entire test period (48 hours).

The 48-hour NOEC and the 48-hour EC0 of dinotefuran to Daphnia magna were determined to be ≥ 1000 mg/L. The 48-hour EC50 and the 48-hour EC100 were >1000 mg/L.

No remarkable observations were made concerning the appearance of the test medium. It was a clear solution throughout the whole test duration. At the beginning and the end of the test period, the oxygen concentrations in the test medium and the control was 8.7 mg/L and the pH-values ranged from pH 7.7 - 7.8.
The EC50 and EC100 values (with 95% C.I.) could not be calculated due to insufficient immobility. The NOEC and LOEC were determined visually.

See Tables 1 and Table 2.
Results with reference substance (positive control):
Not applicable
Reported statistics and error estimates:
The NOEC and EC0 were determined directly from the raw data.

Nominal and measured concentrations:

Nominal test

Concentration (mg/L)

Sample

(h)

Measured Concentration

(mg/L)

1000

0

0

965.8

974.8

48

48

964.7

967.8

Table 1:           Immobility of dinotefuran on Daphnia magna

Treatment

mg/L

(Nominal conc.)

Observation period

24 hours

48 hours

endpoint

% affected

endpoint

% affected

Dilution water Control

Immobile

0

Immobile

0

Solvent Control

N/A

N/A

N/A

N/A

Positive Control, if used

N/A

N/A

N/A

N/A

968.3 (1000)

Immobile

0

Immobile

0

 

Table 2:          Effect data of dinotefuran on Daphnia magna

Treatment

mg/L

(Nominal conc.)

Observation period

24 hours

48 hours

NOEC, mg/L

≥1000

≥1000

LOEC, mg/L

>1000

>1000

EC50(with 95% C.I.), mg/L

>1000

>1000

 

Validity criteria fulfilled:
yes
Conclusions:
The 48-hour EC50 was > 1000 mg/L, which categorizes dinotefuran as nontoxic to the water flea (Daphnia magna) on an acute toxicity basis. The 48-hour NOEC and LOEC levels were ≥ 1000 and > 1000 mg/L, respectively.
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
17 February 2000 - 04 July 2000
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
comparable to guideline study
Justification for type of information:
The aquatic species shown to be most sensitive to dinotefuran was the chironomid
(Chironomus riparius) following both acute and chronic exposure. The acute 48 h LC50 was
72.1 μg/l and the 27 d NOEC was 2.54 μg/l. These results are consistent with the opinion
that daphnids (the most usual aquatic invertebrate tested) are not as susceptible to
neonicotinoid insecticides as other invertebrates. Information on endpoints for other
neonicotinoids (e.g. imidacloprid, clothianidin) is available in the EFSA conclusions/Review
Reason / purpose:
reference to other study
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Version / remarks:
The study was conducted wit the larvae of the midge Chironomus riparius
Qualifier:
equivalent or similar to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Version / remarks:
The study was conducted wit the larvae of the midge Chironomus riparius
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
After 0 and 48 hours
Vehicle:
no
Test organisms (species):
other aquatic arthropod: Chironomus riparius
Details on test organisms:
The study was performed with first-instar larvae of the midge Chironomus riparius. The midge culture was originally supplied by Novartis Crop Protection AG, CH-4002 Basel, Switzerland. Chironomus riparius was bred in the laboratories of RCC under similar temperature and light conditions as in the test, and in the same kind of test water as used in the test.
Test type:
static
Water media type:
other: reconstituted water M7
Limit test:
no
Total exposure duration:
48 h
Hardness:
250 mg/L CaCO3
Test temperature:
20°C
pH:
7.9 - 8.8
Dissolved oxygen:
8.8 mg/L
Nominal and measured concentrations:
nominal: 2.2, 4.6, 10, 22, 46 and 100 µg/L
measured: n.a., n.a., n.a., 22, 43, 93 µg/L
Key result
Duration:
48 h
Dose descriptor:
LC50
Effect conc.:
72.1 µg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
After the test period of 24 hours no mortality of the test organisms was determined in the control and all test media up to and including the highest concentration of 100 µg/L. However, at the highest test concentration all larvae showed convulsions and unusual body movements (clearly different to the larvae in the control). At the lower test concentrations of 2.2 - 46 µg/L this sign of intoxication was not determined. Thus, the 24-hour LC50 of the test item was >100 µg/I, the 24-hour LCO was at least 100 µg/L. After 48 hours of exposure the toxicity of the test item to the larvae of Chironomus riparius had increased: Now the larvae at 46 µg/I showed convulsions and unusual body movements. At the highest test concentration of 100 µg/L 17 larvae were dead (corresponding to a mortality rate of 85%). The remaining three alive larvae showed convulsions and unusual body movements, and thus probably would have died after short time. In the range-finding tests even 100% mortality was recorded at 100 µg/L. The 48-hour LC50 was calculated to be 72.1 µg/L with 95% confidence limits from 64.5 to 80.6 µg/L. The 48-hour LCO of MTI-446 was 46 µg/L. The 48-hour NOEC (highest concentration tested without toxic effects after 48 hours) was 22 µg/L, since no mortality and no signs of intoxication were observed at the test organisms up to and including this test concentration. The lowest test concentration with toxic effects after 48 hours (48-hour LOEC) was 46 µg/L. The 48-hour LC100 was approximately 100 µg/L. Thus, the concentration-effect relationship of the acute toxicity of MTI-446 to first-instar larvae of Chironomus riparius was rather steep. No remarkable observations were made concerning the appearance of the test media. All test media were clear solutions throughout the whole test duration. At the beginning and the end of the test period, the oxygen concentrations in the test media and the control were at least 8.8 mg/L. The pH-values ranged from pH 7.9 to 8.0

Nominal concentration [µg/L]

No larvae introduced

No. dead larvae

% mortality after 24 h

% mortality after 48 h

24 h

48 h

Control

20

0

0

0

0

2.2

20

0

0

0

0

4.6

20

0

0

0

0

10

20

0

0

0

0

22

20

0

0

0

0

46

20

0

0*

0

0"

100

20

0*

17**

0*

85**

* No mortality, but all larvae showed convulsions and unusual body movements (clearly different compared to the larvae in the control)

** The remaining three alive larvae showed convulsions and unusual body movements.

Validity criteria fulfilled:
yes
Remarks:
no mortality in the control
Executive summary:

The acute toxicity of the test item MTI-446 to first-instar larvae of the midgeChironomus ripariuswas determined in a 48-hour static test. The test item was dissolved in water, and the larvae were introduced into these test media. The survival rate of the larvae and symptoms of intoxication were recorded during the test period. No sediment was added in this acute test since otherwise the small larvae, dwelt in sediment cannot be observed.

The nominal test item concentrations tested were 2.2, 4.6, 10, 22, 46 and 100 pg/I, and in parallel a control.

The analytically determined concentrations of MTI-446 in the test media from the start and the end of the test varied in the range from 92 to 98% of the nominal values. In the test media MTI-446 was sufficiently stable during the test period of 48 hours. Therefore, all reported biological results are related to the nominal concentrations of the test item.

Description of key information

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
72.1 µg/L

Additional information