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Short-term toxicity to aquatic invertebrates

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Reference
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2017-07-05 - 2017-11-01
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study conducted to GLP in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results.
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Version / remarks:
Also used for preparation of the test substance: Guidance document on aquatic toxicity testing of difficult substances and mixtures, OECD series on testing and assessment number 23, 2000.
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Guidance document on aquatic toxicity testing of difficult substances and mixtures, OECD series on testing and assessment number 23, 2000

Preparation of test solutions started with a loading rate of 100 mg/L applying a one day period of magnetic stirring to ensure maximum dissolution of the test item in medium. The obtained mixture was allowed to settle for 13 minutes. Thereafter, the aqueous Saturated Solution (SS) was collected by means of siphoning and used as the highest test concentration. Lower test concentrations were prepared by subsequent dilutions of the SS in test medium. All test solutions were clear and colorless at the end of the preparation procedure.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Water flea
- Strain/clone: Daphnia magna (Crustacea, Cladocera) (Straus, 1820), at least third generation, obtained by a cyclical parthenogenesis under specified breeding conditions.
- Source: Charles River Laboratories, In-house laboratory culture with a known history
- Age of parental stock (mean and range, SD): Maximum age of the cultures 4 weeks
- Feeding during test: No feeding
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Test temperature:
18-22 °C, constant within 2 °C
pH:
pH 7.7-7.9
Dissolved oxygen:
8.9-7.8 mg/L
Nominal and measured concentrations:
0.46%, 1.0%, 2.2%, 4.6%, 10% and 22% of a SS prepared at a loading rate of 100 mg/L.
Details on test conditions:
TEST SYSTEM
- Test vessel: 60 mL, all-glass, airtight closed and completely filled with no headspace
- Type: closed
- Aeration: no aeration
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Adjusted ISO medium

OTHER TEST CONDITIONS
- Photoperiod: 16 hours photoperiod daily
Reference substance (positive control):
yes
Remarks:
Potassium dichromate
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
9.2 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat. (dissolved fraction)
Basis for effect:
mobility
Results with reference substance (positive control):
Potassium dichromate 48h-EC50 0.59 mg/L, within the ranges of the expected responses at the different concentrations, i.e. the 48h-EC50 was between 0.3 and 1.0 mg/L.

Table 1 - Number of Introduced Daphnids and Incidence of Immobility in the Range-Finding Test

Time (h)

Replicate

Tri-n-butyl phosphine (% SS prep. at 100 mg/L)

Control

0.10

1.0

10

 

0

A

5

5

5

5

 

B

5

5

5

5

 

Total introduced

10

10

10

10

 

 

24

A

0 (1)

0

0

0

 

B

0

0

0

0 (1)

 

Total immobilised

0

0

0

0

 

Effect %

0

0

0

0

 

 

 

 

 

 

48

A

0 (1)

0

0

2

 

B

0 (4)

0

0

2#

 

Total immobilised

0

0

0

4

 

Effect %

0

0

0

40

 

( ) between brackets: number of daphnia observed trapped at the surface of the test solutions. These organisms were reimmersed into the respective solutions before recording of mobility

# Microscopic observation revealed no test item attached to the daphnids.

Table 2 - Number of Introduced Daphnids and Incidence of Immobility in the Final Test

Time (h)

Replicate

Tri-n-butyl phosphine (% SS prep. at 100 mg/L)

 

Control

0.46

1.0

2.2

4.6

10

22

0

A

5

5

5

5

5

5

5

B

5

5

5

5

5

5

5

C

5

5

5

5

5

5

5

D

5

5

5

5

5

5

5

Total introduced

20

20

20

20

20

20

20

 

24

A

0

0

0

0

0

0

2 (1)

B

0

0

0

0

0

0

0 (2)

C

0

0

0

0

0

0

2

D

0

0

0

0

0

0

1 (1)

Total immobilised

0

0

0

0

0

0

5

Effect %

0

0

0

0

0

0

25

 

 

 

 

 

 

 

48

A

0

0

0

0

0

4#

5

B

0

0

0

0

 1*

3

5 (3)

C

0 (3)

0

0

0

0

2

5

D

0

0

0

0

0

2

5

Total immobilised

0

0

0

0

1

11

20

Effect %

0

0

0

0

5

55

100

( ) between brackets: number of daphnia observed trapped at the surface of the test solutions. These organisms were reimmersed into the respective solutions before recording of mobility

# Microscopic observation revealed no test item attached to the daphnids

* A total of 6 daphnids were observed (seeAppendix 3).

Validity criteria fulfilled:
yes
Conclusions:
In conclusion, the 48h-EC50 for Daphnia magna exposed to Tri-n-butyl phosphine equalled a concentration representing 9.2% of a saturated solution prepared at a loading rate of
100 mg/L (95% confidence interval between 7.5% and 11% SS).
Executive summary:

The acute toxicity of the test material to freshwater invertebrates was determined in a study conducted in accordance with the standardised guideline OECD 202 under GLP conditions. Daphnia magna were exposed to the test material for 48 hours under static conditions at nominal concentrations 0.46%, 1.0%, 2.2%, 4.6%, 10% and 22% of a SS prepared at a loading rate of 100 mg/L (no solvent). A SS prepared with loading rate was used due to the poor solubility of the test substance.

Under the conditions of the test, the 48h EC50 of the test material to Daphnia magna was determined to be 9.2% of a SS prepared at a loading rate of 100 mg/L.

Description of key information

 Under the conditions of the test, the 48h EC50 of the test material to Daphnia magna was determined to be 9.2% of a SS prepared at a loading rate of 100 mg/L. 

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
9.2 mg/L

Additional information

The acute toxicity of the test material to freshwater invertebrates was determined in a study conducted in accordance with the standardised guideline OECD 202 under GLP conditions. Daphnia magna were exposed to the test material for 48 hours under static conditions at nominal concentrations 0.46%, 1.0%, 2.2%, 4.6%, 10% and 22% of a SS prepared at a loading rate of 100 mg/L (no solvent). A SS prepared with loading rate was used due to the poor solubility of the test substance.

Under the conditions of the test, the 48h EC50 of the test material to Daphnia magna was determined to be 9.2% of a SS prepared at a loading rate of 100 mg/L.