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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:
1999-04-16 to 1999-05-24
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Justification for type of information:
The read across justification is included as attachment to section 13 in the IUCLID dataset.
Reference:
Composition 0
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Version / remarks:
1992
GLP compliance:
yes
Test material information:
Composition 1
Analytical monitoring:
yes
Details on sampling:
- Concentrations: Analysis of all test concentrations plus a control at test start and after 48 hours of exposure.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: 95 mg/L of the test substance was weighed into water, treated for 60 seconds at 8000 rpm with an ultra-turrax and afterwards stirred for 24 h on a magnetic stirrer. Emulsion was filtered using a folded filter of the pore size 7-12 µm to eleminate undissolved particles. M4-Medium according to Elendt and BGA (1992) used for dilution.
- Controls: M4-Medium according to Elendt and BGA (1992)
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna STRAUS
- Source: cloned at the Federal Health Office (BGA) in Berlin; Origin of test animals: laboratory bred
- Age at study initiation (mean and range, SD): 0 - 24 h
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
15.3°dH (dilution water)
Test temperature:
19.2 - 19.4°C (48 h)
pH:
7.4 - 8.1 (48 h)
Dissolved oxygen:
4.0 - 8.7 mg/L (48 h)
Nominal and measured concentrations:
- nominal: 0 (control), 14.0, 28.0, 56.0 mg/L
- mean measured: < 3 (control), 18.0, 31.5 and 54.0 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: so-called "Karlsruher Flaschen" with stoppers
- Type: closed
- Material, size, headspace, fill volume: 250 - 300 ml test medium and had space
- Aeration: not ventilated
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): no data

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: M4-Medium according to Elendt and BGA (1992)
- Culture medium different from test medium: no

OTHER TEST CONDITIONS
- Photoperiod: 16 hours light / 8 hours dark

EFFECT PARAMETERS MEASURED (with observation intervals if applicable):
- number of immobile daphnids after 24 h and 48 h

TEST CONCENTRATIONS
- Test concentrations: 14, 28, 56 mg/L (nominal)
Reference substance (positive control):
no
Duration:
24 h
Dose descriptor:
EC0
Effect conc.:
14 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
56 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: directly derived from raw data
Duration:
24 h
Dose descriptor:
EC100
Effect conc.:
> 56 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EC0
Effect conc.:
18 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
36 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: geometric mean of EC0 and EC100, recalculated based on raw data
Duration:
48 h
Dose descriptor:
EC100
Effect conc.:
54 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
The analytical results for the lowest concentration differ by > 20% from the nominal concentration of 14 mg/L. Therefore all results after 48h are calculated based on mean measured concentrations.

Table 1: Results after 24 h and 48 h

Nominal concentration [mg/L]

Results after 24 hours and 48 hours

Immobile daphnids

Oxygen content [mg/L]

after

48 h

pH

after

48 h 

Temperature [°C]

after 48 h

absolute

%

24 h

48 h

24 h

48 h

0 (control)

0

0

0

 8.7

8.1

19.4

14

0

0

0

0

5.5

7.8

19.3

28

6

16

30

80

4.6

7.5

19.2

56

10

20

50

100

4.0

7.4

19.2

Table 2: Analytical Results

Nominal concentration test substance

[mg/L]

Results by start of test and after 48h

[mg TOC/L]

Mean measured concentration test substance

[mg/L]

0h

48h

Control

< 2

< 2

< 3

14

11

13

18.0

28

20

22

31.5

56

35

37

54.0

Validity criteria fulfilled:
yes
Conclusions:
EC50 (48 h): 36.0 mg/L based on mobility of Daphnia magna (EU method C.2).
The toxicity of Ethyl caproate to Daphnia magna was determined in a GLP study according to EU method C.2. The EC50 of 36 mg/L was recalculated from the geometric mean measured values of the EC0 and the EC100 based on raw data.
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
The read across justification is included as attachment to section 13 in the IUCLID dataset.
Reason / purpose:
read-across source
Related information:
Composition 1
Test material information:
Composition 1
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
36 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
other: Ethyl hexanoate (CAS no. 123-66-0)
Basis for effect:
mobility
Remarks on result:
other: geometric mean of EC0 and EC100, recalculated based on raw data
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
25.5 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
other: Target substance
Basis for effect:
mobility
Remarks on result:
other: recalculated value to correct differences in molecular weight between source (MW = 144.2114 g/mol) and target (MW = 102.132 g/mol).
Conclusions:
The toxicity of Ethyl propionate to aquatic invertebrate (Daphnia magna) was predicted from the source substance Ethyl hexanoate (CAS no. 123-66-0) (see read across justification). The effect value (immobility; EC50) was predicted to be 36 mg/L. The recalculated value to correct differences in molecular weight between source (MW = 144.2114 g/mol) and target (MW = 102.132 g/mol) was 25.5 mg/L.
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
in 1988
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
other: The publication describes only a 24 hour effect value for D. magna as it is a preliminary test. This value is not comparable to an effect value after 48 hours exposure. In addition, no details about the test design is reported.
Reference:
Composition 0
Qualifier:
according to
Guideline:
other: No details about the guideline used are reported
Principles of method if other than guideline:
No data.
GLP compliance:
no
Test material information:
Composition 1
Analytical monitoring:
no
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: water flea
- Strain/clone: IRCHA
- Source: own (maintained since 1978)
Total exposure duration:
24 h
Reference substance (positive control):
yes
Remarks:
Potassium dichromate
Key result
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
286 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
24 h
Dose descriptor:
EC0
Effect conc.:
173 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Results with reference substance (positive control):
- Results with reference substance valid? yes
- Relevant effect levels: The 24 h - EC50 was determined at 0.35 mg/L which indicates a normal toxicity response of the test organisms

Table 1: Acute toxicity results with Ethyl propionate

Acute toxicity test with D. magna

24 h - EC 0

(nominal)

24 h - EC 50

(nominal)

173 mg/L

286 mg/L

Validity criteria fulfilled:
not specified
Conclusions:
The short-term toxicity of Ethyl propionate on Daphnia magna was tested (preliminary study) to determine the test concentration for a main test (long-term toxicity). An EC50 value after 24 hours exposure was determined as 286 mg/L. As no further details about the method or test conduction are reported, the study was set to a reliability of 3. The results of the test, however, support the read across worst case approach for the short-term toxicity to aquatic invertebrates endpoint.

Description of key information

EC50 (48 h) = 25.5 mg/L (Daphnia magna, OECD 202)

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
25.5 mg/L

Additional information

To assess the toxicity of the test substance to aquatic invertebrates one study is available. Since this study is not reliable (the test duration was only 24 h) a read-across approach to Ethyl hexanoate (CAS no. 123 -66 -0) was used to cover this endpoint.

Both substances have a similar chemical structure and corresponding physicochemical properties. In addition they show similarity in their environmental fate such as biodegradability and in their ecotoxicity effects, whereby Ethyl hexanoate is more toxic to aquatic organisms than Ethyl propionate. This is especially reflected in the lower EC50 (24 h) value of 56 mg/L when Ethyl hexanoate is tested on Daphnia magna compared with a higher EC50 (24 h) of 286 mg/L when Ethyl propionate is tested. Ethyl hexanoate can therefore be considered as worst case and is proposed suitable to predict the short-term toxicity to aquatic invertebrates of the target substance Ethyl propionate.

The toxicity of the read-across substance to aquatic invertebrates was determined in a static test performed according to EU method C.2 and GLP. Individuals of Daphnia magna were exposed to nominal test concentrations of 14, 28 and 56 mg/L, equivalent to geometric mean measured concentrations of 18, 31.5 and 54 mg/L. The test concentrations were analysed by TOC determination at test start and after 48h. The analytical results for the lowest concentration differ by > 20% from the nominal concentration of 14 mg/L. Therefore all results after 48h are calculated based on mean measured concentrations.

After 48 h 100% immobility was observed at 54 mg/L whereas 0% immobility was recorded at nominal 18 mg/L. The EC50 values after 24 hours and 48 hours were calculated based on raw data at 56 mg/L (nominal) and 36 mg/L (mean measured), respectively.

The determined EC50 value of 36 mg/L for the source substance was correct for the target substance by taking into account the difference in molecular weight between source (MW = 144.2114 g/mol) and target (MW = 102.132 g/mol) substance. For the target substance a EC50 (48 h) of 25.5 mg/L was calculated.