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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:
1986-08-05 - 1986-08-06
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: well performed study with some limitations in the experimental design (e.g. exposure period was 24h only)documentation (e.g oxygen concentrations in the vessels were not reported)
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
yes
Remarks:
Test duration 24h
Qualifier:
equivalent or similar to
Guideline:
ISO 6341 (Water quality - Determination of the Inhibition of the Mobility of Daphnia magna Straus (Cladocera, Crustacea))
Deviations:
yes
Remarks:
Test duration 24h
Principles of method if other than guideline:
The reevaluation/validation of older data from Hoechst (Report date 2008-09-04) is based on the raw data from 6.1.3/Hoechst_1986-08-27/W86-254. The test was performed according to DIN 38412, Part 11, a method related to OECD guideline 202 (I) but with a test duration of only 24 instead of 48 hours.
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
-Stock solution: saturated solution prepared by stirring a batch in water at room temperature and filtrating it through a folded paper filter;
- Concentration of stock solution: 630 mg DOC/L, correspoinding to 1053.3 mg/l 2-Chlorobenzaldehyde;
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Strain: Daphnia magna Straus
- Source: own laboratory breed
- Age at study initiation (mean and range, SD): >3h < 24h
- Method of breeding: Adult animals were cultivated in glass vessels (volume: 4 litres). The medium was changed once a week. Twice daily the animals were fed with algae (Scenedesmus supspicatus).

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
24 h
Test temperature:
21°C
pH:
Measured in additional test vessels of each test concentration
Dissolved oxygen:
Measured in additional test vessels of each test concentration
Nominal and measured concentrations:
Nominal concentrations: Dilution of the stock solution with 630 mg DOC/L, correspoinding to 1053.3 mg/l 2-Chlorobenzaldehyde
1:20 corresponding to 53 mg/L test substance;
1:25 corresponding to 42 mg/L test substance;
1:35 corresponding to 30 mg/L test substance;
1:44 corresponding to 24 mg/L test substance;
1:50 corresponding to 21 mg/L test substance;
Details on test conditions:
TEST SYSTEM
- Test vessel: 100 ml glass vessels;
- Test volume: 50 ml;
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Synthetic water according to DIN 38 412 Part 11
- Culture medium identical to test medium;

OTHER TEST CONDITIONS
- Photoperiod: 24h dark

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Immobilization after 24h

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 1.25
Reference substance (positive control):
yes
Remarks:
Potassium dichromate
Duration:
24 h
Dose descriptor:
EC0
Effect conc.:
21 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
24 h
Dose descriptor:
EC10
Effect conc.:
24 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Key result
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
30 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
24 h
Dose descriptor:
EC100
Effect conc.:
53 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Results with reference substance (positive control):
After 24 hours the EC50 of potassium dichromate was between 0.9 mg/l to 1.9 mg/l which is in line with the range of 0.6 mg/l and 2.1 mg/l as required by OECD 2002 (2004).
Reported statistics and error estimates:
The EC0/EC10, EC50 and EC90/EC100 values were estimated graphically in a plot on the probability net.

Table 1: Immobilization rates of Daphnia magna exposed to 2-Chlorobenzaldehyde over a period of 24 hours

Dilution of
the stock
solution

Replicate

Number
of
daphnids
exposed

Number of
immobilized
daphnids

24 h

Percentage of
immobilized
daphnids

24 h

Mean
[%]

24 h

Control

1

10

0

0

0

2

10

0

0

3

10

0

0

4

10

0

0

01:20

1

10

10

100

100

2

10

10

100

01:25

1

10

9

90

95

2

10

10

100

01:30

1

10

8

80

75

2

10

7

70

01:40

1

10

5

50

40

2

10

3

30

01:50

1

10

0

0

0

2

10

0

0

Table 2: Number and percentage of immobilization of Daphnia magna after 24 hours exposed to the reference substance Potassium dichromate

Nominal
test
concen-
tration
[mg/l]

Replicate

Number
of
daphnids
exposed

Number of
immobilized
daphnids

Percentage of
immobilized
daphnids

Mean
[%]

0.9

1

10

3

30

30

 

2

10

3

30

1.9

1

10

8

80

75

 

2

10

7

70

−After 24 hours the EC50 of potassium dichromate was between 0.9 mg/l to 1.9 mg/l which is in line with the range of 0.6 mg/l and 2.1 mg/l as required by OECD 2002 (2004).

−The percentage of immobilized daphnids in the control was below 10%.

−Incubation time was only 24 hours, not 48 hours as required by OECD 2002 (2004).

The EC0/EC10, EC50 and EC90/EC100 values were estimated graphically in a plot on the probability net.

Results-Table 3: ECx values for the immobilization rate of Daphnia magna exposed to 2-Chlorobenzaldehyde over a period of 24 hours

Effect

24 h, Dilution of the
stock solution

24 h, mg DOC/l

24 h, mg/l

EC0

01:50

12.6

21

EC10

01:44

14.3

24

EC50

01:35

18.0

30

EC90

01:25

25.2

42

EC100

01:20

31.5

53

Validity criteria fulfilled:
yes
Conclusions:
With the indicated test data the EC50 of 2-Chlorobenzaldehyde to Daphnia magna under the conditions of the test was estimated to be 30 mg/l. No immobilization was observed at the lowest test concentration of 21 mg/l.
Executive summary:

A toxicity test for 2 -Chlorobenzaldehyde with Daphnia magna Straus was performed close to OECD-guideline 202, albeit with 24h instead of 48h duration. The application of a reference substance (potassium dichromate) resulted in 24h EC50 between 0.9 and 1.9 mg/L, which is in line with the range of 0.6 mg/L and 2.1 mg/L as required by OECD guideline 202 (2004). Not more than 10 % of the daphnids of the control had been immobilized (mean of 4 controls 0% immobilization after 24h) and the dissolved oxygen had been measured albeit data are not recorded. With the indicated test data the EC50 of 2-Chlorobenzaldehyde (tested batch) to Daphnia magna under the conditions of the test was estimated to be 30 mg/l. No immobilization was observed at the lowest test concentration of 21 mg/l.

Description of key information

Test organism: Daphnia magna;
Test guideline: close to OECD 202;
Test duration: 24h;
EC50 Daphnia 30 mg/L
Endpoint: immobilization;

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
30 mg/L

Additional information

The reliable (with restrictions, RL 2) experimental key study was performed close to guideline OECD 202. The test duration however is only 24h (according to OECD 202 part I (1984)) insead of 48 h. The validity criteria are fulfilled and a reference substance (potassium dichromate) confirms the reliability of the study. The values for acute toxicity of 2 -Chlorobenzaldehyde on Daphnia magna are

EC0 = 21 mg/L

EC10 = 24 mg/L

EC50 = 30 mg/L.

No other experimental studies are available. QSAR results are not assignable due to the missing information on validation criteria. The result from the Danish EPA QSAR Database is 39 mg/L and based on the MULTICASE ACUTE AQUATIC TOXICITY model for which substance and organism are confirmed to be inside the model domain. This is very close to the experimental result.