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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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reason / purpose:
reference to same study
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
50 mL of test samples from each replicates were drawn and mixed together for each group at each time point. Samples were take from the freshly prepared solutions at the start of the exposure, from the 24-h spent solutions and the freshly prepared solutions on day 1, and from the 24-h spent solutions on day 2.
Vehicle:
no
Details on test solutions:
Preparation of Test concentrations for CERAPHYL® 41:
On day 0, quantity of 200 mg CERAPHYL® 41 were weighed in two replicate individually, and made up to 2000 with reconstituted water in two different glass bottle (stock A1 and A2) to achieve the final concentration of 100% WAF prepared at 100 mg CERAPHYL® 41/L and kept for continuous stirring using magnetic stirrer for approximate 24 h at room temperature. Test vessel of A1 and A2 were rinsed with test solution of 100 mg CERAPHYL® 41/L. After stirring, test solutions were kept for re-equilibrium for approximate 24 h. After phase separation, test solutions were collected from lower portion by “L” shaped glass tube without disturbing the phase. Volume of 1300 mL was collected from each bottle and mixed together (stock A). To achieve the final concentrations of 9.5, 17.1, 30.9, 55.6% WAF prepared at 100 mg CERAPHYL® 41/L volume of 95, 171, 309 and 556 mL from stock A were made upto 1000 mL with test media, respectively. Four replicates were used for each test concentration with 101 mL of volume in each test vessel. Prior to adding the volume of test solution used for exposure to the test vessels, test vessels were pre-conditioned with respective test concentrations to saturate the surface of the respective vessel to prevent loss of test concentration due to absorption at the walls of the test vessels. Same procedure was followed on day 1 for preparation of test concentration.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISMS:
- Master culture: procured from the Department of Zoology, University of Pune, India and regularly subcultured at the Ecotoxicology Laboratory of Jai Research Foundation.
- Sensitivity validtion: validation study with potassium dichromate as a positive control.
- Feeding: unicellular algae Pseudokirchneriella subcapitata during culturing and 48 h prior to experimentation.
- Age: The experiment was initiated with neonatal daphnids (less than 24 h old).

CULTURE CONDITIONS:
- mean temperature: 20.6 ± 0.1 °C,
- mean dissolved oxygen level: 8.97 ± 0.06 mg/L
- lIGHT/DARK CYCLUS: 16 h light and 8 h dark photoperiod.
- pH: 7.66 ± 0.06
- total hardness: 202.8 mg/L as CaCO3.
- Light Intensity: 1310 Lux.
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
197.6 to 208.0 mg/L as CaCO3
Test temperature:
20.2 - 21.4 °C
pH:
8.04 - 8.26
Dissolved oxygen:
8.51 - 9.00 mg/L
Nominal and measured concentrations:
WAF prepared at 100 mg CERAPHYL® 41/L (%) : 9.5 17.1 30.9 55.6 100
Time Weighed Average measured for the 48-h period : 0.063 0.072 0.108 0.135 0.167 mg/L
Average initial concentrations measured at t= 0h and 24h : 0.076 0.133 0.208 0.350 0.776 mg/L
Details on test conditions:
- Observations: All test daphnids were observed for immobility and abnormal behavior or appearance, if any, at 0, 24 and 48 h of exposure. Mobility of the daphnids was assessed by gently swirling the test container for 15 seconds and observing their swimming behaviour. Those daphnids unable to swim during the agitation of the test container and organisms remaining settled on the water surface or settled at the bottom of the test vessel were recorded as immobile.
- Test conditions: Temperature, dissolved oxygen and pH of the test media were measured using HQ40d (multimeter). Total hardness of the test media was measured using titrimetric method (IS 3025, 1983) prior to treatment.
- Photoperiod: 16 h light and 8 h darkness cycle.
- Other: The whole experiment was conducted in a specially designed low temperature water bath preset to a water temperature of 20.0 °C. Uniform temperature in the water chamber of the water bath was obtained by maintaining a slow flow of water by a motor.
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
0.064 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat. (dissolved fraction)
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
0.095 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat. (dissolved fraction)
Basis for effect:
mobility
Details on results:
The EC50 Value corresponded with 11.5% of a WAF prepared at 100 mg/L, which means that the EC50 was below the solubility limit of Ceraphyl 41.
Results with reference substance (positive control):
The 48h-EC50 of potassium dichromate was 0.61 mg/L with a 95%-confidence interval of 0.44 - 0.84 mg/L.

 Estimated CERAPHYL® 41concentration based on the analytical results using the area percentage for dodecanol used as a standard:

WAF prepared at 100 mg CERAPHYL® 41/L (%)

0 d 0 h

0 d 24 h

Area % Normali-

zed

Measured concentration of dodecanol

(mg/L)

CERAPHYL®

41 concent-

ration

 in mg/L

Area % Normali-

zed

Measured concentration

of dodecanol

(mg/L)

CERAPHYL

® 41 concentration in mg/L

9.5

33.7

0.03

0.089

13.18

0.005

0.038

17.1

33.97

0.05

0.147

15.11

0.005

0.033

30.9

32.03

0.07

0.219

10.2

0.005

0.049

55.6

32.82

0.12

0.366

10.21

0.005

0.049

100

25.9

0.23

0.888

9.99

0.005

0.050

 

WAF prepared at 100 mg CERAPHYL® 41/L (%)

1 d 0 h

1 d 24 h

Area % Normali-zed

Measured concentration of dodecanol

(mg/L)

CERAPHYL® 41 concentration in mg/L

Area % Normali-

zed

Measured concentration

of dodecanol

(mg/L)

CERAPHYL® 41 concentration in mg/L

9.5

31.67

0.02

0.063

6.94

0.005

0.072

17.1

25.53

0.03

0.118

10.76

0.005

0.046

30.9

25.57

0.05

0.196

7.67

0.005

0.065

55.6

27.03

0.09

0.333

9.02

0.005

0.055

100

24.26

0.1

0.412

13.34

0.005

0.037

Immobility recorded in the 48 -h test with Daphnia magna exposed to different concentrations of Ceraphyl 41:

WAF prepared at 100 mg CERAPHYL® 41/L (%)

Time weighted average

(mg/L)

N° of Replicates

N° of Daphnids/

group

Immobility N° and % at

0 h

24 h

%

48 h

%

0.0 (Control)

-

4

20

0

0

0

0

0

9.5

0.063

4

20

0

0

0

8

40

17.1

0.072

4

20

0

2

10

14

70

30.9

0.108

4

20

0

8

40

17

85

55.6

0.135

4

20

0

13

65

20

100

100.0

0.167

4

20

0

13

65

20

100

 

Validity criteria fulfilled:
yes
Conclusions:
Under the test conditions of this study, the EC50 of the test substance was below its solubility limit, i.e. 0.1 mg/L (TWA: 0.064 mg/L).

Description of key information

Propanoic acid, 2-hydroxy-, C12-15-alkyl esters was tested as Ceraphyl 41 in a semi-static 48-h test with Daphnia magna as test organism. The 48h-EC50 was 0.064 mg/l with a 95% confidence interval of 0.053 to 0.078 mg/L. These concentrations were based on the mean of the average measured concentrations for the two 24 -h time intervals. The value is supported by a calculated EC50 of 0.12 mg/L based on the QSAR-estimated EC50 values for the individual lactates.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
0.064 mg/L

Additional information