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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
Specific details on test material used for the study:
Test Item Name Lactic Acid Dodecyl Ester
IUPAC Name Dodecyl lactate
CAS Number 6283-92-7
Batch/Lot Number 20150911001
Analysed Purity
(Genearted at JRF) 75.08%
Manufactured by Finetech Industries Limited
Supplied to JRF by Finetech Industry Limited, U.K.
Date of Expiry April 12, 2017
Date of Re-analysis April 12, 2017
Appearance Light yellow liquid
Analytical monitoring:
yes
Details on sampling:
50 mL of test samples from each replicates were drawn and mixed together for each group at 0 and 24 h at each renewal. For the concentration analysis of main stock solution, 100 mL of test sample from stock A1 was drawn at day 0 and day 1. The samples were divided into two equal portions. One portion (100 mL) was sent for test concentration analysis and the second portion (100 mL) was stored at -20 ± 5 ºC temperature till the study completion.
Vehicle:
no
Details on test solutions:
Preparation of Test concentrations:
On day 0, quantity of 200 mg lactic acid dodecyl ester were weighed in two replicate individually, and made up to 2000 with reconstituted water in two different glass bottle (stock A1 and A2, Test vessel of A1 and A2 were rinsed with test solution of 100 mg lactic acid dodecyl ester/L) to achieve the final concentration of 100% WAF prepared at 100 mg lactic acid dodecyl ester/L and kept for continuous stirring using magnetic stirrer for approximate 24 h at room temperature. 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 1000 mL solution was collected from stock A1.
To achieve the final concentrations of 0.13, 0.28, 0.62, 1.36 and 3.0% WAF prepared at 100 mg lactic acid dodecyl ester/L,volume of 1.3, 2.8, 6.2, 13.6 and 30 mL from stock A1 were made upto 1000 mL with test media, respectively. Four replicates were used for each test concentration with 120.5 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 at 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:
187.2 mg/L as CaCO3
Test temperature:
20.7 - 21.5 °C
pH:
7.50 - 7.79
Dissolved oxygen:
8.47 - 8.81 mg/L
Nominal and measured concentrations:
WAF prepared at 100 mg/L (%) : 0.13 0.28 0.62 1.36 3 100
Concentration measured in fresh solutions at t=0h (mg/L) 0.0164 0.0414 0.0695 0.1342 0.3526 15.2
Concentration measured in fresh solutions at t=24H (mg/L) 0.0159 0.0436 0.0591 0.1442 0.3086 9.9
Average initial concentrations measured at t= 0h and 24h (mg/L) 0.01615 0.0425 0.0643 0.1392 0.3306
Time Weighed Average measured for the 48-h period (mg/L) 0.0151 0.0387 0.0551 0.0954 0.1895
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.:
0.1 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat. (dissolved fraction)
Basis for effect:
mobility
Remarks on result:
other: 95%-confidence interval: 0.085 - 0.12
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 0.67 mg/L with a 95%-confidence interval of 0.42 - 1.07 mg/L.

Lactic acid dodecyl ester concentration based on the analytical results:

Concentration:%WAF prepared at 100 mg Lactic Acid Dodecyl Ester/L

Measured Concentration ofLactic Acid Dodecyl Esterat 0 day 0 h

(mg/L)

Measured Concentration ofLactic Acid Dodecyl Esterat

 0 day 24 h

(mg/L)

Average Exposure Concentration ofLactic Acid Dodecyl Esterduring 24 h period

(0 day)

(mg/L)

0.13

0.0164

0.0146

0.0155

0.28

0.0414

0.0362

0.0387

0.62

0.0695

0.0515

0.0598

1.36

0.1342

0.0654

0.0937

3.000

0.3526

0.0704

0.1576

 

Concentration:%WAF prepared at 100 mg Lactic Acid Dodecyl Ester/L

Measured Concentration ofLactic Acid Dodecyl Esterat 1 day 0 h

(mg/L)

Measured Concentration ofLactic Acid Dodecyl Esterat 1 day 24 h

(mg/L)

Average Exposure Concentration ofLactic Acid Dodecyl Esterduring 24 h period (1 day)

(mg/L)

Concentration: Geometric mean measured concentration of lactic acid dodecyl ester at

48 h[[√(C0f x C24s)+ √(C24f x C48s)]/2 ]

(mg/L)

0.13

0.0159

0.0138

0.0148

0.0151

0.28

0.0436

0.0344

0.0387

0.0387

0.62

0.0591

0.0430

0.0504

0.0551

1.36

0.1442

0.0653

0.0970

0.0954

3.00

0.3086

0.1589

0.2214

0.1895

Immobility recorded in the 48 -h test with Daphnia magna exposed to different concentrations of lactic acid dodecyl ester :

Group

Concentration: %WAF prepared at 100 mg Lactic Acid Dodecyl Ester/L

Concentration: Geometric mean measured concentration of lactic acid dodecyl ester(mg/L)

N° of Replicates

N° of Daphnids/

group

Immobility N° and % at

0 h

24 h

%

48 h

%

G1

0.0 (Control)

-

4

20

0

0

0

0

0

G2

0.13

0.0151

4

20

0

0

0

0

0

G3

0.28

0.0387

4

20

0

0

0

0

0

G4

0.62

0.0551

4

20

0

0

0

2

10

G5

1.36

0.0954

4

20

0

1

5

7

35

G6

3.0

0.1895

4

20

0

3

15

19

95

Validity criteria fulfilled:
yes
Conclusions:
Under the test conditions of this study, the EC50 of the test substance for Daphnia magna was below its solubility limit of approximately 6 mg/L, i.e. 48h-EC50 is 0.1 mg/L.

Description of key information

Propanoic acid, 2-hydroxy-, dodecyl ester was tested in a semi-static 48-h test with Daphnia magna as test organism. The 48h-EC50 was 0.10 mg/l with a 95% confidence interval of 0.085 to 0.12 mg/L. These concentrations were based on the mean of the average measured concentrations for the two 24 -h time intervals.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
0.1 mg/L

Additional information

Based on ECOSAR v1.1 Class-specific Estimations, acute 48h-LC50 for daphnids ranges from 0.669 to 1.368 mg/L. The experimental 48h-EC50 for Daphnia magna of 0.10 mg/L is significantly lower and may be due to the presence of dodecanol with an extrapolated 48h-EC50 of 0.08 mg/L.