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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:
Study Initiation Date: 17 August 2016 Experiment End Date: 31 August 2016 Study Completion Date: 10 September 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Version / remarks:
13 April 2004
Deviations:
no
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
Test concentration analysis was done at Auriga Research Ltd, Unit-III, No. 136, 6th Cross, 2nd Stage, Yeshwanthpur industrial suburb, Bangalore-560022.
During range finding study and main study, samples from all the test concentrations was collected at 0 hour on day 0 for the analysis of test concentration and at 48 hour on day 2 for stability analysis. The samples were collected from the central point of the test vessel. The validated analytical method for determination of test concentrations analysis of DOTE was used for analytics.
The test concentration samples were collected in duplicates (2 x 10 mL) for each test concentrations including vehicle control and transferred at ambient condition for test concentration confirmation analysis to Auriga Research Ltd, Unit-III, No. 136, 6th Cross, 2nd Stage, Yeshwanthpur industrial suburb, Bangalore-560022. Results are based on measured concentration, the concentration of test substance has been satisfactorily maintained within 20 percent of nominal concentration.
Vehicle:
yes
Details on test solutions:
Based on the in house dissolution test DOTE was miscible in DMSO (100 µL/L) and reconstituted water. Hence DMSO (100µL/L) and reconstituted water will be selected as the vehicle for preparation of test item formulation.
Test organisms (species):
Daphnia magna
Details on test organisms:
In house maintained Daphnia magna procured, from Environmental and Molecular Toxicology Division, Department of Zoology, Karnataka University, Karnataka, India.
Young daphnids less than 24 h old. (Derived from healthy stock showing no signs of stress, such as high mortality rate, discolored daphnids, presence of male and ephippia, delay in the production of the first brood).
Test type:
static
Water media type:
freshwater
Total exposure duration:
48 h
Remarks on exposure duration:
Duration of the experiment was 48 hour. Experiment was conducted in static condition i.e., the test media was not renewed until completion of the exposure period of 48 hour
Hardness:
216-220 mg CaCO3/L
Test temperature:
20.2-20.3 °C
pH:
6.29-3.8
Dissolved oxygen:
At the end of Test
7.16 mg/ in control
7.10 in test vessels
Nominal and measured concentrations:
Range Finding Study
A range finding (RF) study with 6 concentrations of 0.01, 0.1, 1.0, 10.0, 50.0 and 100.0 mg/L of DOTE was used along with controls (negative and solvent) to find out the range of the lethal concentrations.

Main Study
Based on results of the range finding study, the main study was conducted at the scattered concentrations of 0.05, 0.1, 1.0, 5.0, 20.0 and 40 mg/L specified by the sponsor (rationale of concentration spaced is not as per geometric factor specified in guideline, OECD 203 Daphnia sp., Acute Immobilization Test) along with the control groups (negative and solvent groups).
Reference substance (positive control):
yes
Remarks:
Potassium dichromate
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
24.12 mg/L
Basis for effect:
mobility
Validity criteria fulfilled:
yes
Conclusions:
Based on the results of the experiment and under the experimental conditions employed, it can be concluded that the 48 hour acute median effective concentration (EC50) of DOTE onDaphniais 24.12 mg/L.
The No Observed Effect Concentration (NOEC) and Lowest Observed Effect Concentration (LOEC) over the 48 hour exposure period were 0.05 and 0.1 mg/L of DOTE, respectively.
The United Nations Globally Harmonized System [GHS] sets classification criteria for the 48-hour aqueous EC50in Crustacea [e.g. Daphnia]. The EC50of DOTE inDaphniais 24.12 mg/L and the current GHS criteria indicate an EC50of a substance which is >10 mg/L and <100 mg/L should be assigned Acute Category 3 for hazards to the aquatic environment.
Executive summary:

The test item DOTE provided by Galata Chemicals LLC., was evaluated for 48-hour acute toxicity onDaphniain accordance with OECD Guideline No. 202, “Daphina sp., Acute Immobilisation Test”.

This study of DOTE onDaphniawas performed to determine the 48 hour 50% Effective Concentration (EC50) for immobility and to determine Lowest Observed Effect Concentration (LOEC) and No Observed Effect Concentration (NOEC).

Daphnids were exposed for the test item under static condition.Daphnidswere observed at 24 and48 hoursforsigns of toxicity and immobility during exposure.

For the range finding study duplicate containers of 5 daphnids at each concentration plus control groups (negative and solvent) were used. Daphnids were exposed to test concentrations of 0.01, 0.1, 1.0, 10.0, 50.0 and 100.0 mg/L of DOTE. . Cumulative immobility of 10.0, 10.0, 20.0, 40.0 and 100.0%, respectively, was observed within the DOTE test groups. There were recorded observations of daphnids localized on the bottom of the container at the tested concentration of 1.0 mg/L. Lethargy in addition to daphnids localized on the bottom of container were observed at the tested concentrations of 10.0, 50.0 and 100.0 mg/L of DOTE during the 48 hours of observation period. No clinical signs or immobility were observed in negative or solvent controls during the 48 hour exposure period.

Based on the results of the range finding study, the main study was conducted at concentrations of 0.05, 0.1, 1.0, 5.0, 20.0 and 40.0 mg/L of DOTE in the aqueous test medium. Quadruplicate containers of 5 daphnids at each concentration plus negative and solvent controls were included.

Cumulative immobility of0.0, 10.0, 15.0, 30.0, 55.0 and 100.0% was observed at DOTE test concentrations 0.05, 0.1, 1.0, 5.0, 20.0 and 40.0 mg/L, respectively. No clinical signs or immobility were observed in negative or solvent controls during the 48 hour exposure period.

Daphnids were observed localized on the bottom of container at the tested concentration of 0.1 mg/L Lethargy was observed in addition to daphnids localized on the bottom of container at the tested concentrations of 1.0, 5.0, 20.0 and 40.0 mg/L. No clinical signs or immobility were observed in negative or solvent controls or at the test concentration of 0.05 mg/L DOTE during the 48 hour exposure period. 

The test concentrations at the 0 hour were analytically confirmed to be within in the acceptable range of ± 20% recovery to the nominal concentrations. The test concentrations at 48 hours were ??????? analytically confirmed to be at ??? of the nominal concentrations.

Conclusion

Based on the above results of the experiment and under the experimental conditions employed, it can be concluded that the 48 hour acute median effective concentration (EC50) of DOTE onDaphniais 24.12 mg/L.

The No Observed Effect Concentration (NOEC) and Lowest Observed Effect Concentration (LOEC) over the 48 hour exposure period were 0.05 and 0.1 mg/L of DOTE, respectively.

The United Nations Globally Harmonized System [GHS] sets classification criteria for the 48-hour aqueous EC50in Crustacea [e.g. Daphnia]. The EC50of DOTE inDaphniais 24.12 mg/L and the current GHS criteria indicate an EC50of a substance which is >10 mg/L and <100 mg/L should be assigned Acute Category 3 for hazards to the aquatic environment.

The 48 hour acute median effective concentration (EC50) of Potassium dichromate on Daphnia was 0.90 mg/L[RC1] (BIO-ET 051). This 48 hour EC50of Potassium dichromate lie in the validity criteria acceptance range (0.60 to 2.12 mg/L) towards test system response and test procedure followed. Hence this test with reference standard establishes the acceptability of test system response and test procedure followed

 [RC1]Was this positive control part of this experiment? IF it was, the data should be presented in the tables. If it was not, then put this text in the validity criteria section along with oxygen etc.

Description of key information

Based on the above results of the Key study, it can be concluded that the 48 hour acute median effective concentration (EC50) of DOTE onDaphnia is 24.12 mg/L.

The No Observed Effect Concentration (NOEC) and Lowest Observed Effect Concentration (LOEC) over the 48 hour exposure period were 0.05 and 0.1 mg/L of DOTE, respectively.

The United Nations Globally Harmonized System [GHS] sets classification criteria for the 48-hour aqueous EC50in Crustacea [e.g. Daphnia].

The EC50of DOTE in Daphnia is 24.12 mg/L and the current GHS criteria indicate an EC50of a substance which is >10 mg/L and <100 mg/L should be assigned Acute Category 3 for hazards to the aquatic environment.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
24.12 mg/L

Additional information

There are two additional studies summarised for this endpoint; both were conducted under GLP conditions.

Both studies were conducted with a test item containing ca. 3 -4 % of Ethylhexylthioglycolate (EHTG, CAS: 7659 -86 -1, EC: 231 -626 -4) as impurity

EHTG is better soluable in water as DOTE and shows the following ecotoxicity:

EC50 (48 h) Daphnia = 0.38 mg/L

EC50 Algae = 0.41 mg/L

and is thus classified as Aquatic Acute 1 H400 and Aquatic Chroinic H410

Is likely that the observed effects in both studies are caused or exacerbated by the impurity EHTG