2,4,7,9-Tetramethyldec-5-yne-4,7-diol, ethoxylated

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Remarks:

study is ongoing, start of the main study (experimental part) November 2022

Adequacy of study:

key study

Study period:

Nov-Dec 2022

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

Analytical pretest:
During a non-GLP validation process the analytical method for the determination of test item CAD-2021-941 in solvent (Acetonitrile/M4 Medium 50/50) was validated with regard to recovery, linearity of detector response, repeatability, specificity, limit of quantification and limit of detection. The stability of test item in solvent was verified.

Nominal test item concentration 9.5, 17, 31, 56 and 100 mg/L (spacing factor 1.8) mg/L

- Sampling method:
Duplicate samples were taken from each test concentration and the control at the start and at the end of the exposure (after 48 hours).
For the 48-hour stability samples, the contents of the respective replicates were combined prior to sampling.
The concentrations of CAD-2021-941 were analyzed in one of the duplicate test medium samples from the control and the two highest nominal test concentrations of 56 and 100 mg/L from both sampling times (0 and 48 hours). The samples from the lower test concentrations were below the 48 hour NOEC determined in this test and, thus, were not relevant for the interpretation of the biological results.

- Sample storage conditions before analysis:
All samples were stored frozen (at -20 ± 5 °C) immediately after sampling.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method:
The test medium of the highest nominal concentration of 100 mg/L was prepared by mixing 102.04 µL of the test item into 1000 mL of test water using intense stirring for 15 minutes at room temperature. This volume is equivalent to a concentration of 100 mg/L, considering the density of the test item of 0.98 g/cm3. No auxiliary solvent or emulsifier was used. The lower test concentrations were prepared by serial dilution steps.
- Concentration of vehicle in test medium (stock solution and final test solution(s) or suspension(s) including control(s)):
Stock solution: 100 mg/L
- Evidence of undissolved material (e.g. precipitate, surface film, etc.):
All solutions were clear with no evidence of undissolved test item.
- Other relevant information:
The test medium was prepared just before the introduction of the daphnids (i.e., start of the test and prior to the test medium renewal).

Reconstituted test water (ISO Test water) according to the OECD Guideline No. 202 will be used in the study. It will consist of analytical grade salts dissolved in purified water to obtain the following nominal concentrations:

Ingredients / Properties Concentration
[mmol/L] [mg/L]
CaCl2 × 2H2O 2.0 294
MgSO4 × 7H2O 0.5 123
NaHCO3 0.75 65
KCl 0.075 5.8
Water Hardness 2.5 250 as CaCO3
Alkalinity 0.8 ---

The analytical results of the range finding test demonstrated the stability of the test item during the test for all treatments with 91 to 109 % of nominal concentrations measured at the start of the test and 105 to 109 % after 48 hours test duration.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water flea
- Strain/clone:
Species Daphnia magna Straus. A clone of this species (originally from the Daphnia Collection of the University of Basel/Switzerland in 2015) is successfully bred in IES Ltd Laboratories under temperature and light conditions identical to those of the tests.
- Age at study initiation (mean and range, SD): 6-24 hours
- Source: IES Ltd Laboratories
- Feeding during test: no
- Food type: algal suspension of the green algae Desmodesmus subspicatus
- Amount:
- Frequency:

Test type:

static

Water media type:

freshwater

Remarks:

Reconstituted test water (ISO Test water) according to OECD Guideline No. 202 was used in the study. It consisted of analytical grade salts dissolved in purified water. Refer to the attached table.

Limit test:

no

Total exposure duration:

48 h

Hardness:

250 mg/L as CaCO3 (2.5 mmol/L)

Test temperature:

21°C

pH:

7.9

Dissolved oxygen:

The test water was aerated prior to the start of the study until oxygen saturation was reached. During the test period, the test water was not aerated.
At the beginning and end of the test period, the dissolved oxygen concentration in the test media and the control was at least 8.3 mg/L

Nominal and measured concentrations:

Nominal: 9.5, 17, 31, 56 and 100 mg/L
Measured:
-Start: 96-98 % of nominal values
-End: 94-101 % of nominal values

Details on test conditions:

TEST SYSTEM
- Test vessel: glass beakers
- Type (delete if not applicable): The test vessels were loosely covered with glass sheets to reduce the loss of water by evaporation and to avoid the entry of dust into the solutions.
- Material, size, headspace, fill volume: 100-mL glass beakers filled with 50 mL of test medium
- Volume of solution: 50 mL
- Aeration: The test water was aerated prior to the start of the study until oxygen saturation was reached. During the test period, the test water was not aerated.
- Type of flow-through (e.g. peristaltic or proportional diluter):
- Renewal rate of test solution (frequency/flow rate): static test
A static test design without test medium renewal was chosen since in a pre-experiment, the test item concentration in the test medium was constant during the test period of 48 hours.
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Alkalinity: 0.8 mmol/L
- Ca/mg ratio: The ratio of Ca:Mg was 4:1
- Intervals of water quality measurement: At the start and end of the test, the pH values, dissolved oxygen concentrations and water temperature were determined in each treatment with surviving daphnids. Additionally, the water temperature was continuous monitored in a separate vessel placed in the test area. The appearance of the test media was visually controlled and documented daily.

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16-hour light to 8-hour dark cycle with a 30-minute transition period
- Light intensity: 18.0 µmol m-2 s-1

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
The immobility of the daphnids was determined by visual inspection after 24 and 48 hours of exposure. Those daphnids not able to swim within 15 seconds after gentle agitation of the test vessel were considered to be immobilized.
Observations were also performed for other non-lethal effects after at least 24 and 48 hours of exposure.

RANGE-FINDING STUDY
- Test concentrations: 1.0, 10 and 100 mg/L
- Results used to determine the conditions for the definitive study: 0% of Daphnids showed immobilization at any concentration. The Daphnids at 100 mg/L were discoloured/ pale at 48 hours

Reference substance (positive control):

yes

Remarks:

For evaluation of the quality of the daphnia clone and the experimental conditions, potassium dichromate is tested as a positive control twice a year.

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

>= 56 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

48 h

Dose descriptor:

EC0

Effect conc.:

ca. 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC100

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Behavioural abnormalities:
- Other biological observations: pale and colourless test animals at the highest concentration
- Mortality of control: 0%
- Other adverse effects control: no
- Immobilisation of control: no
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: no
- Effect concentrations exceeding solubility of substance in test medium: no

Results with reference substance (positive control):

The result of the latest positive control test in October 2022 (24-hour EC50: 1.6 mg/L, IES Study 20220371) showed that the sensitivity of the test organisms was within the range given by the guideline (OECD 202: 24-hour EC50: 0.60 2.1 mg/L).

Reported statistics and error estimates:

Statistical analysis was performed using ToxRat Professional®

The results of the range finding experiment were as follows:

 

Treatment / Test Item Concentration [mg/L]	% Immobilization after 24 Hours	% Immobilization after 48 Hours
Control	0	0
1.0	0	0
10	0	0
100	0	0 (100D)

 

Values in parenthesis:         percent of mobile test animals with adverse effects

                                       D:      daphnids discolored/pale

 

Validity criteria fulfilled:

yes

Conclusions:

The test item CAD-2021-941 had no acute toxic effects on the mobility of Daphnia magna in a 48-hour static test. Nevertheless, all daphnids showed non-lethal effects (pale and colorless test animals) after 48 hours of exposure at the highest test concentration of 100 mg/L.

The 48-hour EC50 and EC100 values were determined to be higher than 100 mg/L and the
48-hour NOEC was determined to be at 56 mg/L. The EC0 was determined to be at 100 mg/L.

Executive summary:

The acute toxicity of CAD-2021-941 to Daphnia magna was determined in a 48‑hour static test according to the OECD Guideline for Testing of Chemicals No. 202 (2004).

The test item CAD-2021-941 had no acute toxic effects on the mobility of Daphnia magna in a 48-hour static test. Nevertheless, all daphnids showed non-lethal effects (pale and colorless test animals) after 48 hours of exposure at the highest test concentration of 100 mg/L.

The 48-hour EC50 and EC100 values were determined to be higher than 100 mg/L and the
48-hour NOEC was determined to be at 56 mg/L. The EC0 was determined to be at 100 mg/L.

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
This read-across is based on the hypothesis that source and target substances have similar toxicological properties because
- they are manufactured from similar precursors under similar conditions
- they share structural similarities with common functional groups: the substances start with an acetylene group as core structure; geminal hydroxyl groups on the alpha carbon atoms; distal to the geminal hydroxyl groups is an isobutyl group (methyl isopropyl); the target substance 2,4,7,9-Tetramethyl-5-decyne-4,7-diol, ethoxylated (1.3) is further functionalised with ethylene oxide and has an ethoxylation degree of 1.3; the source substance 2,4,7,9-Tetramethyl-5-decyne-4,7-diol, ethoxylated (3.8) has an ethoxylation degree of 3.8
- they have similar physicochemical properties and thus, show a similar toxicokinetic behaviour
- they are expected to undergo similar metabolism: oxidation of the terminal methyl groups to result in alcohol, aldehyde and finally the corresponding acid

Therefore, read-across from the existing toxicity, ecotoxicity, environmental fate and physicochemical studies on the source substances is considered as an appropriate adaptation to the standard information requirements of REACH regulation.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
see “Justification for read-across” attached to IUCLID section 13

3. ANALOGUE APPROACH JUSTIFICATION
see “Justification for read-across” attached to IUCLID section 13

4. DATA MATRIX
see “Justification for read-across” attached to IUCLID section 13

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Analytical monitoring:

no

Test organisms (species):

Daphnia magna

Test type:

static

Water media type:

freshwater

Total exposure duration:

48 h

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

88 mg/L

Conclusions:

48 h EC50 = 88 mg/L

Description of key information

The test item CAD-2021-941 had no acute toxic effects on the mobility of Daphnia magna in a 48-hour static test. The 48-hour EC50 value was determined to be higher than 100 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

>= 100 mg/L

Marine water invertebrates

Marine water invertebrates

Dose descriptor:

LC50

Effect concentration:

166 mg/L

Additional information

In an acute toxicity study with the marine crustacean Acartia tonsa, the toxicity of the test substance 2,4,7,9-Tetramethyl-5-decyne-4,7-diol, ethoxylated (3.8), measured as LC50 after 48 hours, was found to be 166 mg/l.