sodium;2-hexadecylsulfanyl-1H-benzimidazole-5-sulfonate

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

Adopted April 13, 2004.

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

sodium;2-hexadecylsulfanyl-1H-benzimidazole-5-sulfonate

EC Number:

616-081-6

Cas Number:

743423-33-8

Molecular formula:

C23 H37 N2 Na O3 S2

IUPAC Name:

sodium;2-hexadecylsulfanyl-1H-benzimidazole-5-sulfonate

Test material form:

solid: particulate/powder

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

Samples for possible analysis were taken from all test concentrations and the control according to the schedule below. The method of analysis is described in the appended Analytical Report.

Frequency at t=0 h and t=48 h
Volume 2.0 mL from the approximate centre of the test vessels
Storage Samples were stored in a freezer (≤-15°C) until analysis at the analytical laboratory of the Test Facility.

At the end of the exposure period, the replicates were pooled at each concentration before sampling.
Additionally, reserve samples of 2.0 mL were taken at the same frequency for possible analysis.

Test solutions

Vehicle:

no

Details on test solutions:

Preparation of test solutions started with loading rates individually prepared at 1.0, 10 and 100 mg/L. A two-day period of magnetic stirring was applied to ensure maximum dissolution of the test item in test medium. Thereafter, the aqueous Water Accommodated Fractions (WAFs) were collected by filtration through a 0.45 µm membrane filter (RC55, Whatman) and used as test concentrations. All test solutions were clear and colorless at the end of the preparation procedure.

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water flea
- Source: In-house laboratory culture with a known history
- Age of parental stock (mean and range, SD): at least third generation
- Feeding during test: no
- Food type: a suspension of fresh water algae
- Frequency: Daily

ACCLIMATION
- Type and amount of food: a suspension of fresh water algae
- Feeding frequency: Daily
- Health during acclimation (any mortality observed): Daphnids originated from a healthy stock, 2nd to 5th brood, showing no signs of stress such as mortality >20%, presence of males, ephippia or discoloured animals and there was no delay in the production of the first brood.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Test conditions

Test temperature:

18-22°C

pH:

7.9

Dissolved oxygen:

8.7-9.4 mg/L

Nominal and measured concentrations:

WAF prepared at 0, 1, 10 and 100 mg/L.
Measured concentrations for control and maximum concentration:
* at t = 0 hours: not detected and 0.0456 mg/L
* at t = 48 hours: 0.000068 and 0.0386 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: 60 mL, all-glass
- Aeration: No aeration of the test solutions.
- No. of organisms per vessel: 5 daphnids per vessel containing 50 mL of test solution
- No. of vessels per concentration (replicates): 4 for highest concentration (20 daphnids), 2 for intermediate concentrations (10 daphnids)
- No. of vessels per control (replicates): 4 (20 daphnids)
- No. of vessels per vehicle control (replicates): not applicable
- Biomass loading rate: 5 daphnids per vessel containing 50 mL of test solution

TEST MEDIUM / WATER PARAMETERS: M7, as prescribed by Dr. Elendt-Schneider

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 hours photoperiod daily
- Light intensity: /

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : immobility

VEHICLE CONTROL PERFORMED: no

RANGE-FINDING STUDY
- Combined limit/range-finding test
- Test concentrations: 0, 0.1, 1, 10, 100 mg/L
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Results and discussion

Effect concentrations

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 0.046 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

No immobility or other effects were observed in the control and any test concentration throughout the test.
Effect concentrations exceeding solubility of substance in test medium: yes

Results with reference substance (positive control):

The actual responses in this reference test with K2Cr2O7 are within the ranges of the expected responses at the different concentrations, i.e. the 48h-EC50 was between 0.3 and 1.0 mg/L. Hence, the sensitivity of this batch of D. magna was in agreement with the historical data collected at Charles River Den Bosch.
The 24h-EC50 was 0.87 mg/L with a 95% confidence interval between 0.80 and 0.95 mg/L.
The 48h-EC50 was 0.54 mg/L with a 95% confidence interval between 0.49 and 0.61 mg/L.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

In conclusion, the 48h-EC50 for Daphnia magna exposed to V182675 was beyond the range tested, i.e. exceeded a measured concentration of 0.046 mg/L corresponding to the maximum solubility of the test item in test medium at a loading rate of 100 mg/L.

Executive summary:

The objectiveof the study was to evaluate V182675 for its ability to generate acute toxic effects on the mobility of Daphnia magna during an exposure period of 48 hours and, if possible, to determine the EC₅₀at 24 and 48 hours of exposure.

The study procedures described in this report were based on the OECD guideline No. 202, 2004.In addition, procedures were based on the test methods described in the OECD series on testing and assessment number 23, 2000.

The batch of V182675 tested was an off-white powder with lumps and a purity of 92.7% and not completely soluble in test medium at the loading rates initially prepared.

Water Accommodated Fractions (WAFs) were individually prepared at loading rates of 1.0 to 100 mg/L and used as test concentrations.

A combined limit/range-finding test was performed. Twenty daphnids per group (5 per replicate, quadruplicate) were exposed to an untreated control and to a WAF prepared at a loading rate of 100 mg/L, in a limit test. In addition ten daphnids per group (5 per replicate, duplicate) were exposed to WAFs individually prepared at 1.0 and 10 mg/L in the combined range-finding test. The total exposure period was 48 hours and samples for analytical confirmation of exposure concentrations were taken at the start and at the end of the test.

No immobility or other effects were observed in the control and any test concentration throughout the study.

Samples taken from the WAF prepared at a loading rate of 100 mg/L were analysed. Analysis of the samples taken at the start of the test showed a measured concentration of 0.046 mg/L, which did not decrease by more than 20% of the initial concentration during the test, i.e. was at 85% (0.039 mg/L) of the initial concentration at the end of the test. Based on these results, effect parameters were based on measured concentrations.

The study met the acceptability criteria prescribed by the study plan and was considered valid.

In conclusion, the 48h-EC₅₀for Daphnia magna exposed to V182675 was beyond the range tested, i.e. exceeded a measured concentration of 0.046 mg/L corresponding to the maximum solubility of the test item in test medium at a loading rate of 100 mg/L.