N,N-dicyclohexylbenzothiazole-2-sulphenamide

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 211 (Daphnia magna Reproduction Test)

Version / remarks:

(1998)

GLP compliance:

yes

Analytical monitoring:

yes

Vehicle:

yes

Details on test solutions:

- Dilution Water Source: Elendt M4 medium recommended by OECD TG 211 was used as dilution water.
- Dimethylformamide was used as solvent. 100uL/L of dimethylformamide was contained in the each test soltion.
- Stock Solutions Preparations and Stability: Test chemical was refrigerated. Each test solution was prepared as proper quantity of test chemical was dissolved in 1,000 mL of Elendt M4 contained dimethylformamide. Infrared absorption spectrum of the refrigerated test chemical was detected at the
start and the end of the test, and both spectrums are not contradictory to each other. Solvent was prepared as 40mg/10mL of dimethylformamide diluted to 10 times by dimethylformamide.

Test organisms (species):

Daphnia magna

Details on test organisms:

- Age: < 24 hours old
- Supplier/Source: Test organisms were obtained from National Institute for Environmental Studies (Japan) and had been reproduced in the testing laboratory for 7 years.
- Any pretreatment: Parental daphnids were acclimated for 21 days on test conditions before testing, any groups showing high mortality were not used for testing. The mortality of the daphnids was less than 5% for 2 weeks before testing.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Test temperature:

19.9 - 20.4ºC

pH:

7.4 ¿ 8.5

Dissolved oxygen:

7.4 - 8.8 mg/L

Nominal and measured concentrations:

- Nominal Concentrations: control, solvent control, 0.002, 0.0042, 0.009, 0.019 and 0.04 mg/L
- Time-weighted mean of measured concentration during 21 days: <0.00002, <0.00002, 0.00134, 0.00265, 0.00589, 0.0141, 0.0331 mg/l

Details on test conditions:

- Exposure Vessel Type: 80 mL test solution in a 100mL glass beaker
- Number of Replicates: 10
- Individuals per Replicates: 10
- Renewal Rate of Test Water: everyday
- Light Condition: 16:8 hours, light-darkness
- Feeding: 0.15 mg carbon/day/individual (Chlorella vulgaris: Green Algae)
- Aeration: During test period, test solution did not aerated.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

> 0.033 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

reproduction

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

0.033 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

reproduction

Details on results:

At the highest concentration tested (0.0331 mg/l) no test organism was immobilized.

Results with reference substance (positive control):

EC50(48 hr, immobility) for a reference substance (potassium dichromate) was 0.89 mg/L.

The analysis of the test solutions showed that the ratio of the measured values to the nominal value, ±20%, was exceeded, so the time-weighted average of the measured values was used to calculate the results. The half-life in purified water was 30 hours (0.04 mg/L), and the main reason for the decrease was considered to be hydrolysis.

Result after 21 days exposure

	(mg/L)	95% confidence level (mg/L)
Half lethal concentration (LC50) of parent Daphnia magna	>0.0331	Calculation not possible
50% Reproductive Inhibitory Concentration (EC50	>0.0331	-
No observed effective concentration (NOECi)	>0.0331	-
Minimum concentration of 100% inhibition	>0.0331	-

Validity criteria fulfilled:

yes

Remarks:

Successful positive control

Conclusions:

No effects up to the limit of the water solubilty.

Executive summary:

The chronic toxicity of DCBS to aquatic invertebrates (Dapnia magna) was tested according to OECD TG 211 "Daphnia magna Reproduction test". After 21 days of exposure, an EC50 of >0.331 mg/L and a NOEC of 0.0331 mg/L were obtained (MITI, 2001).

Description of key information

The chronic toxicity of DCBS to aquatic invertebrates (Dapnia magna) was tested

according to OECD TG 211 "Daphnia magna Reproduction test". After 21 days of exposure, an EC50 of >0.0331 mg/L and a NOEC of 0.0331 mg/L were obtained (MITI, 2001).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

NOEC

Effect concentration:

0.033 mg/L