N,N-dicyclohexylbenzothiazole-2-sulphenamide

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

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 201 (Alga, Growth Inhibition Test)

Version / remarks:

(1984)

Deviations:

not specified

GLP compliance:

yes

Analytical monitoring:

yes

Vehicle:

yes

Details on test solutions:

- 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. 0.04mg test chemical was dissolved in 1000mL OECD medium included 100uL/L of dimethylformamide and which was used as 0.04 mg/L test solution. 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):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

- Supplier/Source: Obtained from American Type Culture Collection and reproduced in aseptic culture at 6th June 1996.
- Method of Cultivation: Sterile
- Stain Number: ATCC22662
- Pre-culture (duration, medium, etc.): Test alga was pre-incubated for 4 days under the same method of test in OECD medium.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test temperature:

22.8 - 23.3ºC

pH:

7.8 - 7.9 (at the start of the test)
9.3 - 9.7 (at the end of the test)

Nominal and measured concentrations:

- Nominal Concentrations: control solvent control and 0.04 mg/L
- At the start of the test, the deviations from the nominal concentration were less than +/-20%. Although at the end of the test, the measured concentration of 0.04mg/L of the test chemical was 0.00415mg/L or 10% of nominal concentration. The major reason for the decrementation of the test chemical was considered as hydrolysis of the test chemical and aclimination of test chemical to algae.

Details on test conditions:

- Medium: OECD medium
- Exposure Vessel Type: 300mL Erlenmeyer flask
- Number of Replicates: 3
- Initial Cell Number: 10,000 cells/Ml
- Light Condition: 4,000 lux (+/- 20%), continuously
- Shaking: 100 rpm

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 0.012 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.012 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Results with reference substance (positive control):

EbC50 (0-72 hr) for a reference substance (potassium dichromate) was 0.473 mg/L.

Growth Curves: During the test period algae grew almost linearly(log scale) in each concentration.

As a result of the analysis of the test solution, the ratio of the measured value at the beginning of exposure to the
nominal value was higher than the nominal value, so the nominal value was used to calculate the inhibitory
concentration.

Inhibition concentration by comparison of area under the growth curve:

50% growth inhibitory concentration (Ebc50) (0-72) : >0.0400 mg/L (95%- confidence limit: None)

No observed effective concentration NOECb (0-72) : >0.0400 mg/L

Inhibition concentration by comparison of growth rate:

50% Growth inhibition concentration ErC50 (24-48) : >0.0400 mg/L (95%- confidence limit: None)

No observed effective concentration NOECr (24-48) : >0.0400 mg/L

50% Growth inhibition concentration ErC50 (24-72) : >0.0400 mg/L (95%- confidence limit: None)

No observed effective concentration NOECr (24-72) : >0.0400 mg/L
 

Validity criteria fulfilled:

yes

Conclusions:

A limit test with a test concentration of 0.012 mg/L was performed on Selenastrum capricornutum (new name: Pseudokirchnerella subcapitata) in a static test system according to OECD 203 (MITI, 2001) and no toxic effect was observed; and hence a 72-hour EC50 of >0.012 mg/L and a 72 -hour NOEC of 0.012 mg/Lcan be concluded (MITI, 2001).

Executive summary:

A limit test with a test concentration of 0.012 mg/L was performed on Selenastrum capricornutum (new name: Pseudokirchnerella subcapitata) in a static test system according to OECD 203 (MITI, 2001) and no toxic effect was observed; and hence a 72-hour EC50 of >0.012 mg/L and a 72 -hour NOEC of 0.012 mg/Lcan be concluded (MITI, 2001).

Description of key information

A limit test with a test concentration of 0.012 mg/l was performed on

Selenastrum capricornutum (new name: Pseudokirchnerella subcapitata) in a static test system according to OECD 203 (MITI, 2001) and no toxic effect was observed; and hence a 72-hour EC50 of >0.012 mg/l and a 72-hour NOEC of 0.012 can be concluded (MITI, 2001).

Key value for chemical safety assessment

EC50 for freshwater algae:

0.012 mg/L

EC10 or NOEC for freshwater algae:

0.012 mg/L

Additional information

Should read >0.012 mg/L