N-tert-butylbenzothiazole-2-sulphenamide

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

also cited in OECD SIDS.

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

not specified

GLP compliance:

yes

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source (i.e. manufacturer or supplier) and lot/batch number of test material: Batch-Number 612040, Source not mentioned in report
- Purity, including information on contaminants, isomers, etc.: 96.8%

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
The test materials were stored in a refrigerator in our laboratory.
The infrared absorption spectra of the available test substance were measured and confirmed to be consistent with the structure of the test substance. At the end of the test, the infrared absorption spectrum was also measured and compared with the spectrum measured before the start of the test. As a result, there was no change in the spectrum, and the test substance was judged to have been stable during storage.

Analytical monitoring:

yes

Details on sampling:

For all concentration groups (one test vessel for each), 0.75 mL of each test solution at the beginning of exposure and before water change was collected in a measurement vial and analyzed by HPLC after adding an equal volume of acetonitrile. The standard solutions prepared with acetonitrile were diluted with an equal volume of water and used as HPLC measurement samples. The concentration of the test substance in each test solution was determined from the ratio of the peak area to that of the standard solution.

Vehicle:

yes

Remarks:

STOCK AND TEST SOLUTION AND THEIR PREPARATION: Vehicle, solvent: HCO-50 and DMF Concentration of vehicle/solvent: 100 mg/L

Details on test solutions:

50 mg of the test substance was weighed out, dissolved in 100 mg of DMF, added to 1900 mg of HCO-30, and mixed. A stock solution with a test substance concentration of 50 mg/L was prepared by diluting this solution with dilution water to a volume of 1000 mL. In a 500-mL volumetric flask, dilution water was added and the above stock solution of the test substance was added according to each concentration. The test solution was prepared by adding the above test substance stock solution according to each concentration, and then adding the stock solution of solvent to keep the concentration of solvent constant (100 mg/L). The test solution was prepared by adding the stock solution of the solvent to achieve a constant solvent concentration (100 mg/L). The solvent control group was prepared without the test substance alone (solvent concentration: 100 mg/L).
In the control group, only diluted water was used.

Test organisms (species):

Daphnia magna

Details on test organisms:

Juvenile Daphnia magna (Daphnia magna) within 24 hours of birth were used in this study.
The larvae of Daphnia magna were obtained from the National Institute for Environmental Studies (NIES) on July 18, 1995 and have been reared in our laboratory in succession. The concentration of the substrate (potassium dichromate, reagent grade) inhibiting half swimming (EiC50) was 0.23 mg/L in 48 hours.

Breeding conditions:

The larvae (born in January 21, 1997) were used as parents of the test Daphnia magna. These larvae (born on January 21, 1997) were used as the parents of the test Daphnia magna, and were reared under the following conditions. The larvae were removed at least twice a week when they matured and began to produce larvae.

At the beginning of the fourth week, on the day before the start of the exposure, larvae were placed in the grower cell and selected as adult females from those that had 0% mortality and no dormant eggs or males in the previous two weeks. Adult females were selected, and larvae produced the next day (within 24 h) were used for the test (exposure started on the 18th day of February, 1997).

1) Breeding water : Dilution water (see 3.2)
2) Breeding density : As juveniles: 35 or 70 animals /3 L breeding water
As adults: 35 animals / 3 L breeding water
3) Temperature : 20 + 1 °C
4) Illumination : Room light, 16 hours light / 8 hours dark
5) Feeding : Chlorella vulgaris
6) Feeding amount : 0.1～0.2 mgC (organic carbon content) per Daphnia / day

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

65 mg/L (CaCO3 count)

Test temperature:

20.4 +/- 0.3 °C

pH:

7.9 - 8.1

Dissolved oxygen:

7.8 - 8.1 mg/L

Nominal and measured concentrations:

Nominal concentrations: 0.5, 0.75, 1.1, 1.7, 2.5
Measured concentrations 0 hours: 0.549, 0.855, 1.25, 1.91, 2.84
Measured concentrations 24 hours: 0.382, 0.549, 0.719, 0.908, 1.00
Geometric Mean during 24 hours: 0.458, 0.685, 0.948, 1.32, 1.69

all concentrations are given in mg/L

Details on test conditions:

Intensity of irradiation: Photoperiod: 16 hours light/8 hours darkness.
Total amount of test solution was replaced at 24 hours.

Reference substance (positive control):

no

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

1.31 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC100

Effect conc.:

1.69 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

0.948 mg/L

Nominal / measured:

meas. (geom. mean)

Details on results:

The concentrations of test material measured at preparation and after 24 hours were greater than +/- 20 % of the set-up values, therefore, the measured values (geometric average) were used.

Validity criteria fulfilled:

yes

Conclusions:

The toxicity of invertebrates (Daphnia magna) of TBBS was determined at an EC50 of 1.3 mg/L after a period of 48 hours. The toxicity was observed to be greater than the limit of water solubility of TBBS.

Executive summary:

The toxicity of invertebrates (Daphnia magna) of TBBS was determined according at the OECD guideline 202 "Daphnia, Acute Immobilisation Test" and showed an EC50 of 1.3 mg/L after a period of 48 hours. The toxicity was observed to be greater than the limit of water solubility of TBBS.

Description of key information

The toxicity of invertebrates (Daphnia magna) of TBBS was determined at an EC50 of 1.3 mg/L after a period of 48 hours. The toxicity was observed to be greater than the limit of water solubility of TBBS.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

1.3 mg/L

Additional information

Due to fast hydrolysis of TBBS the observed effect is most probably a combined effect from both, TBBS and MBT. Therefore, the value determined for TBBS was chosen as key study. However the effective concentration on Daphnia magna reported in the study for MBT is less sensitive than the one reported for TBBS on algae, and hence the value for MBT was not used in further risk assessment for the PNEC estimation.