Sodium 3-(2H-benzotriazol-2-yl)-5-sec-butyl-4-hydroxybenzenesulfonate

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

Study period:

1997-09-30 to 1997-10-03

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

edition 1993

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Version / remarks:

Commission Directive 92/69/EEC (edition 1992)

Deviations:

no

Principles of method if other than guideline:

NA

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
NA

Analytical monitoring:

yes

Details on sampling:

All test medium samples for the analytical determinations were taken from the test vessels (after mixing the medium) and kept at -18°C to - 25°C until analysis.

Vehicle:

no

Details on test solutions:

- Stock solution: 200.1 mg test substance was mixed with about 200 mL test medium in a breaker, mixed and filled up to 1000 mL with test medium.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Pseudokirchnerella subcapitata
- Strain: 61.81
- Source (laboratory, culture collection): Sammlung von Algenkulturen, Pflanzenphysiologisches Institut der Universität Göttingen, D-37073 Göttingen
- Method of cultivation: under standardised conditions according to the test guidelines.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

NA

Hardness:

NA

Test temperature:

22.5 - 23.5 °C

pH:

pH (Start) = 7.2 - 7.7
pH (End) = 7.2 - 9.5

Dissolved oxygen:

NA

Salinity:

NA

Nominal and measured concentrations:

Nominal concentrations: 0.9, 1.9, 4.3, 9.4, 21, 45 and 100 mg test substance/L
Measured concentrations: 2.1, 4.5, 9.6, 20.9, 45.5, 101.6 mg test substance/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer flasks, each with 50 mL algal suspension
- Nominal cells density: 10000 cells per mL test solution (+/-10%)
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6
- Light intensity and quality:101 µE/m2sec in the spectral range of 400 to 700 nm

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

34 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 30.7 - 37.9

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

4.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

12 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 8.5 - 14.8

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

3.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 1.6 - 4.8

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

1.9 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

4.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

8.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 7.3 - 10.3

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

9.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

Due to the results of a pre-test the nominal concentrations of test item for the main test were selceted as 0.9, 1.9, 4.3, 9.4, 21, 45 and 100 mg test substance/L. Additionally, a blank control without test substance was tested.
During the test the actual test concentrations in the analysed test media were in the range of 98.57 - 126.32 % of the nominal values.
Consequently, the EC-values were calculated from the nominal concentrations.

Results with reference substance (positive control):

The EbC50 for potassium dichromate after 72 hours of exposure was determined amoung 16 laboratories in an international ring-test with Scenedesmus subspicatus and Pseudokirchnerella subcapitata and found to be at 0.53 mg/L (0.20 to 0.75 mg/L) (reference control at July 11, 1997: EbC50 = 0.60 mg/L).

Reported statistics and error estimates:

The inhibition of algal growth was calculated as EC10 and EC50 (inclusive the 95 % confidence limits) for the biomass b (area under the growth curves) and for specific growth rates µ. The NOEC was determined by testing the mean biomass and mean growth rates of the test concentrations on significant differents to the respective control values (Dunnett-Test).

NA

Validity criteria fulfilled:

yes

Conclusions:

The EC50 (72 h, Pseudokirchnerella subcapitata ) based on growth rate was determined to be 34 mg/L (95% confidence limit 30.7 - 37.9). The NOEC (growth rate, 72 h; Pseudokirchnerella subcapitata) was 4.3 mg/L.
The EC50 (72 h; Pseudokirchnerella subcapitata) based on biomass was determined to be 12 mg/L (95% confidence limit 8.5 - 14.8). The NOEC (biomass, 72 h; Pseudokirchnerella subcapitata) was 1.9 mg/L.

Executive summary:

The toxicity of sodium 3(2H-benzotriazol-2-yl)-5-sec-butyl-4-hydroxybenzenesulfonate towards green algae Pseudokirchnerella subcapitata was assessed for a 72 hours exposue according to EU method C.3 and OECD guideline 201. Due to the results of a pre-test the nominal concentrations of test item for the main test were selceted as 0.9, 1.9, 4.3, 9.4, 21, 45 and 100 mg test substance/L. Additionally, a blank control without test substance was tested. During the test the actual test concentrations in the analysed test media were in the range of 98.57 - 126.32 % of the nominal values. Consequently, the EC-values were calculated from the nominal concentrations. The EC values based on the nominal concentrations were calculated as follows:

Endpoint	Critical effect concentrations (mg/L; 0-72 h)	95% confidence limit
EC50 (biomass)	12	8.5 – 14.8
EC10 (biomass)	3.2	1.6 – 4.8
LOEC (biomass)	4.3
NOEC (biomass)	1.9
EC50 (growth rate)	34	30.7 – 37.9
EC10 (growth rate)	8.8	7.3 – 10.3
LOEC (growth rate)	9.4
NOEC (growth rate)	4.3

The positive control (potassium dichromate) revealed a EbC50 of 0.6 mg/L, which was well within the expected range of 0.2 - 0.75 mg/L and demostrated the validity and sensitively of the test.

Description of key information

EC50(72h) = 34 mg/L for growth rate inhibition of Pseudokirchneriella subcapitata (OECD 201)

NOEC(72h) = 4.3 mg/L for growth rate inhibition of Pseudokirchneriella subcapitata (OECD 201)

Key value for chemical safety assessment

EC50 for freshwater algae:

34 mg/L

EC10 or NOEC for freshwater algae:

4.3 mg/L

Additional information

The toxicity of sodium 3(2H-benzotriazol-2-yl)-5-sec-butyl-4-hydroxybenzenesulfonate towards green algae Pseudokirchnerella subcapitata was assessed for a 72 hours exposure according to EU method C.3 and OECD guideline 201. Due to the results of a pre-test the nominal concentrations of test item for the main test were selceted as 0.9, 1.9, 4.3, 9.4, 21, 45 and 100 mg test substance/L. Additionally, a blank control without test substance was tested. During the test the actual test concentrations in the analysed test media were in the range of 98.57 - 126.32 % of the nominal values. Consequently, the EC-values were calculated from the nominal concentrations. The EC50 (72 h) based on growth rate was determined to be 34 mg/L (95% confidence limit 30.7 - 37.9). The NOEC (growth rate, 72 h) was 4.3 mg/L.