A mixture of: sodium/potassium 7-[[[3-[[4-((2-hydroxy-naphthyl)azo)phenyl]azo]phenyl]sulfonyl]amino]-naphthalene-1,3-disulfonate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Remarks:

Scenedesmus subspxcatus

Type of information:

experimental study

Adequacy of study:

key study

Study period:

06 August 1992 to 02 December 1992

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Official Journal of the European Communities, No. L 133/89-94, May 30 1988: "Algal Inhibition Test"

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Name: FAT 45'155/B
Batch No.: TV 1
Expiration date: May 15, 1997
Chemical name of active ingredients : Disazo Acid Red HT 3728
Solubility in water: about 100 g/l
pH in aqueous solution: pH 7 at a concentration of 1 g/l
Stability: in water: > 2 hours
Aggregate state at room temperature: solid (powder)
Colour: red
Storage: at room temperature, protected from light

Analytical monitoring:

yes

Details on sampling:

Samples were taken out of all flasks under steril conditions after 24, 48 and 72 hours of exposure.

Vehicle:

no

Details on test solutions:

The stock solution was prepared by dissolving the test substances in test water (1.0 g/L). Adequate volumes of this stock solution were added to test water to prepare the test media of the nominal test concentrations of 4.6, 10.0, 21.4, 46.3 and 100.0 mg/L. A control was tested in parallel.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

- Strain No.: 86.81 SAG
- Source: Supplied by the "Sammlung von Algenkulturen, Pflanzenphysiologisches institution der Universität Göttingen"
- Culture condition: under standardized condition according to the test guidelines.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

no data

Test temperature:

22.8 to 23.3 ℃

pH:

test start: 7.7-7.8
test end: 8.0-10.0

Dissolved oxygen:

no data

Salinity:

no data

Nominal and measured concentrations:

Nominal: 4.6, 10.0, 21.4, 46.3 and 100.0 mg/L
Measured: 84.1 % - 120.5 % of the nominal concentration

Details on test conditions:

TEST SYSTEM
- Initial cells density: 10000 cells per mL test medium
- No. of organisms per vessel: 50 mL algae suspension per replicate
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: Yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:
- Conductivity: 0.1 μs/cm
- Intervals of water quality measurement: Start and end of the test

OTHER TEST CONDITIONS
- Light intensity and quality: 7200-8900 lux
- continuously stirred

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

15 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 4.8-46.6 mg/L

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

46.9 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 21.7-101.5 mg/L

Duration:

72 h

Dose descriptor:

EC90

Effect conc.:

146.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 33.6-641.7 mg/L

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

4.6 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

19.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 9.5-39.0 mg/L

Details on results:

no data

Results with reference substance (positive control):

no data

In the control the cell density has increased from nominal N = 1 *10⁴ cells/ml at the start of the test (0 hours) to N = 69.3 *10⁴ cells/ml (mean value) after 72 hours by a factor of approximately 69. The test substance FAT 45155/B had a statistically significant inhibition effect on the growth of Scenedesmus subspicatus first at the nominal concentration of 10.0 mg test substance/1 (= LOEC: lowest concentration tested with toxic effects). The EC 0 (= NOEC: highest concentration tested without toxic effects) after a test period of 72 hours was determined at the nominal concentration of 4.6 mg test substance/l, since in this test concentration the mean growth of algae was not significantly* lower than in control. The mean growth rate of algae after 72 hours was statistically* not significant lower than in control even up to and including the nominal test concentration of 10.0 mg test substance/l. The inhibition rate was calculated for both parameter, the algae biomass and the growth rate µ after 72 hours test duration:  

Biomass (determined as the area under the growth curve):

 

- EbC 50 (0 – 72 h): 19.3 mg test substance/l (95 % conf. limits 9.5 to 39 mg test substance/l)

- EbC 10 (0 – 72 h): 6.3 mg test substance/l (95 % conf. limits 1.9 to 20.3 mg test substance/l)

- EbC 90 (0 – 72 h): 59.2 mg test substance/l (95 % conf. limits 18.9 to185.6 mg test substance/l)

 

Growth rate µ:

 

- EµC 50 (0 – 72 h): 46.9 mg test substance/l (95 % conf. limits 21.7 to 101.5 mg test substance/l)

- EµC 10 (0 – 72 h): 15 mg test substance/l (95 % conf. limits 4.8 to 46.6 mg test substance/l)

- EµC 90 (0 – 72 h): 146.8 mg test substance/l (95 % conf. limits 33.6 to 641.7 mg test substance/l)

 

At the microscopical examination of the shape of the algal cells after 72 hours incubation period no difference was observed between the algae in the test concentration of nominal 46.3 mg test substance/l and the algal cells in the control. All test media down to the lowest test concentration were coloured by the test substance. Therefore, the observed inhibition effect of the test substance on algal growth may be caused due to a real toxic effect to the algal cells or may be caused only or in addition due to an indirect effect, a reduced light intensity or change of light quality in the coloured test media. At the start of the test, the pH-values in the test media were in the range of pH 7.7 to 7.8, at the end of the test pH-values were measured between pH 8.0 and 10.0. This strong increase of the pH-values in the control and the two lowest test concentrations was obviously caused due to the consumption of CO2 by algae during their rapid growth respectively their high densities (although the test flasks have been intensively stirred). The test substance concentrations in the analysed test media varied in the range of 84.1 to 120.5 % of the nominal values during test duration, in the sample of the stock solution 101.0 % of the nominal concentration was measured.

In the test media, incubated under test conditions (but without algae), the test substance was sufficiently stable. Therefore, all reported results are related to the nominal concentrations of the test substance.

Validity criteria fulfilled:

yes

Conclusions:

The EC50 and NOEC of FAT 45155/B based on the growth rate was 46.9 mg/L and 4.6 mg/L, respectively.

Executive summary:

In a GLP-compliant study, the influence of FAT 45155/B on the growth of the green alga Scenedesmus subspicatus Chodat was investigated in a 72-hour static test according to the guidelines OECD No. 201, and Official Journal of the European Communities, No. L 133/89-94, May 30, 1988. The nominal test concentrations were 4.6, 10.0, 21.4, 46.3 and 100.0 mg test substance/1 and a control. FAT 45155/B had a statistically significant inhibition effect on the growth of Scenedesmus subspicatus first at the nominal concentration of 10.0 mg test substance/l (= LOEC: lowest concentration tested with toxic effect). The EC 0 (= NOEC: highest concentration tested without toxic effect) was determined at 4.6 mg test substance/l, since in this test concentration the mean algal growth was not significantly lower than in control. The inhibition rate was calculated for both growth parameter, the algae biomass and the growth rate µ:

Biomass (determined as the area under the growth curve):

Biomass (determined as the area under the growth curve):

- EbC 50 (0 – 72 h): 19.3 mg test substance/l (95 % conf. limits 9.5 to 39 mg test substance/l)

- EbC 10 (0 – 72 h): 6.3 mg test substance/l (95 % conf. limits 1.9 to 20.3 mg test substance/l)

- EbC 90 (0 – 72 h): 59.2 mg test substance/l (95 % conf. limits 18.9 to185.6 mg test substance/l)

 

Growth rate µ:

- EµC 50 (0 – 72 h): 46.9 mg test substance/l (95% conf. limits 21.7 to 101.5 mg test substance/l)

- EµC 10 (0 – 72 h): 15 mg test substance/l (95% conf. limits 4.8 to 46.6 mg test substance/l)

- EµC 90 (0 – 72 h): 146.8 mg test substance/l (95% conf. limits 33.6 to 641.7 mg test substance/l)

 

All test media down to the lowest test concentration were coloured by the test substance. Therefore, the observed inhibition effect of the test substance on algal growth may be caused due to a real toxic effect to the algal cells or may be caused only or in addition due to an indirect effect, a reduced light intensity or change of light quality in the coloured test media. The test substance concentrations in the analysed test media varied in the range of 84.1 to 120.5 % of the nominal values. In the test media, incubated under test conditions (but without algae), the test substance was sufficiently stable. Therefore, all reported results are related to the nominal concentrations of the test substance. Based on the study results, the EC50 and NOEC of FAT 45155/B based on the growth rate was 46.9 mg/L and 4.6 mg/L, respectively.

Description of key information

72 h EC50 (based on growth rate) was 46.9 mg/L and the NOEC was found to be 4.6 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

46.9 mg/L

EC10 or NOEC for freshwater algae:

4.6 mg/L

Additional information

In a GLP-compliant study, the influence of FAT 45155/B on the growth of the green alga Scenedesmus subspicatus Chodat was investigated in a 72-hour static test according to the guidelines OECD No. 201. The nominal test concentrations were 4.6, 10.0, 21.4, 46.3 and 100.0 mg test substance/l and a control. FAT 45155/B had a statistically significant inhibition effect on the growth of Scenedesmus subspicatus first at the nominal concentration of 10.0 mg test substance/l (= LOEC: lowest concentration tested with toxic effect). The EC 0 (= NOEC: highest concentration tested without toxic effect) was determined at 4.6 mg test substance/l, since in this test concentration the mean algal growth was not significantly lower than in control. All test media down to the lowest test concentration were coloured by the test substance. Therefore, the observed inhibition effect of the test substance on algal growth may be caused due to a real toxic effect to the algal cells or may be caused only or in addition due to an indirect effect, a reduced light intensity or change of light quality in the coloured test media. The test substance concentrations in the analysed test media varied in the range of 84.1 to 120.5 % of the nominal values. In the test media, incubated under test conditions (but without algae), the test substance was sufficiently stable. Therefore, all reported results are related to the nominal concentrations of the test substance. Based on the study results, the EC50 and NOEC of FAT 45155/B based on the growth rate was 46.9 mg/L and 4.6 mg/L, respectively.