Sodium 3-[[3-methoxy-4-[(4-methoxyphenyl)azo]phenyl]azo]benzenesulphonate

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:

Study initiation date - 20 August 1990; Experiment start date - 03 December 1990; Experiment end date - 11 January 1991; Study completion date - 25 February 1991.

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: Draft International Standard ISO/TC 147: "Water quality - Algal growth inhibition test, submitted June 25, 1987.

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Name: FAT 20004/H
Batch No: EN 317
Expiration Date: June 1995

Analytical monitoring:

yes

Details on sampling:

Analyses of the test substance were performed in duplicate in a sample of the stock solution and of test media of the nominal test concentrations 0.6, 2.5, and 10.0 mg/l mg test substance/l and the solvent control: a part of the freshly prepared stock solution and test media (without algae) were sampled and analysed.
For the determination of the stability of the test substance under test conditions, a part of the test media were incubated under the same conditions as in the test itself (but without algae) and analysed after the end of the test (96 hours). All samples will be kept stored at -20 °C until delivery of the final test report, pending on the decision of the sponsor for additional analyses.

Vehicle:

not specified

Details on test solutions:

A stock solution was prepared by dissolving the test substance in Dimethylformamide p.A. (100 g/l). The stock solution was diluted in a series of sequential dilutions with the solvent to add the same volumes of solvent (0.1 ml/l) to each test solution. The final nominal concentrations of FAT 20004/H in the test media were: 0.6, 1.3, 2.5, 5.0 and 10.0 mg/l, a control without any additions and a solvent control (100 µl Dimethylformamide/l test medium).

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Strain: Strain No. 8681 SAG
- Source (laboratory, culture collection): supplied by the Sammlung von Algenkulturen, Pflanzenphysiologisches Institut der Universität Göttingen, D-3400 Göttingen, F.R.G. The algae were grown in the laboratories of RCC under standardized conditions according to the OECD Guideline No. 201

Test type:

static

Water media type:

freshwater

Limit test:

no

Post exposure observation period:

72 hours

Test temperature:

21.3 to 23.4 °C

pH:

7.9 to 10.3

Nominal and measured concentrations:

The final nominal concentrations of FAT 20004/H in the test media were: 0.6, 1.3, 2.5, 5.0 and 10.0 mg/l, a control without any additions and a solvent control.

Details on test conditions:

Experimental Conditions
The algae were cultivated and tested in a test solution prepared according to the OECD Guideline No. 201.The experiment was started (0 hours) with a biomass of nominal 10,000 cells per ml test solution. These cells were taken from a sterile pre-culture, which was set up 72 hours prior to the test at the same conditions as in the test. Per test concentration, 150 ml of test solution (sterile nutrient solution, dissolved test substance and algae suspension) was incubated on a laboratory shaker in an air-conditioned room and by continuous illumination at 8000 Lux (±20 %) . This illumination was achieved by fluorescent tubes (universal white L 25, 36 W) , installed above the shaker in a distance of about 40 cm from the algae flasks. Incubation flasks used were 250 ml Erlenmeyer flasks stoppered with permeable plugs. The test design included three replicates of each test concentration and twice that number of controls. The test duration was 96 hours. As a means of detecting unsatisfactory test conditions the reference substance Potassium Dichromate p.A. has been periodically tested (twice a year).

Reference substance (positive control):

not required

Duration:

72 h

Dose descriptor:

EC0

Effect conc.:

5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Details on results:

In the control the cell density has increased from nominal N = 1 x 10E4 cells/ml at the start of the test (0 hours) to N = 304.4 x10E4 cells/ml after 96 hours by a factor of about 304, in the solvent control this factor amounted to about 27 8.8.

FAT 20004/H has obviously only a low inhibition effect on the growth of Scenedesmus subspicatus: first in the highest concentration tested of 10.0 mg test substance/l a marked reduction of cell densities and algae biomass (determined as the area under the growth curve) in relation to the solvent control was observed after 7 2 and 96 hours test duration, but for the growth rate u no clear concentration-effect-relation was observed up to this concentration. Therefore, the EC 0 (= NOEC: highest concentration tested without toxic effect) was determined to be 5.0 mg test substance/l, the LOEC (lowest concentration tested with toxic effect) amounted to 10.0 mg test substance/l. Due to the low inhibition rate in the concentration of 10 mg/l (as the highest concentration as possible to dissolve in Dimethyl formamid p.A at room temperature and an addition of 100 µl solvent stock solution to 1:1 test medium) no EC 50-values could be calculated.

Validity criteria fulfilled:

yes

Conclusions:

The EC0 was determined to be 5.0 mg test substance/L and the LOEC was determined to be 10.0 mg test substance/L.

Executive summary:

The influence of FAT 20004/H on the growth of the green alga Scenedesmus subspicatus Chodat was investigated in a 96-hour static test according to the OECD Guideline No. 201, adopted June 7, 1984 and the Draft ISO/TC 147, submitted June 25, 1987. The nominal concentrations tested were 0.6, 1.3, 2.5, 5.0 and 10.0 mg test substance/l , a control without any additions and a solvent control group. FAT 20004/H had low inhibition effect on the growth of Scenedesmus subspicatus. In the highest concentration tested of 10.0 mg test substance/L a marked reduction of cell densities and algae biomass (determined as the area under the growth curve) in relation to the solvent control was observed after 72 and 96 hours test duration, but for the growth rate no clear concentration-effect-relation was observed up to this concentration. Therefore, the EC0 (= NOEC: highest concentration tested without toxic effect) was determined to be 5.0 mg test substance/l, the LOEC (lowest concentration tested with toxic effect) amounted to 10.0 mg test substance/l. Due to the low inhibition rate in the concentration of 10 mg/l no EC 50-values could be calculated. The test substance concentrations in the analysed test media amounted to 80 - 93.5 % of the nominal values. In the test media, incubated under test conditions (but without algae), the test substance was sufficiently stable. Therefore, the reported results are related to the nominal concentration of the test substance. The EC0 was determined to be 5.0 mg test substance/L and the LOEC amounted to 10.0 mg test substance/L.

Description of key information

The EC0 was determined to be 5.0 mg test substance/L and the LOEC amounted to 10.0 mg test substance/L. Hence, the LC50 is concluded to be greater than 100mg/L.

Additional information

The influence of FAT 20004/H on the growth of the green alga Scenedesmus subspicatus Chodat was investigated in a 96-hour static test according to the OECD Guideline No. 201, adopted June 7, 1984 and the Draft ISO/TC 147, submitted June 25, 1987. The nominal concentrations tested were 0.6, 1.3, 2.5, 5.0 and 10.0 mg test substance/l, a control without any additions and a solvent control group. FAT 20004/H had low inhibition effect on the growth of Scenedesmus subspicatus. In the highest concentration tested of 10.0 mg test substance/L a marked reduction of cell densities and algae biomass (determined as the area under the growth curve) in relation to the solvent control was observed after 72 and 96 hours test duration, but for the growth rate no clear concentration-effect-relation was observed up to this concentration. Therefore, the EC0 (= NOEC: highest concentration tested without toxic effect) was determined to be 5.0 mg test substance/l, the LOEC (lowest concentration tested with toxic effect) amounted to 10.0 mg test substance/l. Due to the low inhibition rate in the concentration of 10 mg/l no EC 50-values could be calculated. The test substance concentrations in the analysed test media amounted to 80 - 93.5 % of the nominal values. In the test media, incubated under test conditions (but without algae), the test substance was sufficiently stable. Therefore, the reported results are related to the nominal concentration of the test substance. The EC0 was determined to be 5.0 mg test substance/L and the LOEC amounted to 10.0 mg test substance/L.