Tetrasodium 3,3'-[[6-[(2-hydroxyethyl)amino]-1,3,5-triazine-2,4-diyl]bis[imino(2-methyl-4,1-phenylene)azo]]bisnaphthalene-1,5-disulphonate

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1990

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods

Qualifier:

according to guideline

Guideline:

ISO 8192 (Water quality - Test for inhibition of oxygen consumption by activated sludge for carbonaceous and ammonium oxidation)

Version / remarks:

1986

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Direct weighings were used to prepare the different test item concentrations.
- Controls: For the reference compound a stock solution at a concentration of 500 mg/L
was prepared by dissolving 500 mg 3.5-Dichlorophenol in 10 ml of 1 M NaOH
and diluting to 1 litre with deionised water. The pH was adjusted to pH 7±0.5
with H2S04

Test organisms (species):

activated sludge of a predominantly industrial sewage

Details on inoculum:

- Laboratory culture: aboratory scale sewage treatment unit (3L), treating predominantly industrial sewage.
- Name and location of sewage treatment plant where inoculum was collected: Leverkusen Bürrig I Germany
- Preparation of inoculum for exposure:
- first, the sludge was settled and the supernatant was decanted, - after centrifuging (20 min at 4000 rpm and 20°C) the supernatant was decanted, - approx. 1 g of the wet sludge was dried in order to calculate the amount of sludge to achieve a concentration of activated sludge of 6 g/1 (dry weight) suspended solids, - the calculated amount of sludge was first dissolved in synthetic medium and than filled up to a defined end volume with deionised water, - Storage of sludge: aeration of the activated sludge at 20°c ± 2°C, daily fed with synthetic medium
- Initial biomass concentration: 6 g/L dry weight

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Hardness:

no data

Test temperature:

20.4 - 20.9

pH:

7.1 - 7.9

Dissolved oxygen:

10000 mg/L test concentration: 5.3 (mg 02/L) at start , 2.3 (mg 02/L) at end

Salinity:

no data

Conductivity:

no data

Nominal and measured concentrations:

100, 1000 and 10000 mg/L (nominal)

Details on test conditions:

TEST SYSTEM
- Test vessel: 300 ml glass Erlenmeyer flasks
- Aeration: 3 hours with permanent aeration
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 2 (1 at start and 1 at end)
- No. of vessels per oxygen consumption (replicates):1
- Sludge concentration (weight of dry solids per volume): 6 g/L dry weight

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: A synthetic waste water feed was made by
dissolving the following amounts of substance in 1 litre of water.
16.0 g peptone
11.0 g meat extract
3.0 g urea
0.7 g NaCI
0.4 g CaCI2 x 2H20
0.2 g MgS04 X 7H20
2.8 g K2HP04

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Oxygen consumption, temperature and ph were measured after an aeration time of 3 hours

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 10 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Results with reference substance (positive control):

Concentration: 1 and 20 mg/L
Inhibition: 0 at 1 mg/L, 69.2 at 20 mg/L

Validity criteria fulfilled:

yes

Remarks:

(respiratory rates of the 2 controls differ less than 15%, ECso of the reference compound 3,5-Dichlorophenol is in the range 5- 30 mg/L)

Conclusions:

Bayscript Gelb BR showed 1. 7% respiration inhibition of activated sludge at the highest test item concentration of 10000 mg/L. The ECso:was > 10000 mg/L.

Executive summary:

To assess the toxicity of Bayscript Gelb BR to bacteria a study was conducted in accordance with ISO 8192-1986/B "Activated sludge respiration inhibition" (1986). This test method is equal to OECD Guideline 209 (1984). The activated sludge was exposed to Bayscript Gelb BR at different concentrations (100, 1000, 10000 mg/L). The respiration rate of each mixture was determined after aeration periods of 3 hours.

Before use the pH of the activated sludge was measured and adjusted to pH 6-8. 8 ml of the synthetic medium and 25 ml of activated sludge were added to the dissolved test item. The mixture was filled up with deionised water to 250 ml and aerated at 20°C ± 2°C. The exposure medium with the reference substance was prepared by adding 8 ml of the synthetic medium, 25 ml of activated sludge and a defined amount of the stock solution to achieve the test concentrations and was filled up to 250 ml with

deionised water. Oxygen consumption was measured and recorded after an aeration time of 3 hours. Thereafter, temperature and pH of the exposure medium were measured. A control at test start and end (control 1, 2) was tested in the same way. The exposure medium to determine the physico-chemical oxygen consumption was prepared as the medium with the test item, but without activated sludge.

Bayscript Gelb BR showed 1.7% respiration inhibition of activated sludge at a test item concentration of 1 0000 mg/L. The ECso is > 10000 mg/L. The effect value related to nominal concentration, since no analytical monitoring was performed.

Description of key information

Bayscript Gelb BR showed 1. 7% respiration inhibition of activated sludge at the highest test item concentration of 10000 mg/L. The EC50 was > 10000 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:

10 000 mg/L

Additional information

should read > 10000 mg/L