reaction mass of: tetrasodium 4-amino-6-(5-(2,6-difluoropyrimidin-4-ylamino)-2-sulfonatophenylazo)-5-hydroxy-3-(4-(sulfatoethylsulfonyl)phenylazo)naphthalene-2,7-disulfonate;tetrasodium 4-amino-6-(5-(4,6-difluoropyrimidin-2-ylamino)-2-sulfonatophenylazo)-5-hydroxy-3-(4-(2-sulfatoethylsulfonyl)phenylazo)naphthalene-2,7-disulfonate

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:

1998-03-03 to 1998-04-17

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Version / remarks:

87/302/EWG, S. 118; OECD 209

Qualifier:

according to guideline

Guideline:

other: 88/302/EEC Part C

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Direct weighing
- Incubation time: 3 h with permanent aeration

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Activated sludge concentration: 480 mg/L. This concentration was used due to a strong respiration rate
- Details of source: aeration tank of a waste water plant treating predominantly domestic sewage (Wupper area water authority)
- Method of cultivation: Mixed population of different microorganisms
- Pre-treatment: None
- pH before application: 7.4

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

None

Test temperature:

18.5-18.8 °C in test substance and control vessels

pH:

Test solution: 8.0-8.2
Controls: 8.2
Abiotic control: 7.5

Dissolved oxygen:

At test start:
Test solution: 4.7-5.9 mg/L
Controls: 5.7-5.8 mg/L
Abiotic control: 8.8 mg/L

Salinity:

N/A

Nominal and measured concentrations:

Test vessels: 100, 1000, 10000 mg/L
Physico-chemical oxygen consumption controls: 10000 mg/L
Controls: 0 mg/L

Details on test conditions:

Type of application: Direct weighing
Test concentration of the activated sludge: 400 mg/L suspended solids

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:

inhibition of total respiration

Remarks:

respiration rate

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

3.4 % respiration inhibition of activated sludge was observed at the highest test substance concentration of 10000 mg/L.
No inhibition of respiration was shown at other concentrations.

Results with reference substance (positive control):

- Reference compound 3.5-dichlorophenol
- Results with reference substance valid: Yes
- Ref. concentrations: 5, 10, 20 mg/L
- % Inhibition: 17.2, 48.3 and 80.9 % inhibition at 5, 10 and 20 mg/L, respectively
- EC50: 10 mg/L

Reported statistics and error estimates:

The EC values were determined by statistical methods (probit analysis).

Test concentration [mg/L]	Respiratory rate test substance[mg/L/h]	Phys.chem. O2-consumption [mg/L/h]	Respiratory rate – phys.chem. O2 –consumption [mg/L/h]	Inhibition [%]
100	45.0	0.0*	45.0	0.0
1000	43.5	0.0*	43.5	0.0
10000	42.0	0.0	42.0	3.4
Control, mean	43.5
Control 1	45.0
Control 2	42.0

Validity criteria fulfilled:

yes

Conclusions:

Under conditions employed, the test substance showed 3.4 % respiration inhibition to activated sludge at a concentration of 10000 mg/L. The EC10 was determined to be > 10000 mg/L.

Executive summary:

A study was performed to assess the toxicity of the test substance to bacteria, according to Commission Directive 88/302/EEC (Official Journal of the EC L133 Part C (1988)), which is largely equivalent to OECD guideline 209, in compliance with GLP.

The activated sludge was exposed to the test substance at different concentrations. The respiration rate of each mixture was determined after an aeration period of 3 h. The test substance showed 3.4 % respiration inhibition to activated sludge at a concentration of 10,000 mg/L. The NOEC of Reactive Navy FC63805 was determined to be ≥ 10,000 mg/L. An EC50 of the test substance could not be determined; however a hypothetical EC50 value would be > 10,000 mg/L.

Description of key information

Under conditions of a respiration inhibition test, Reactive Navy FC63805 showed 3.4 % inhibition of the activated sludge microorganisms at a concentration of 10,000 mg/L. An EC50 cannot be determined. The NOEC was identified at 1.000 mg/L.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

10 000 mg/L

Additional information

A study was performed to assess the toxicity of test substance to bacteria according to Commission Directive 88/302/EEC (Official Journal of the EC L133 Part C (1988)), similar to OECD guideline 209, in compliance with GLP.

The activated sludge was exposed to the test substance at different concentrations. The respiration rate of each mixture was determined after an aeration period of 3 h. The test substance showed 3.4 % respiration inhibition of activated sludge at the highest test concentration of 10000 mg/L. The EC10 and EC50 of the test substance are >10000 mg/L. The inhibition of the reference substance demonstrated the validity of the test.