tetrasodium 3-amino-4-{[4-({4-fluoro-6-[phenyl(2-{[2-(sulfonatooxy)ethyl]sulfonyl}ethyl)amino]-1,3,5-triazin-2-yl}amino)-2-sulfonatophenyl]diazenyl}-5-hydroxynaphthalene-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:

From Nov. 08, 2004 to Nov. 10, 2004

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Type: mixed population of aquatic microorganisms (activated sludge).
- Origin: aeration tank of a domestic sewage treatment plant (Wupper area water authority).
- Pretreatment: aeration of the activated sludge; daily feed with synthetic medium.
- pH of the suspension before application: 7.1

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

19.2-19.5 °C (control),
19.2-19.3 °C (test groups),
19.3 °C (physicochemical oxygen consumtion control),
18.6-19.2 °C (reference substance).

pH:

7.6-7.8 (control),
7.8-7.9 (test groups),
7.1 (physicochemical oxygen consumtion control),
7.7-8.0 (reference substance).

Dissolved oxygen:

Control:
Start = 5.0-5.4 mg/L; End = 2.9-3.3 mg/L

Test:
Start = 5.1-5.8 mg/L; End = 2.6-3.1 mg/L

Physicochemical oxygen consumtion control:
Start = 8.5 mg/L; End = 8.5 mg/L

Reference substance:
Start = 5.5-7.9 mg/L; End = 2.7-7.6 mg/L

Nominal and measured concentrations:

- Test concentrations (nominal): 100, 1000 and 10,000 mg/L
- Test substance concentration in physico-chemical oxygen consumption control (nominal): 10,000 mg/L
- Concentration of reference substance '3,5-dichlorophenol' (nominal): 5, 10 and 20 mg/L

Details on test conditions:

- Test concentration of the activated sludge: 480 mg/L suspended solids
- Incubation: 3 h with permanent aeration

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol (97% purity; Batch number: I5809KI-392)

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:

EC10

Effect conc.:

> 10 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Results with reference substance (positive control):

- EC50 for reference substance = 8.1 mg/L

Reported statistics and error estimates:

The EC50 value was determined by probit analysis.

Table 1: Inhibition of respiration

Treatment group	Concentration [mg/L]	Respiratory rate mg/[L×h]	% inhibition of respiration
Control	-	42.0	-
Test substance	100	45.0*	0.0
Test substance	1,000	42.0*	0.0
Test substance	10,000	40.0*	4.8
Reference substance (3, 5 dichlorophenol)	5	33.6	20.0
Reference substance (3, 5 dichlorophenol)	10	14.0	66.7
Reference substance (3, 5 dichlorophenol)	20	3.6	91.4

* The physico-chemical oxygen consumption was been detennined at 10,000 mg/L test substance concentration. As no physico-chemical oxygen consumption was observed at that test item concentration this observation also holds true for the lower test item concentrations.

Validity criteria fulfilled:

yes

Conclusions:

Under the test conditions, the EC10 of the test substance was >10000 mg/L, indicating a low toxicity to microorganisms.

Executive summary:

A study was conducted to assess the toxicity of the test substance to sludge microorganisms, according to EU Method C.11 (similar to OECD Guideline 209), in compliance with GLP.

Activated sludge from domestic sewage was exposed to nominal test substance concentrations of 100, 1000 and 10,000 mg/L. The respiration rates of each of these mixtures was determined after an aeration period of 3 h and compared to data from the control and the reference substance 3,5-dichlorophenol.

The reference substance produced 20.0, 66.7 and 91.4% inhibition of respiration at 5, 10 and 20 mg/L respectively. The test substance produced 0.0, 0.0 and 4.8% inhibition of respiration at concentrations of 100, 1000 and 10000 mg/L respectively.

Under the test conditions, the EC10 of the test substance was >10000 mg/L, indicating a low toxicity to microorganisms.

Description of key information

The 3-h EC10 of the test substance was >10000 mg/L, indicating a low toxicity to microorganisms.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

10 000 mg/L

Additional information

A study was conducted to assess the toxicity of the test substance to sludge microorganisms according to EU Method C.11 (similar to OECD Guideline 209), in compliance with GLP. Activated sludge from domestic sewage was exposed to nominal concentrations of 100, 1,000 and 10,000 mg/L. The respiration rates of each of these mixtures was determined after an aeration period of 3 h and compared to data from the control and the reference substance 3,5-dichlorophenol. The reference substance produced 20.0, 66.7 and 91.4% inhibition of respiration at 5, 10 and 20 mg/L respectively. The test substance produced 0.0, 0.0 and 4.8% inhibition of respiration at concentrations of 100, 1,000 and 10,000 mg/L respectively. Under the test conditions, the EC10 of the test substance was >10000 mg/L, indicating a low toxicity to microorganisms (Bruns, 2004).