tetrasodium 2-(4-fluoro-6-(methyl-(2-(sulfatoethylsulfonyl)ethyl)amino)-1,3,5-triazin-2-ylamino)-5-hydroxy-6-(4-methyl-2-sulfonatophenylazo)naphthalene-1,7-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 June 21, 1999 to June 22, 1999

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

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

Type: Activated sludge (mixed population of different microorganisms)
Origin: Aeration tank of a waste water plant treating predominantly domestic sewage (Wupper area water authority)
Pretreatment: None
pH of the suspension before application: 6.8

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

20±2° C

pH:

7.1-8.0

Dissolved oxygen:

Control:
Start = 6.2-6.3 mg/L; End = 2.6-2.8 mg/L

Reference substance:
Start = 6.2-8.0 mg/L; End = 3.7-7.2 mg/L

Test:
Start = 5.9-6.3 mg/L; End = 2.7-3.8 mg/L

Nominal and measured concentrations:

The test substance was added to about 130 mL of deionized water and stirred overnight before testing (equilibration phase). The study was carried out with nominal weights. The test concentrations were not confirmed by chemical analysis.

- 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:

- Type of application: direct weighing
- Test concentration of the activated sludge: 480 mg/L (concentration based on strong respiration of the activated sludge)

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol (97% purity)

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

Results with reference substance (positive control):

- EC50 for reference substance = 9.8 mg/L

Reported statistics and error estimates:

The EC50 values were determined by probit analysis.

Table 1: Inhibition of respiration:

 

Treatment group	Concentration [mg/L]	Respiratory rate mg/[L×h]	% inhibition of respiration
Control	-	26.7	-
Test substance	100	28.3*	0.0
Test substance	1,000	27.4*	0.0
Test substance	10,000	21.4*	19.9
Reference substance (3, 5 dichlorophenol)	5	21.4	19.9
Reference substance (3, 5 dichlorophenol)	10	12.0	55.1
Reference substance (3, 5 dichlorophenol)	20	6.0	77.5

 

* Physico-chemical oxygen consumption corrected respiration rate. No physico-chemical oxygen consumption was observed at the test substance concentration of 10,000 mg/L.

Validity criteria fulfilled:

yes

Conclusions:

Under the test conditions, the EC50 of the test substance was >10,000 mg/L, indicating a low toxicity to microorganisms. The NOEC was 1,000 mg/L.

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 the mixture 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 19.9, 55.1 and 77.5% inhibition of respiration at 5, 10 and 20 mg/L respectively. The test substance produced 0, 0 and 19.9% inhibition of respiration at concentrations of 100, 1000 and 10,000 mg/L respectively.

Under the test conditions, the EC50 of the test substance was >10,000 mg/L, indicating a low toxicity to microorganisms. The NOEC was 1,000 mg/L.

Description of key information

Under the test conditions, the EC50 of the test substance was >10,000 mg/L, indicating a low toxicity to microorganisms. The NOEC was 1,000 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:

10 000 mg/L

EC10 or NOEC for microorganisms:

1 000 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 test substance concentrations of 100, 1000 and 10,000 mg/L. The respiration rates of each of the mixture 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 19.9, 55.1 and 77.5% inhibition of respiration at 5, 10 and 20 mg/L respectively. The test substance produced 0, 0 and 19.9% inhibition of respiration at concentrations of 100, 1000 and 10,000 mg/L respectively. Under the test conditions, the EC50 of the test substance was >10,000 mg/L, indicating a low toxicity to microorganisms. The NOEC was 1,000 mg/L.