REAKTIVE GELB F 97494

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 January 14, 2002 to January 17, 2002

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: 88/302/EEC, L 133 Part C

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

yes

Details on test solutions:

The test substance was added to about 130 mL deionized water and stirred overnight before testing (equilibration phase).

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 waste water treatment plant treating predominantly domestic sewage (Wupper area water authority).
- Pretreatment: aeration of the activated sludge; daily feed with synthetic medium.
- pH of the suspension before application: 7.3

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Remarks on exposure duration:

with permanent aeration

Test temperature:

19.1-19.3°C

pH:

Test: 8.2-8.4

Dissolved oxygen:

Control:
Start = 6.2-6.3; End = 2.9-3.1

Reference substance:
Start = 6.4-7.8; End = 2.7-6.4

Test:
Start = 5.3-6.2; End = 2.7-3.6

Nominal and measured concentrations:

- Type of test material application: direct weighing
- 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: 520 mg/L suspended solids (this concentration was selected on the basis of strong respiration of the activated sludge).

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

Details on results:

Refer to table 1 under 'Any other information on results incl. tables'.

Results with reference substance (positive control):

Refer to table 1 under 'Any other information on results incl. tables'.

Reported statistics and error estimates:

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

Table 1: Inhibition of respiration:

Treatment group	Concentration [mg/L]	Respiratory rate mg/[L×h]	% inhibition of respiration
Control	-	39	-
Test substance	100	36	7.7
Test substance	1,000	39	0.0
Test substance	10,000	36	7.7
Reference substance (3, 5 dichlorophenol)	5	31.7	18.7
Reference substance (3, 5 dichlorophenol)	10	27.4	29.7
Reference substance (3, 5 dichlorophenol)	20	10.5	73.1

 

Validity criteria fulfilled:

yes

Conclusions:

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

Executive summary:

A study was performed to assess the toxicity of the test substance to sludge microorganisms. The study was conducted in accordance with Guideline 88/302/EEC, L 133 Part C, in compliance with GLP.

Activated sludge from domestic sewage was exposed to nominal concentrations of 0,100, 1000 and 10,000 mg/L for a period of 3 h. The respiration rates of each of these mixture were 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 3,5 -dichlorophenol produced 18.7, 29.7 and 73.1% respiration inhibition at 5, 10 and 20 mg/L, respectively. The test substance produced 7.7, 0.0 and 7.7% respiration inhibition at 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.

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.

Key value for chemical safety assessment

EC50 for microorganisms:

10 000 mg/L

EC10 or NOEC for microorganisms:

10 000 mg/L

Additional information

A study was performed to assess the toxicity of the test substance to sludge microorganisms. The study was conducted in accordance with Guideline 88/302/EEC, L 133 Part C, in compliance with GLP. Activated sludge from domestic sewage was exposed to nominal concentrations of 0,100, 1000 and 10,000 mg/L for a period of 3 h. The respiration rates of each of these mixture were 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 3,5 -dichlorophenol produced 18.7, 29.7 and 73.1% respiration inhibition at 5, 10 and 20 mg/L, respectively. The test substance produced 7.7, 0.0 and 7.7% respiration inhibition at 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.