Registration Dossier

Ecotoxicological information

Toxicity to microorganisms

Currently viewing:

Administrative data

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:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Version / remarks:
87/302/EWG, S. 118; OECD 209
Qualifier:
according to
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.