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
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
according to guideline
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Version / remarks:
ISO 8192-1986/B
Principles of method if other than guideline:
The method assessed the effect of a test item on microorganisms by measuring the respiration rate under defined conditions in the presence of different concentrations of the test item.
GLP compliance:
yes
Specific details on test material used for the study:
Batch No., charge and purity not reported.
Analytical monitoring:
no
Remarks:
The effect value related to nominal concentration, since no analytical monitoring was performed.
Vehicle:
not specified
Details on test solutions:
A synthetic waste water feed was made by dissolving the following amounts of substance in 1 litre of water:
16.0 g peptone
11.0 g meat extract
3.0 g urea
0.7 g NaCl
0.4 g CaCl2 x 2H2O
0.2 g MgSO4 x 7H2O
2.8 g K2HPO4
Before use the pH of the activated sludge was measured and adjusted to pH 6-8. 8 mL of the synthetic medium and 25 mL of activated sludge were added to the dissolved test item. The mixture was filled up with deionised water to 250 mL and aerated at 20°C ± 2°C.
Test organisms (species):
activated sludge
Details on inoculum:
Type: mixed population of aquatic microorganisms
Origin: laboratory scale sewage treatment unit (3l), treating predominantly industrial sewage. (Location: Bürrig / Germany)
Sampling of the sludge: 24.11.1989
Concentration of the activated sludge: 6.00 g/L
Actuallly applied quantity: 150.000 g/2L
Preparation:
- first, the sludge was settled and the supernatant
was decanted
- after centrifuging (20 min at 4000 rpm and 20°C)
the supernatant was decanted
- approx. 1 g of the wet sludge was dried in order
to calculate the amount of sludge to achieve
a concentration of activated sludge of 6 g/l (dry
weight) suspended solids
- the calculated amount of sludge was first
dissolved in synthetic medium and than filled up
to a defined end volume with deionised water
Storage of sludge: aeration of the activated sludge at 20°C ± 2°C, daily fed with synthetic medium
Test type:
not specified
Water media type:
other: A synthetic waste water feed was made in 1 litre of water.
Total exposure duration:
3 h
Remarks on exposure duration:
Incubation time with permanent aeration
Test temperature:
19.8 - 20.4 °C
pH:
8.0 - 8.4
Dissolved oxygen:
5.70 - 9.30 mg (Start)
3.00 - 9.00 mg (End)
Nominal and measured concentrations:
Test item concentration/s: 100, 1000 and 10000 mg/L (nominal)
Test item concentration in physico-chemical oxygen consumption control: 10000 mg/L (nominal)
Concentration of reference compound 3.5-Dichlorophenol: 1 and 20 mg/L (nominal)
Details on test conditions:
Before use the pH of the activated sludge was measured and adjusted to pH 6-8. Test system was was filled up with deionised water and aerated at 20°C ± 2°C.
Reference substance (positive control):
yes
Remarks:
Two controls without test item were included in the test design, one at the start and the other at the end of the test series. Each batch of activated sludge was checked using 3,5-Dichlorophenol as a reference compound.
Duration:
3 h
Dose descriptor:
other: EC5
Effect conc.:
20.806 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Duration:
3 h
Dose descriptor:
EC10
Effect conc.:
27.856 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Key result
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
77.953 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Duration:
3 h
Dose descriptor:
other: EC90
Effect conc.:
218.173 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Duration:
3 h
Dose descriptor:
other: EC95
Effect conc.:
292.106 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Details on results:
The respiration rate for each concentration was determined graphically from the linear part of the curve of O2-content versus time. The inhibitory effect of the test item at a particular concentration is expressed as a percentage of the mean of the respiration rates of two controls.
Results with reference substance (positive control):
EC50 of the reference compound 3,5-Dichlorophenol is in the range 5 – 30 mg/L.
Reported statistics and error estimates:
Confidence limits could not be calculated.
Validity criteria fulfilled:
yes
Remarks:
Respiratory rates of the 2 controls differ less than 15 %.
Conclusions:
EC50 of the test substance Vulkacit P extra N was determined at a concentration of 78 mg/L.
Executive summary:

The study was conducted in accordance with ISO 8192-1986/B ”Activated sludge respiration inhibition” (1986). This test method is equal to OECD Guideline 209 (1984). The method assessed the effect of a test item on microorganisms by measuring the respiration rate under defined conditions. The activated sludge was exposed to Vulkacit P extra N at different concentrations. The respiration rate of each mixture was determined after aeration periods of 3 hours. Vulkacit P extra N showed an EC50 of 78 mg/L (nominal concentration).

Description of key information

The study was conducted in accordance with ISO 8192-1986/B ”Activated sludge respiration inhibition” (1986). This test method is equal to OECD Guideline 209 (1984). The method assessed the effect of a test item on microorganisms by measuring the respiration rate under defined conditions. The activated sludge was exposed to Vulkacit P extra N at different concentrations. The respiration rate of each mixture was determined after aeration periods of 3 hours. Vulkacit P extra N showed an EC50 of 78 mg/L (nominal concentration).

Key value for chemical safety assessment

EC50 for microorganisms:
78 mg/L

Additional information