Registration Dossier

Administrative data

Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
1998-09-07 till 1998-09-08
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study without restrictions.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1998
Report Date:
1998

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
other: Commission Directive 88/302/EEC; Official Journal of the EC L 133 , Part C: Biodegradability: Test for inhibition of oxygen consumption
Deviations:
no
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Deviations:
no
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Type:
Constituent
Test material form:
other: solid
Details on test material:
- Purity: 58.3 %
- Empirical formula: C25H32FN3O4S
- Molecular mass: 489.2 g/mole

Sampling and analysis

Analytical monitoring:
no

Test solutions

Vehicle:
no
Details on test solutions:
Direct weighings were prepared to give the different test item concentrations. The test item was added into Erlenmeyer flasks (incubation vessels) to about 130 mL deionised water and was stirred overnight.

Test organisms

Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
- mixed population of different microorganisms, origin of an aeration tank of a waste water plant treating predominantly domestic sewage (Wupper
area water authority)
- pH: 6.8
- test concentration of the activated slugde: 480 mg/L

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h

Test conditions

Hardness:
no data
Test temperature:
18.6 - 20.9 °C (including all test concentrations, controls and reference substance)
pH:
7.3 - 8.1 (including all test concentrations, controls and reference substance)
Dissolved oxygen:
Test substance: 6.0 - 9.5 mg O2/L at the beginning of the test and 2.5 - 8.8 mg O2/L at the end of the test.
Reference substance: 6.3 - 9.7 mg O2/L at the beginning of the test and 3.1 - 9.2 mg O2/L at the end of the test.
Control: 6.1 mg O2/L at the beginning of the test and 2.8 - 3.0 mg O2/L at the end of the test.
Physico-chemical of oxygen consumption control: 9.5 mg O2/L.
Nominal and measured concentrations:
- nominal concentration of the test substance: 1000, 1800, 3200, 5600 and 10000 mg/L
- nominal concentration of the reference substance: 2.5, 5, 10, 20 and 40 mg/L
Details on test conditions:
Test system:
- 300 mL glass Erlenmeyer flasks
- type of applcation: direct weighing
- test concentration of the actived sludge: 480 mg/L suspended solids
- temperature: 20 ± 2 °C
- stirring period before start of incubation: overnight
- two controls without test substance at test start and test end were performed in presence of activated sludge
- one physico-chemical oxygen consumption control was carried out at the highest test concentration od 10000 mg/L
Reference substance (positive control):
yes
Remarks:
3,5-Dichlorophenol, purity: 97 % (Aldrich)

Results and discussion

Effect concentrations
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
4 950 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 of the reference substance 3,5-dichlorophenol is in the range 5 - 20 mg/L.
Inhibition: at 2.5 mg/L 12.8 %, at 5 mg/L 23.1 %, at 10 mg/L 50.0 %, at 20 % at 82.3 % and at 40 mg/L 89.0 %.

Any other information on results incl. tables

Results:

 Test concentration  Respiratory rate  Phys. chem.  Respiratory rate  Inhibition
   test substance  O2 -cunsumption  phys. chem. O2 -consumption  
 [mg/L]  [mg/L*h]  [mg/L*h]  [mg/L*h]  [%]
1000   38.4  0.0  38.4  1.5
 1800  35.0  0.0  35.0  10.3
 3200  31.7  0.0  31.7  18.7
 5600  16.3  0.0  16.3  58.2
 10000  5.3  0.0  5.3  86.4
 Control, mean 39.0      
 Control 1  37.2      
 Control 2  40.8      

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
(-respiratory rates of the two controls differ less than 15 %. - the EC50 of the reference compound 3,5-Dichlorophenol is in the range 5 - 20 mg/L.)
Conclusions:
The test item showed 18.7 % respiration inhibition of activated slugde at a test concentration of 3200 mg/L and 58.2 % of 5600 mg/L. An EC50 of 4950 mg/L was calculated. The effect value relates to nominal concentration; since no analytical monitoring was performed.
Executive summary:

In order to test the toxicity to microorganisms of the substance, activated sludge from predominantly domestic sewage plant was exposed to the test solution of five nominal concentrations of the substance (1000, 1800, 3200, 5600 and 10000 mg/L), blank control solution and solution with positive reference substance for a period of 3 hours. Dissolved oxygen was recorded and respirationrates were calculated. No physico-chemical oxygen consumption was observed at the highest concentration of test substance.

The test item showed 18.7 % respiration inhibition of activated slugde at a test concentration of 3200 mg/L and 58.2 % of 5600 mg/L. An EC50 of 4950 mg/L was calculated. The effect value relates to nominal concentration; since no analytical monitoring was performed.

This toxicity study is classified as acceptable and satisfies the guideline requirements for the toxicity study to microorganisms.