Registration Dossier

Administrative data

Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1998-03-26
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study

Data source

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

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)
Version / remarks:
Cited as Directive 87/302/EEC, part C, p. 118 (Biodegradation: Activated sludge respiration inhibition test)
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Test substance: (Z,Z)-1,5-cyclooctadiene of Hüls AG, purity 99.6% (GC)
Batch No. B 803 of 10 Oct. 1997
Sample No. 1672/971103, Sample ID 0637/81865

Sampling and analysis

Analytical monitoring:
no

Test solutions

Vehicle:
no
Details on test solutions:
STOCK AND TEST SOLUTION AND THEIR PREPARATION
- Dispersion: direct addition of calculated volumes (assumed density 0.88  g/ml); no stock solution, no vehicle or solvent.

Test organisms

Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
TEST ORGANISMS
- Strain: Activated sludge (mixed culture)
- Source/supplier: Predominantly domestic municipal STP Marl-West;   
5 l activated sludge sampled; settling, removal of supernatant and addition of 3 l drinking water; aeration and stirring for 20 minutes; settling and 
removal of supernatant; addition of 200 ml synthetic wastewater, completion to 4 l with  drinking water; stirring and aeration until day of test;  settlingand removal of 3 l supernatant; completion to 3 l with fresh drinking water; adjustment of dry weight contents to 2.99 g/l by removal of 800 ml.

Study design

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

Test conditions

Test temperature:
18.0 - 19.2 °C
pH:
 8.3-8.6
Nominal and measured concentrations:
Nominal concentrations: 220, 440, 880, 1760 and 3520 mg/L
Details on test conditions:
TEST SYSTEM
- Preparation of test solutions: 100 ml drinking water + calculated amount of test substance; addition of a mixture of 200 ml inoculum, 16 ml 
synthetic wastewater, 184 ml drinking water. Solutions were prepared and tested at 10 min intervals, the first and  the last being the untreated controls.
- Concentrations: Activated sludge: 1.194 g dry weight/l; Test substance: 220; 440; 880; 1760; 3520 mg/l
- Renewal of test solution: no
- Exposure vessel type: troug filled with 500 ml test solution; continuous stirring and aeration.
- Number of replicates: 1
- Controls (No. of replicates): Untreated (2 replicates)

TEST PARAMETER: oxygen consumption of a well mixed aliquot measured for  6.5 - 9 minutes and recorded at 30 sec intervals

STATISTICAL METHODS: linear regression after conversion to probit(inhibition) and logarithm (concentration).
Reference substance (positive control):
yes
Remarks:
3,5-dichlorophenol

Results and discussion

Effect concentrationsopen allclose all
Duration:
3 h
Dose descriptor:
EC10
Effect conc.:
598 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
1 745 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Results with reference substance (positive control):
3,5-dichlorophenol: 5; 15; 30 mg/l (1 replicate)
Results: 5 mg/l: 44.1 % ; 15 mg/l: 65.3 % ; 30 mg/l: 81.5 %   
EC50 = 6.78 mg/l

Any other information on results incl. tables

- Oxygen consumption of controls:
  Control 1: 29.48 mg O2/(l * h)
  Control 2: 30.30 mg O2/(l * h)
  Difference: 2.7 %
- Effect data: Percent inhibition (relative to arithmetic mean oxygen consumption of controls)
   220 mg/l: -2.7 %
   440 mg/l:  5.0 %
   880 mg/l: 16.6 %
  1760 mg/l: 50.3 %
  3520 mg/l: 81.2 %

   

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The EC50 (3 hours) was determined as 1745 mg/L indicating that the test substance does not pose a significant hazard to microorganisms populating sewage sludge.
Executive summary:

The inhibitory effects of 1,5 -cyclooctadiene on the respiration rate of activated sludge were determined over a contact time of 3 hours according to EU method C.11 (Hüls AG, 1998). The inhibitory effect of the test substanceat a particular concentration was expressed as a percentage of the mean respiration rates of twocontrols. The following EC50 value was calculated from determinations at 5 different concentrations ranging from 220 to 3520 mg/L:

EC50 (3 hours): 1745 mg/L

The study was assessed as "reliable without restrictions".