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Toxicity to microorganisms

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Reference
Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1996-08-30
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
according to guideline
Guideline:
other: EG-Richtlinie L 133/118 vom 30.5.1988
GLP compliance:
yes
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The test substance was directly given into the test vessels in five different concentrations, the test vessels were 3 h incubated and stirred under permanent ventilation with clean, oil-free air in a water-filled pan
Controls: two replicates blank control, reference control (3,5-Dichlorophenol) in three different concentrations
- Evidence of undissolved material (e.g. precipitate, surface film, etc): no data
Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
- Method of cultivation: not applicable
- Preparation of inoculum for exposure: approximately 5 l activated sludge of the sewage "Marl-Ost" was one-time sedimentated, three-times centrifuged each for 5 minutes 2000 min-1 and washed with 500 - 600 mL drinking water. The activated sludge was taken into 3.5 L drinking water and had a concentration of 3.603 g TS/L, that means for 500 mL test and 200 mL inoculum 1.44 g TS/L..
Test type:
flow-through
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h
Post exposure observation period:
none
Hardness:
no data
Test temperature:
18 - 22 °C
pH:
7.6-7.8
Dissolved oxygen:
>= 2,5 mg/L
Nominal and measured concentrations:
57.4; 92.8; 189.4; 290.8; 380 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: flasks
- Material, fill volume: glass, 500 ml fill volume
- Aeration: continuous
- Renewal rate of test solution (frequency/flow rate): not applicable
- No. of organisms per vessel: not applicable
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 2
- No. of vessels per vehicle control (replicates): not applicable
- Biomass loading rate: 200 mL inoculum; 1.44 g dry weight/L

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Oxygen consumption, pH

Reference substance (positive control):
yes
Remarks:
3,5-Dichlorophenol
Key result
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
> 370 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):
- Results with reference substance valid: yes
- Relevant effect levels: EC50 = 5.1 mg/L
Validity criteria fulfilled:
yes
Executive summary:

Marlowet 4753 (Coconut oil, reaction products with polyethylene glycol and trimethylolpropane) was tested in Activated Sludge Respiration Inhibition Test according to EC guideline 88/302/EC. Within the tested concentration of 57.4; 92.8; 189.4; 290.8 and 380 mg/L there was no significant toxic effect. The determined positive effects were not proportional to increasing concentration. The EC50 was > 370 mg/L rounded up to two significant places. The test substance contents 98.4 % active substance.

Description of key information

Marlowet 4753 (Coconut oil, reaction products with polyethylene glycol and trimethylolpropane) was tested in Activated Sludge Respiration Inhibition Test according to EC guideline 88/302/EC. Within the tested concentration of 57.4; 92.8; 189.4; 290.8 and 380 mg/L there was no significant toxic effect. The determined positive effects were not proportional to increasing concentration. The EC50 was > 370 mg/L rounded up to two significant places. The test substance contents 98.4 % active substance.

Key value for chemical safety assessment

EC50 for microorganisms:
370 mg/L

Additional information