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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:
1990-08-2 to 1990-09-03
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: According OECD 209, non GLP, limited information on test substance
Qualifier:
according to guideline
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Deviations:
yes
Remarks:
Instead of using 3,5-dichlorophenol as reference (acc. to OECD 209) potassium dichromate was used in a concentration to inhibit respiration of 50%.
Principles of method if other than guideline:
Instead of using 3,5-dichlorophenol as reference (acc. to OECD 209) potassium dichromate was used in a concentration to inhibit respiration of 50%.
GLP compliance:
no
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
no furhter details are available
Analytical monitoring:
no
Details on sampling:
not applicable as nominal test concentrations are evaluated
Vehicle:
no
Details on test solutions:
no further details available
Test organisms (species):
activated sludge, domestic
Details on inoculum:
- Laboratory culture: activated sludge from municipal waste water treatment plant Hildesheim
- Method of cultivation:
- Preparation of inoculum for exposure: washed twice with dechlorinated, autoclaved tap water
- Pretreatment: none
- Initial biomass concentration: 1.251 g/L dry weight
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h
Post exposure observation period:
not applicable
Hardness:
not specified
Test temperature:
22°C
pH:
not specified
Dissolved oxygen:
not specified
Salinity:
not specified
Nominal and measured concentrations:
nominal: 10 - 18 - 32 - 58 - 100 - 180 mg/L
Details on test conditions:
TEST SYSTEM
TEST SYSTEM
- Test vessel:500 mL Erlenmeyer flasks
- Type (delete if not applicable): not specified
- Material, size, headspace, fill volume: 500mL
- Aeration: yes, permanently
- Type of flow-through (e.g. peristaltic or proportional diluter): not specified
- Renewal rate of test solution (frequency/flow rate):not specified
- No. of organisms per vessel:not specified
- No. of vessels per concentration (replicates):1
- No. of vessels per control (replicates):1


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: synthetic water acc. to OECD 209

OTHER TEST CONDITIONS
- Adjustment of pH: not specified
- Photoperiod: not specified
- Light intensity: not specified



Reference substance (positive control):
yes
Remarks:
kaliumdichromat
Key result
Duration:
3 h
Dose descriptor:
EC10
Effect conc.:
9.5 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Remarks on result:
other: n.a.
Duration:
3 h
Dose descriptor:
other: EC20
Effect conc.:
16 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Remarks on result:
other: n.a.
Key result
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
43 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Remarks on result:
other: n.a.
Duration:
3 h
Dose descriptor:
other: EC80
Effect conc.:
120 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Remarks on result:
other: n.a.
Details on results:
no further details available
Results with reference substance (positive control):
- Results with reference substance valid? yes
- Relevant effect levels: 32 - 58 - 100 mg/ L
Reported statistics and error estimates:
no further details available

no further details available

Validity criteria fulfilled:
yes
Conclusions:
Test results are plausible and valid:
EC 10-Wert: 9.5 mg/L
EC 20-Wert: 16 mg/L
EC 50-Wert: 43 mg/L
EC 80-Wert: 120 mg/L

P 95 %: 11.26 < 43 < 164.17
Executive summary:

Test results are plausible and valid. Level of detail in the report reflect testing strategy and reporting of 1990.

Description of key information

Test results are plausible and valid:
EC 10-Wert: 9.5 mg/L
EC 20-Wert: 16 mg/L
EC 50-Wert: 43 mg/L
EC 80-Wert: 120 mg/L
P 95 %: 11.26 < 43 < 164.17

Key value for chemical safety assessment

EC50 for microorganisms:
43 mg/L
EC10 or NOEC for microorganisms:
9.5 mg/L

Additional information