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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:
1997-06-04 till 1997-06-06
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP guideline study with acceptable restrictions.
Qualifier:
according to
Guideline:
other: Official Journal of the European Communities L 133 Part C (Biodegradability: Examination of respiratory inhibition)
Deviations:
no
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
no
Details on sampling:
- Concentrations: 1000, 1800, 3200, 5600 and 10000 mg/L
Vehicle:
no
Details on test solutions:
Direct weighings were prepared to give the different 14H-benz[4,5]isoquino[2,1-a]perimidin-14-one concentrations.
Test organisms (species):
other: activated sludge (mixed population of different microorganisms)
Details on inoculum:
Source: laboratory system predominantly with urban waste water is operated (southern Wupperverband)
Preparation: none
pH of the culture solvent before start of the test: 7.2
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
30 min
Test temperature:
19.8 - 20.3 °C (including all test concentrations, control and reference substance)
pH:
6.9 - 7.1 (including all test concentrations, control and reference substance)
Dissolved oxygen:
5.0 - 5.4 mgO2/L at the start of the test (including all test concentrations, control and reference substance)
2.8 - 3.3 mgO2/L at the end of the test (including all test concentrations, control and reference substance)
8.1 mg /L O2-respiration
Nominal and measured concentrations:
- Concentrations: 1000, 1800, 3200, 5600 and 10000 mg/L
- Concentration of activated sludge: 400 mg/L (because of the strong oxygen consumption of the activated sludge used, only a concentration of 0.4 g/L was used in all approaches.)
- Concentration in the control: 10000 mg/L
Reference substance (positive control):
yes
Remarks:
3,5-dichlorophenol (purity = 97 %)
Duration:
30 min
Dose descriptor:
EC50
Effect conc.:
> 10 000 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):
Reference substance (3,5-Dichorophenol)
Concentrations: 2.5, 5, 10, 20 and 40 mg/L
EC50 = 8.8 mg/L

Results:

Concentration   Respiration rate Test item  Respiration rate abiotic O2 Inhibition 
 (mg/L) (mg/L*h)  (mg/L*h)  (%)
1000   21.0  21.0 10.6 
 1800  20.0  20.0  14.9
 3200  19.5  19.5  17.0
 5600  18.0  18.0  23.4
 10000  18.0  18.0  23.4
 control mean  23.5    
 control 1  24.0    
 control 2  23.0    

The abiotic O2 -consumption was determined at a concentration of 10000 mg/L.

Since no abiotic O2-consumption was obtained no consumption at lower concentrations is expected.

Validity criteria fulfilled:
yes
Remarks:
(-Respiratory rates of the 2 controls differ less than 15 % from each other. - The EC50 of the reference compound 3,5- dochlorophenol is in the range 5 - 30 mg/L.)
Conclusions:
The respiration rate with activated sludge of14H-benz[4,5]isoquino[2,1-a]perimidin-14-one was determined an an EC50 of >10000 mg/L after 30 min.
Executive summary:

In order to test the toxicity to microorganism (activated sludge, mixed population of different microorganisms ) of 14H-benz[4,5]isoquino[2,1-a]perimidin-14-one was determined according to the EU-Method L 133 Part C "Biodegradability: Examination of respiratory inhibition" (equivalent to OECD Guideline No. 209, "Activated sludge, Respiration Inhibition Test). Five concentrations (1000, 1800, 3200, 5600 and 10000 mg/L), control and a positive reference substance (3,5-dichlorophenol) were exposed for a period of 30 min. An EC50 of > 10000 mg/L was obtained on 14H-benz[4,5]isoquino[2,1-a]perimidin-14-one related to respiration rate.

Description of key information

In order to test the toxicity to microorganism (activated sludge, mixed population of different microorganisms ) of 14H-benz[4,5]isoquino[2,1-a]perimidin-14-one was determined according to the EU-Method L 133 Part C "Biodegradability: Examination of respiratory inhibition" (equivalent to OECD Guideline No. 209, "Activated sludge, Respiration Inhibition Test). Five concentrations (1000, 1800, 3200, 5600 and 10000 mg/L), control and a positive reference substance (3,5-dichlorophenol) were exposed for a period of 30 min. An EC50 of > 10000 mg/L was obtained on 14H-benz[4,5]isoquino[2,1-a]perimidin-14-one related to respiration rate.

Key value for chemical safety assessment

EC50 for microorganisms:
10 000 mg/L

Additional information

The key value should read as EC50 >= 10,000 mg/L as there was no effect.