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Ecotoxicological information

Toxicity to microorganisms

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Reference
Endpoint:
toxicity to microorganisms, other
Remarks:
growth inhibition effect on activated sludge microorganisms
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with national standard methods with acceptable restrictions
Justification for type of information:
Data is from peer reviewed journal
Qualifier:
according to
Guideline:
other: as mentioned below
Principles of method if other than guideline:
The growth inhibition effect of the test substance 4-(phenylazo)benzene-1,3-diamine on activated sludge microorganisms was studied.
GLP compliance:
not specified
Analytical monitoring:
not specified
Vehicle:
yes
Remarks:
2 % aqueous ethanol solution
Details on test solutions:
Test concentration: 0.17 m.mole/L (maximum experimental concentration)
Test organisms (species):
activated sludge
Details on inoculum:
The mixed microorganisms were obtained from supernatant of activated sludge and pre-incubated with the medium without azo compounds for 2 days. The microorganisms were inoculated to the experimental medium to give the optical density of the culture at 0.02-0.05. Incubation temperature was at 25±1 deg. C
Test type:
static
Water media type:
freshwater
Remarks on exposure duration:
Not specified
Post exposure observation period:
Not specified
Hardness:
Not specified
Test temperature:
25±1 deg. C
pH:
Not specified
Dissolved oxygen:
Not specified
Salinity:
Not specified
Conductivity:
Not specified
Nominal and measured concentrations:
Test concentration: 0.17 m.mole/L (maximum experimental concentration)
Details on test conditions:
Culture Medium is as follows:
Glucose: 500 ppm
Peptone: 500 ppm
KH2PO4:0 270 ppm
K2HPO4: 100 ppm
Na2HPO4: 660 ppm
MgSO4. 7H20: 2 ppm
CaCI2: 0.0200 ppm
FeSO4. 7H20: 0.0200 ppm
in 2 % aqueous ethanol solution
Reference substance (positive control):
not specified
Key result
Dose descriptor:
other: IGC50
Effect conc.:
0.087 mmol/L
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Remarks on result:
other: duration not specified
Details on results:
Not specified
Results with reference substance (positive control):
Not specified
Reported statistics and error estimates:
Not specified

50 % Growth Inhibition Concentrations (Ø) of test substance:

Compound

Medium

log Ø

log C

log Poct

2,4-DIAMINOAZOBENZENE

[4-(phenylazo)benzene-1,3-diamine]

e

-1.056

-0.752

2.19

 

Ø; concentration of 50 % growth inhibition (m.mole/l.)
C; maximum experimental concentration (m.mole/l.)
Poct; partition coefficient between octanol and water
e; 2 % aqueous ethanol solution

Validity criteria fulfilled:
not specified
Conclusions:
50 % growth inhibition concentration (IGC50) of the test substance 4-(phenylazo)benzene-1,3-diamine on mixed culture of microorganisms was observed to be 0.087 m.mole/L. The study concludes that the test substance showed strong growth inhibition effect on the microorganisms.
Executive summary:

In order to evaluate the effect of test substance 4-(phenylazo)benzene-1,3-diamine on the biological waste treatment, the growth inhibition effect of it on activated sludge microorganisms was studied. Growth inhibition effect was evaluated by the concentration of test compound in which logarithmic phase growth rate constant was decreased to 50 % of that of the culture without test compound. Growth rate constant was determined with turbidity of that of the culture at 660 nm. The mixed microorganisms were obtained from supernatant of activated sludge and pre-incubated with the medium without azo compounds for 2 days. The microorganisms were inoculated to the experimental medium to give the optical density of the culture at 0.02-0.05. Incubation temperature was at 25±1 deg C. 50 % growth inhibition concentration (IGC50) of the test substance 4-(phenylazo)benzene-1,3-diamine on mixed culture of microorganisms was observed to be 0.087 m.mole/L. The study concludes that the test substance showed strong growth inhibition effect on the microorganisms.

Description of key information

50 % growth inhibition concentration (IGC50) of the test substance 4-(phenylazo)benzene-1,3-diamine on mixed culture of microorganisms was observed to be 0.087 m.mole/L. The study concludes that the test substance showed strong growth inhibition effect on the microorganisms.

Key value for chemical safety assessment

Additional information

In order to evaluate the effect of test substance 4-(phenylazo)benzene-1,3-diamine on the biological waste treatment, the growth inhibition effect of it on activated sludge microorganisms was studied. Growth inhibition effect was evaluated by the concentration of test compound in which logarithmic phase growth rate constant was decreased to 50 % of that of the culture without test compound. Growth rate constant was determined with turbidity of that of the culture at 660 nm. The mixed microorganisms were obtained from supernatant of activated sludge and pre-incubated with the medium without azo compounds for 2 days. The microorganisms were inoculated to the experimental medium to give the optical density of the culture at 0.02-0.05. Incubation temperature was at 25±1 deg C. 50 % growth inhibition concentration (IGC50) of the test substance 4-(phenylazo)benzene-1,3-diamine on mixed culture of microorganisms was observed to be 0.087 m.mole/L. The study concludes that the test substance showed strong growth inhibition effect on the microorganisms.