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Ecotoxicological information

Toxicity to microorganisms

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Reference
Endpoint:
toxicity to microorganisms, other
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Remarks:
Experimental data of various test chemicals
Justification for type of information:
Experimental data of various test chemicals is from collection of data
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Qualifier:
according to
Guideline:
other: Refer below principle
Principles of method if other than guideline:
WoE was prepared for determination of toxicity of test chemical on microorganisms.
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
no
Test organisms (species):
Tetrahymena pyriformis
Details on inoculum:
WoE 2: Tetrahymena pyriformis was preserved in a sterile medium of 2% proteose peptone at 20°C which was renewed at 2-4 week intervals.
Test type:
static
Water media type:
freshwater
Total exposure duration:
24 d
Remarks on exposure duration:
WoE 3: 17 hrs
Test temperature:
2: 30 deg C
Details on test conditions:
2: The stock solution of the chemical was added to the sterile medium to provide a concentration ratio of 1.8 in 10ml of 2% proteose peptone. The solutions were then inoculated with 0.2 ml of pre-cultured T. pyriformis and cultivated at 30°C for 24 h without agitation. The number of cells was then counted.
Reference substance (positive control):
no
Key result
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
32 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Population growth rate
Remarks on result:
other: 2nd study
Duration:
17 h
Dose descriptor:
EC50
Effect conc.:
> 10 000 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Remarks on result:
other: 3rd study
Validity criteria fulfilled:
not specified
Conclusions:
2nd study: The median effective concentration (EC50) value of test chemical in tetrahymena pyriformis was observed to be 32000 mg/L on the basis of population growth rate effect in a 24 hours of exposure.
3rd study: The effect concentration (EC50) value of test chemical on microorganism (Bacteria sp.) in a 17 hrs study was observed at a dose concentration of > 10000 mg/L.
Executive summary:

Based on the effect observation of test chemical on growth of microorganisms, studies have been reviewed and summarized as mention below:

In this study from peer reviewed journal, a test was developed using Tetrahymena pyriformis in order to determine the toxicity of test chemical. Pre-cultured T. pyriformis was exposed for 24 h at 30°C to various concentrations, and the number of T. pyriformis surviving were then counted. The concentration of the chemical, at which the proliferation of T. pyriformis was restricted to one-half of the blank test (EC50), was determined. The median effective concentration (EC50) value of test chemical in tetrahymena pyriformis was observed to be 32000 mg/L on the basis of population growth rate effect in a 24 hours of exposure. Thus, it can be concluded that the test substance does not exhibit any toxicity effect to microorganism (tetrahymena pyriformis).

Similarly in the next study from peer reviewed journal toxicity on the bacterial growth were observed for 17 hrs. Short term toxicity of chemical was studied on the growth of bacteria. The effect concentration (EC50) value of test chemical on microorganism (Bacteria sp.) in a 17 hrs study was observed at a dose concentration of > 10000 mg/L.

Description of key information

2nd study: The median effective concentration (EC50) value of test chemical in tetrahymena pyriformis was observed to be 32000 mg/L on the basis of population growth rate effect in a 24 hours of exposure.

3rd study: The effect concentration (EC50) value of test chemical on microorganism (Bacteria sp.) in a 17 hrs study was observed at a dose concentration of > 10000 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:
32 000 mg/L

Additional information

Based on the effect observation of read across chemical selected on the basis of functional similarity with the test chemical on the growth of microorganisms, studies have been reviewed and summarized as mention below:

 

In this study from peer reviewed journal, a test was developed using Tetrahymena pyriformis in order to determine the toxicity of test chemical. Pre-cultured T. pyriformis was exposed for 24 h at 30°C to various concentrations, and the number of T. pyriformis surviving were then counted. The concentration of the chemical, at which the proliferation of T. pyriformis was restricted to one-half of the blank test (EC50), was determined. The median effective concentration (EC50) value of test chemical in tetrahymena pyriformis was observed to be 32000 mg/L on the basis of population growth rate effect in a 24 hours of exposure. Thus, it can be concluded that the test substance does not exhibit any toxicity effect to microorganism (tetrahymena pyriformis).

 

Similarly in the next study from peer reviewed journal toxicity on the bacterial growth were observed for 17 hrs. Short term toxicity of chemical was studied on the growth of bacteria. The effect concentration (EC50) value of test chemical on microorganism (Bacteria sp.) in a 17 hrs study was observed at a dose concentration of > 10000 mg/L.


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