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Toxicity to microorganisms

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Reference
Endpoint:
toxicity to microorganisms, other
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Justification for type of information:
Data is from peer reviewed journal
Qualifier:
according to guideline
Guideline:
other: Refer below principle
Principles of method if other than guideline:
Toxicity of the test chemical was determined on the basis of bioluminescence response of the marine bacteria Vibrio fischeri.
GLP compliance:
not specified
Analytical monitoring:
not specified
Vehicle:
not specified
Test organisms (species):
Vibrio fisheri
Test type:
not specified
Water media type:
other: marine
Total exposure duration:
30 min
Test temperature:
15°C
pH:
7
Details on test conditions:
EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : After 5, 15, and 30 minutes of exposure to the compound, the light output of the luminescent bacteria was measured and
compared with the light output of a blank control.


Reference substance (positive control):
not specified
Key result
Duration:
5 min
Dose descriptor:
EC50
Effect conc.:
15.6 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Remarks on result:
other: 95% C. I. = 14.8 to 16.5 mg/l
Key result
Duration:
15 min
Dose descriptor:
EC50
Effect conc.:
15.4 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Remarks on result:
other: 95% C. I. = 14.3 to 16.4 mg/l
Key result
Duration:
30 min
Dose descriptor:
EC50
Effect conc.:
14.9 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Remarks on result:
other: 95% C. I. = 14.2 to 15.6 mg/l
Reported statistics and error estimates:
The toxicity was evaluated, a 50% reduction in luminescence, corresponding to the EC50, and the respective 95% confidence intervals were computed using the Microtox Omni™ Software version 4.3.0.1. Additional statistical analysis, namely the respective 95% confidence intervals, which were estimated for each compound by non-linear regression, using the least squares method to fit the data to the logistic equation, was performed by the STATISTICA software, version 8.0.
Validity criteria fulfilled:
not specified
Conclusions:
Based on the inhibition bioluminescence response of the marine bacteria Vibrio fischeri, median effective concentration (EC50) value after 5, 15 and 30 min was determined to be 15.6 mg/l (95% C. I. = 14.8 to 16.5 mg/l), 15.4 mg/l (95% C. I. = 14.3 to 16.4 mg/l) and 14.9 mg/l (95% C. I. = 14.2 to 15.6 mg/l), respectively.
Executive summary:

Toxicity to marine bacteria Vibrio fischeri study was carried out for 30 mins. The standard Microtox toxicity test liquid-phase assay was used to evaluate the inhibition of the marine bacteria Vibrio fischeri bioluminescence at 15 °C and pH 7.0. The test was performed by measuring the bacteria luminescence variation when exposed to test chemical concentrations, with successive dilutions by a factor of 2 (from 0.32 to 81.9%), in which 100% of the compound corresponds to a known concentration (this concentration varies with the compound tested) of a stock solution, in which 0% corresponds to the control. After 5, 15, and 30 minutes of exposure to the compound, the light output of the luminescent bacteria was measured and compared with the light output of a blank control. The toxicity was evaluated, a 50% reduction in luminescence, corresponding to the EC50, and the respective 95% confidence intervals were computed using the Microtox Omni™ Software version 4.3.0.1. Additional statistical analysis, namely the respective 95% confidence intervals, which were estimated for each compound by non-linear regression, using the least squares method to fit the data to the logistic equation, was performed by the STATISTICA software, version 8.0. On the basis of the inhibition bioluminescence response of the marine bacteria Vibrio fischeri, median effective concentration (EC50) value after 5, 15 and 30 min was determined to be 15.6 mg/l (95% C. I. = 14.8 to 16.5 mg/l), 15.4 mg/l (95% C. I. = 14.3 to 16.4 mg/l) and 14.9 mg/l (95% C. I. = 14.2 to 15.6 mg/l), respectively.

Description of key information

Toxicity to marine bacteria Vibrio fischeri study was carried out for 30 mins (Sónia P. M. Ventura et. al., 2016). The standard Microtox toxicity test liquid-phase assay was used to evaluate the inhibition of the marine bacteria Vibrio fischeri bioluminescence at 15 °C and pH 7.0. The test was performed by measuring the bacteria luminescence variation when exposed to test chemical concentrations, with successive dilutions by a factor of 2 (from 0.32 to 81.9%), in which 100% of the compound corresponds to a known concentration (this concentration varies with the compound tested) of a stock solution, in which 0% corresponds to the control. After 5, 15, and 30 minutes of exposure to the compound, the light output of the luminescent bacteria was measured and compared with the light output of a blank control. The toxicity was evaluated, a 50% reduction in luminescence, corresponding to the EC50, and the respective 95% confidence intervals were computed using the Microtox Omni™ Software version 4.3.0.1. Additional statistical analysis, namely the respective 95% confidence intervals, which were estimated for each compound by non-linear regression, using the least squares method to fit the data to the logistic equation, was performed by the STATISTICA software, version 8.0. On the basis of the inhibition bioluminescence response of the marine bacteria Vibrio fischeri, median effective concentration (EC50) value after 5, 15 and 30 min was determined to be 15.6 mg/l (95% C. I. = 14.8 to 16.5 mg/l), 15.4 mg/l (95% C. I. = 14.3 to 16.4 mg/l) and 14.9 mg/l (95% C. I. = 14.2 to 15.6 mg/l), respectively.

Key value for chemical safety assessment

EC50 for microorganisms:
14.9 mg/L

Additional information

Experimental study of the test chemical and various supporting weight of evidence studies for its read across chemical were reviewed for toxicity to micro-organisms end point which are summarized as below:

 

In an experimental study from peer reviewed journal (Sónia P. M. Ventura et. al., 2016), toxicity toxicity to marine bacteria Vibrio fischeri study was carried out for 30 mins. The standard Microtox toxicity test liquid-phase assay was used to evaluate the inhibition of the marine bacteria Vibrio fischeri bioluminescence at 15 °C and pH 7.0. The test was performed by measuring the bacteria luminescence variation when exposed to test chemical concentrations, with successive dilutions by a factor of 2 (from 0.32 to 81.9%), in which 100% of the compound corresponds to a known concentration (this concentration varies with the compound tested) of a stock solution, in which 0% corresponds to the control. After 5, 15, and 30 minutes of exposure to the compound, the light output of the luminescent bacteria was measured and compared with the light output of a blank control. The toxicity was evaluated, a 50% reduction in luminescence, corresponding to the EC50, and the respective 95% confidence intervals were computed using the Microtox Omni™ Software version 4.3.0.1. Additional statistical analysis, namely the respective 95% confidence intervals, which were estimated for each compound by non-linear regression, using the least squares method to fit the data to the logistic equation, was performed by the STATISTICA software, version 8.0. On the basis of the inhibition bioluminescence response of the marine bacteria Vibrio fischeri, median effective concentration (EC50) value after 5, 15 and 30 min was determined to be 15.6 mg/l (95% C. I. = 14.8 to 16.5 mg/l), 15.4 mg/l (95% C. I. = 14.3 to 16.4 mg/l) and 14.9 mg/l (95% C. I. = 14.2 to 15.6 mg/l), respectively.

 

In a supporting weight of evidence study, toxicity to Pseudomonas putida study (from peer reviewed journal (1980), handbook and secondary source) was carried out for 16 hr. The study was based on the effects of the test chemical on Pseudomonas putida at a temperature of 25°C. Test chemical of known concentration was prepared in sterile double distilled water. Composition of test medium contains sodium nitrate (1.06 g), dipotassium hydrogen phosphate (0.6 g), magnesium sulphate (0.2 g), D (+) glucose (10 g), Difco bacto agar (18 g), ferrous sulphate (0.001 g), and 1.5 ml trace element solution. Pseudomonas putida was used as a test organism. Keep stock cultures of the test strain, Pseudomonas putida, on the nutrient for stock and preliminary cultures in agar slant tubes. Prepare, for onward culturing of the test strain, new stock cultures at intervals of 1 week each. Incubate the inoculated stock cultures at 25"C for 24 h and keep in stock. stock. If needed, prepare preliminary cultures from stock cultures on the above mentioned nutrient medium in agar slant tubes and incubate at 25°C for 24 h. Then, wash off the cell material with sterile saline. Determine the extinction of the monochromatic radiation at 436nm for a 10 mm layer of the bacterial suspension by photoelectric measurement. Erlenmeyer flask of 300 ml stoppered with cottoned lined plastic caps was used for the study. Prepare dilution series in the test vessel. Each of the dilutions contains 1 part v/v of the pollutant solution in 20 to 214 parts v/v of mixture. Prepare the dilution series as follows: the first flask of each series contains 160ml of pollutant solution at the start. Starting from this flask prepare the subsequent dilution stein at a constant dilution ratio by consistently mixing 80ml of preliminary pollutant dilution and 80 ml double distilled water. Consequently, each flask contains 80 ml of culture liquid at the start. Make up each flask of the three dilution series to beinoculatedto 100 ml by adding 5 ml each of stock solution I, 5 ml each of stock solution II and I0 ml each of the prepared bacterial suspension from the preliminary culture having a known adjusted extinction value. Leave both inoculated and non-inoculated dilution series at 25°C for 16 h. After termination of the test period measure the extinction of the monochromatic radiation at 436 nm in a 10-mm layer in the inoculated dilution series. On the basis of the effect of test chemical on growth rate, i.e., multiplication of the test organism Pseudomonas putida, the 16 h EC0 and EC50 value was determined to be 16 and > 16 mg/l.

 

For the test chemical from peer reviewed journal, toxicity to marine bacteria Vibrio fischeri study was carried out for 30 mins. The standard Microtox toxicity test liquid-phase assay was used to evaluate the inhibition of the marine bacteria Vibrio fischeri bioluminescence at 15 °C and pH 7.0. The test was performed by measuring the bacteria luminescence variation when exposed to test chemical concentrations, with successive dilutions by a factor of 2 (from 0.32 to 81.9%), in which 100% of the compound corresponds to a known concentration (this concentration varies with the compound tested) of a stock solution, in which 0% corresponds to the control. After 5, 15, and 30 minutes of exposure to the compound, the light output of the luminescent bacteria was measured and compared with the light output of a blank control. The toxicity was evaluated, a 50% reduction in luminescence, corresponding to the EC50, and the respective 95% confidence intervals were computed using the Microtox Omni™ Software version 4.3.0.1. Additional statistical analysis, namely the respective 95% confidence intervals, which were estimated for each compound by non-linear regression, using the least squares method to fit the data to the logistic equation, was performed by the STATISTICA software, version 8.0. On the basis of the inhibition bioluminescence response of the marine bacteria Vibrio fischeri, median effective concentration (EC50) value after 5, 15 and 30 min was determined to be 10.4 mg/l (95% C. I. = 9.3 to 11.5 mg/l), 9.66 mg/l (95% C. I. = 8.53 to 10.8 mg/l) and 9.57 mg/l (95% C. I. = 8.31 to 10.8 mg/l), respectively.

 

On the basis of the experimental studies, the EC50 value of the test chemical on test organism was determined to be ranges from 9.57 to > 16mg/l, respectively.