Octan-2-one

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to microorganisms

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Data is from peer reviewed journal

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:

The microorganism test was conducted on Photobacterium phosphoreum to calculate EC50 value of test chemical in microtox test with exposure duration of 5min,15 min and 25 mins.

GLP compliance:

no

Analytical monitoring:

yes

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Chemical name of vehicle (organic solvent, emulsifier or dispersant):NaCL

Test organisms (species):

Photobacterium phosphoreum

Test type:

static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

5 min

Remarks on exposure duration:

test also further conducted for 15 and 25 min.

Hardness:

No data available

Test temperature:

15 deg C

Details on test conditions:

TEST SYSTEM
- No. of vessels per concentration (replicates):triplate was run

Reference substance (positive control):

not specified

Key result

Duration:

5 min

Dose descriptor:

EC50

Effect conc.:

8.91 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Diminshes light emission by 50%

Remarks on result:

other: 69.5±9.2 µM

Key result

Duration:

15 min

Dose descriptor:

EC50

Effect conc.:

9.616 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Diminshes light emission by 50%

Key result

Duration:

25 min

Dose descriptor:

EC50

Effect conc.:

10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Diminshes light emission by 50%

Reported statistics and error estimates:

Student t-test

Validity criteria fulfilled:

not specified

Conclusions:

The EC50 value was found to be 8.910 to 10 mg/L when exposed to Photobacterium phosphoreum with test chemical in microtox test.

Executive summary:

The microtox test was conducted on Photobacterium phosphoreum to determine the EC50 value of chemical exposed with duration of 5 min to 25 min.Analytical analyses done by Gas chromatography/mass spectrometry. and statistical analysis for EC50 determination used Student t-test. During experimental result the EC50 value was found to be 8.910mg/l (69.5±9.2µM), 9.616 mg/L (75±11µM); 10 mg/L (78±11µM) when exposed to Photobacterium phosphoreum with test chemical in microtox test.

Description of key information

Toxicity to microorganism:

The microtox test was conducted on Photobacterium phosphoreum to determine the EC50 value of chemical exposed with duration of 5 min to 15 min.Analytical analyses done by Gas chromatography/mass spectrometry. and statistical analysis for EC50 determination used Student t-test. During experimental result the EC50 value was found to be 8.910 mg/l (69.5±9.2µM), 9.616 mg/L (75±11µM); 10 mg/L (78±11µM) when exposed to Photobacterium phosphoreum with test chemical 2-octanone in microtox test.

Key value for chemical safety assessment

EC50 for microorganisms:

10 mg/L

Additional information

Toxicity to microorganism:

Four studies including experimental studies and modelling database were reviewed for toxicity to microorganisms for test substance , having Klimish rating 2 considering key and supporting, is summarised as followed:

First peer reviewed study suggest The microtox test was conducted on Photobacterium phosphoreum to determine the EC50 value of chemical exposed with duration of 5 min to 25 min.Analytical analyses done by Gas chromatography/mass spectrometry. and statistical analysis for EC50 determination used Student t-test. During experimental result the EC50 value was found to be 8.910mg/l (69.5±9.2µM), 9.616 mg/L (75±11µM); 10 mg/L (78±11µM) when exposed to Photobacterium phosphoreum with test chemical 2-octanone in microtox test.

Another one from SAR and QSAR in Enuironmental Research, journal indicate the toxicity to micro-organisms study was conducted onTetrahymena pyriformisfor 48 hrs. Stock solutions of test chemical was prepared in dimethyl sulfoxide (DMSO) at conc. of 2.5, 5, 10, 25 or 50 mg/l. The volume of stock solution added to each test flask did not exceed 0.35 ml, an amount that does not alter Tetrahymena population growth.Test chemical was tested in a range-finder prior to testing in duplicate for three additional replicates. Each replicate was set up using freshly prepared stock solutions.After 48 hrs of exposure duration of test organism to test chemical 2-octanone,population density was measured spectrophotometrically at 540 nm. The 50 percent growth inhibitory concentration, IGC50, was determined using Probit Analysis of Statistical Analysis System (SAS) software with Yas the absorbency normalized as percentage of control and X as the toxicant concentration in parts per million.Based on growth inhibition of test organism, the IGC50 value was found to be 61.41 mg/l.

And from Microtox study for target from different journal suggest in microtox test which is conducted on Photobacterium phosphoreum to determine the EC50 value of chemical exposed with duration of 5 min. The EC50 value was found to be 17.7 mg/L when exposed to Photobacterium phosphoreum with test chemical in microtox test.

Last study from one another peer reviewed journal Toxicology Methods, indicate toxicity to micro-organisms study was conducted on Tetrahymena pyriformis strain GL for 72 hrs. The assay was conducted in a buffered medium under static conditions.Stock solutions of test chemical was prepared either in solvent DMSO or in distilled water.The solvent DMSO has low toxicity to Tetrahymena,low volatility, and high ability to dissolve organic chemicals. Concentration not greater than 0.75% DMSO (350 µL per 50 mL of medium) are used. This conc. was shown to have no effect on Tetrahymena population growth. Standard stocks are prepared on a milligram per liter basis. When using distilled water for prepare stock solutions, extra care must be taken to maintain sterility. tests were conducted in a 250 mL Erlenmeyer flask containing 50 mL of sterile, semidefined proteose – peptone – based medium and five different conc. of test substance. Then the flasks were inoculated with log-growth-phase culture of Tetrahymena pyriformis of initial cell density of approx. 2500 cells/ml and incubated for about 40 hrs at27 ± 1ᵒC with pH 7.4. After incubation, growth inhibition was measured spectrophotometrically or by electronic particle counting and 50% effect levels are determined at 72 hrs. The nutritional requirement of test organism was met by a solution of proteaose-peptone, yeast extract, glucose, and Fe-EDTA. For test bacterial strain, the optimum temp. for growth was in between 27ᵒC and 35ᵒC and pH range is 5.0 – 8.6, with the optimum pH being 7.5, respectively. Control test vessel contains the test medium inoculated with the test organism with no addition of test chemical and blank was also prepared for the study. The 50% inhibitory growth concentration in mg/l (IGC50) and the 95% fiducial interval are determined for each test compound. The IGC50 was calculated with the probit procedure. Thus, based on growth inhibition of test organism, the IGC50 value was found to be 181.1 and 90.7 mg/l, respectively.

Overall all experimental studies indicate that the EC50 values for 5 min in the range 8.91 mg/l to 17.7 mg/l, for 15 min. -9.616 mg/l and for 25 min-10 mg/l respectively.IGC50 for 72 hrs.was found to be 90.7 mg/l-181.1 mg/l and for 48 hrs it become 61.41 mg/l thus based on the available results it is concluded that test substance may have toxicity concern to micro organisms in acute exposure period.