α,α,α-trifluoro-m-cresol

Toxicity to microorganisms

Link to relevant study record(s)

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:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

- Principle of test: bacterial growth inhibition assay performed on E.coli.
- Short description of test conditions: minimal inhibitory concentration (MIC) values were determined according to standard procedures (Krüger-Thiemer et al., 1965). The bacterial strains used were E. coli ATCC 11775 and, for MIC determination, also Mycobacterium smegmatis M169. Along with the Coulter counter experiments, samples were drawn from the cultures under toxicant treatment, diluted to 10-100 organisms/ml, allowed to multiply for 48h at 37ºC, and the colonies were counted. IC50 was determined.
- Parameters analysed / observed: viable counts, Laser Microprobe Mass Analysis (LAMMA) investigations of their effects on the intracellular Na+/K+ ratio of E. coli..

GLP compliance:

no

Specific details on test material used for the study:

The test chemicals were purchased from Merck or Aldrich at the highest grade of purity available.

Analytical monitoring:

not specified

Details on sampling:

- Sampling method: Every 45 min samples were taken and the number of organisms per milliliter was counted.

Vehicle:

no

Test organisms (species):

Escherichia coli

Details on inoculum:

- Laboratory culture: E. coli ATCC 11775
- Source: purchased from the American Type Culture Collection
- Method of cultivation: Stock cultures were maintained on agar slants at room temperature. The culture broth was dextrose-salts-casamino acids (vitamin-free), pH 6.9. The medium was sterilized by filtration through cellulose ester membranes (0.22 u).
- Preparation of inoculum for exposure: A broth culture was inoculated from an agar culture and the bacteria allowed to grow for 12 to 16 hr at 37°C. From this broth, cultures were prepared by dilution with medium to obtain lo4 cells/ml. Portions of 150 ml were transfered to 1-liter Erlenmeyer flasks. Thirty minutes later when the bacteria were in the logarithmic growth phase the chemical was added.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Details on test conditions:

TEST SYSTEM
- Test vessel: 1L Erlenmeyer flasks.
- Material, size, headspace, fill volume: glass, 1L, fill volume 150 mL.
- Nutrients provided for bacteria:
- Nitrification inhibitor used (delete if not applicable): none / N-allylthiourea
- Biomass loading rate:
TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:
- Particulate matter:
OTHER TEST CONDITIONS
- Adjustment of pH:
- Photoperiod:
- Light intensity:
- Details on termination of incubation:
EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
TEST CONCENTRATIONS
- Spacing factor for test concentrations:
- Justification for using fewer concentrations than requested by guideline:
- Range finding study
- Test concentrations:
- Results used to determine the conditions for the definitive study:

Key result

Duration:

12 h

Dose descriptor:

IC50

Effect conc.:

56.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Key result

Duration:

12 h

Dose descriptor:

IC50

Effect conc.:

0.35 mmol/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Duration:

12 h

Dose descriptor:

other: MIC

Effect conc.:

1 mmol/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Details on results:

- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values:
- Effect concentrations exceeding solubility of substance in test medium:
- Adsorption (e.g. of test material to the walls of the test container):
- Blank controls oxygen uptake rate:
- Coefficient of variation of oxygen uptake rate in control replicates:

Validity criteria fulfilled:

not specified

Conclusions:

Under test conditions, the IC50 of the test item in E.coli was determined to be 56.2 mg/L.

Executive summary:

A bacterial growth inhibition study / bacterial growth kinetics study was performed with the test item on Escherichia coli, in order to assess its potential toxicity. Bacterial cultures were exposed to Minimal inhibitory concentration (MIC) values were determined according to standard procedures in E. coli ATCC 11775 and Mycobacterium smegmatis M169. Along with the Coulter counter experiments, samples were drawn from the cultures under toxicant treatment, diluted to 10-100 organisms/ml, allowed to multiply for 48h at 37ºC, and the colonies were counted. IC50 was determined. Under test conditions, the IC50 of the test item in E.coli was determined to be 56.2 mg/L.

Description of key information

Key study. Bacterial growth inhibition study (no TG). The EC50 of the test item in Escherichia coli was determined to be 56.2 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:

56.2 mg/L

Additional information

A bacterial growth inhibition study / bacterial growth kinetics study was performed with the test item onEscherichia coli, in order to assess its potential toxicity. Bacterial cultures were exposed to Minimal inhibitory concentration (MIC) values were determined according to standard procedures in E. coli ATCC 11775 and Mycobacterium smegmatis M169. Along with the Coulter counter experiments, samples were drawn from the cultures under toxicant treatment, diluted to 10-100 organisms/ml, allowed to multiply for 48h at 37ºC, and the colonies were counted. IC50 was determined. Under test conditions, the IC50 of the test item in E.coli was determined to be 56.2 mg/L.