2,3,5-trimethylphenol

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to microorganisms, other

Type of information:

experimental study

Adequacy of study:

weight of evidence

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 toxicity of test substance 2,3,5-trimethylphenol was determined with a Microtox model 500 toxicity autoanalyzer (Microbics Corp., Carlsbad, Calif.)

GLP compliance:

not specified

Specific details on test material used for the study:

- Name of test material (as cited in study report): 2,3,5Trimethylphenol
- Molecular formula (if other than submission substance): C9H12O
- Molecular weight (if other than submission substance): 136.193 g/mol
- Smiles notation (if other than submission substance): c1(c(cc(C)cc1O)C)C
- InChl (if other than submission substance): 1S/C9H12O/c1647(2)8(3)9(10)56/h45,10H,13H3
- Substance type: Organic
- Physical state: Solid

Analytical monitoring:

yes

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method:Each flask containing 25 ml of GWM was inoculated with 1.0 ml (27 pLg of bacterial protein) of the soil microbial suspension.

Test organisms (species):

other: "creosote-adapted" microorganisms

Details on inoculum:

Microbial inoculum was prepared by mixing 25 g of creosote-contaminated surface soil freshly obtained from the American Creosote Works site with 100 ml of 2.5 mM phosphate buffer (pH 7). After being mixed well, the suspension was centrifuged (2,500 rpm, 10 min) to remove larger soil particles. The resultant supernatant was decanted and used as a source of indigenous, "creosote-adapted"microorganisms for the groundwater medium (GWM)

Test type:

static

Water media type:

freshwater

Total exposure duration:

14 d

Hardness:

No data

Test temperature:

30°C

pH:

7

Dissolved oxygen:

No data

Salinity:

No data

Conductivity:

No data

Details on test conditions:

TEST SYSTEM
- Test vessel:125-ml Erlenmeyer flasks fitted with Teflon-lined screw caps
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume:12.5 ml

OTHER TEST CONDITIONS
- Adjustment of pH:adjusted to pH 12.0 with 1 N NaOH

Reference substance (positive control):

not specified

Key result

Duration:

14 d

Dose descriptor:

EC50

Effect conc.:

7 000 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

other: measuring the change in light level of viable luminescent bacteria upon their exposure to test substrates.

Remarks on result:

other: Microtox assays demonstrated a 50% effective concentration (EC50) of 0.72 (a solution containing 0.72% parent material killed 50% of the test organisms) 0.72% cocentration equivalent to 7000 mg/l

Validity criteria fulfilled:

not specified

Conclusions:

Microtox assays demonstrated a 50% effective concentration (EC50) of 0.72 (a solution containing 0.72% parent material killed 50% of the test organisms) this 0.72% concentration equivalent to 7000 mg/l of test substance 2,3,5-trimethylphenol.

Executive summary:

The toxicity of test substance 2,3,5-trimethylphenol was determined with a Microtox model 500 toxicity autoanalyzer (Microbics Corp., Carlsbad, Calif.)

Microbial inoculum was prepared by mixing 25 g of creosote-contaminated surface soil freshly obtained from the American Creosote Works site with 100 ml of 2.5 mM phosphate buffer (pH 7). After being mixed well, the suspension was centrifuged (2,500 rpm, 10 min) to remove larger soil particles. The resultant supernatant was decanted and used as a source of indigenous, "creosote-adapted"microorganisms for the groundwater medium (GWM).Each flask containing 25 ml of GWM was inoculated with 1.0 ml (27 pLg of bacterial protein) of the soil microbial suspension.

The Microtox assays demonstrated a 50% effective concentration (EC50) of 0.72 (a solution containing 0.72% parent material killed 50% of the test organisms) this 0.72% concentration equivalent to 7000 mg/l of test substance 2,3,5-trimethylphenol.

Description of key information

The toxicity of test substance 2,3,5-trimethylphenol was determined with a Microtox model 500 toxicity autoanalyzer (Microbics Corp., Carlsbad, Calif.)

Microbial inoculum was prepared by mixing 25 g of creosote-contaminated surface soil freshly obtained from the American Creosote Works site with 100 ml of 2.5 mM phosphate buffer (pH 7). After being mixed well, the suspension was centrifuged (2,500 rpm, 10 min) to remove larger soil particles. The resultant supernatant was decanted and used as a source of indigenous, "creosote-adapted"microorganisms for the groundwater medium (GWM).Each flask containing 25 ml of GWM was inoculated with 1.0 ml (27 pLg of bacterial protein) of the soil microbial suspension.

The Microtox assays demonstrated a 50% effective concentration (EC50) of 0.72 (a solution containing 0.72% parent material killed 50% of the test organisms) this 0.72% concentration equivalent to 7000 mg/l of test substance 2,3,5-trimethylphenol.

Key value for chemical safety assessment

EC50 for microorganisms:

7 000 mg/L

Additional information

Three studies including experimental data from peer reviewed journals for toxicity to micro organism endpoint of test chemical 2, 3, 5-trimethylphenol (Cas no. 697-82-5) with relevant read across which is structurally similar to target were summarized as followed:

First experimental study (APPLIED AND ENVIRONMENTAL MICROBIOLOGY, May 1991, p. 1277-1285)suggest the toxicity of test substance 2,3,5-trimethylphenol was determined with a Microtox model 500 toxicity autoanalyzer (Microbics Corp., Carlsbad, Calif.) Microbial inoculum was prepared by mixing 25 g of creosote-contaminated surface soil freshly obtained from the American Creosote Works site with 100 ml of 2.5 mM phosphate buffer (pH 7). After being mixed well, the suspension was centrifuged (2,500 rpm, 10 min) to remove larger soil particles. The resultant supernatant was decanted and used as a source of indigenous, "creosote-adapted"microorganisms for the groundwater medium (GWM).Each flask containing 25 ml of GWM was inoculated with 1.0 ml (27 pLg of bacterial protein) of the soil microbial suspension. The Microtox assays demonstrated a 50% effective concentration (EC50) of 0.72 (a solution containing 0.72% parent material killed 50% of the test organisms) this 0.72% concentration equivalent to 7000 mg/l of test substance 2,3,5-trimethylphenol.

And one another peer reviewed journal Chemical Research in Toxicology; vol. 12; nb. 12; (1999); p. 1262 – 1267 for target chemical indicate Population growth impairment testing with the ciliate T. pyriformis (strain GL-C) was conducted following the protocol described by Schultz of test substance 2,3,5-trimethylphenol.

The test protocol allows for eight to nine cell cycles in controls. Following range finding, each chemical was tested in three replicate tests (or assays). Two controls were used to provide a measure of the acceptability of the test by indicating the suitability of the medium and test conditions as well as a basis for interpreting data from other treatments. The first control had no test material and was inoculated with T. pyriformis. The other, a blank, had neither test material nor ciliates. Test replicate consisted of six to eight different concentrations.The IGC50 is calculated by Structure-toxicity models using the regression procedure of MINITAB version 12.1.

A test on growth impairment with Tetrahymena pyriformis results in an inhibitory growth concentration (IGC50) of 1/log IGC50=0.36 which is equivalent to 599.48 (dimensionless) after 40 hours.

Whereas read across chemical 2,3,6 Trimethylphenol (CAS no. 2416-94-6) suggest Inhibition concentration to 50% of test organisms (IGC50) for the substance 2,3,6Trimethylphenol (CAS no. 2416-94-6) was determine to be 52.05 mgl/L on micro organism species Tetrahymena pyriformis (Ciliate) on the basis of effect on Population growth rate in static fresh water.( ECOTOX DATABASE; 2017)

On the basis of available effects values on micro organism from above three studies give the common conclusion as test chemical 2, 3, 5-trimethylphenol (Cas no. 697-82-5) have no concern to micro organism for toxicity in acute exposure period.