2,5-xylenol

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to microorganisms, other

Remarks:

Tetrahymena pyriformis

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:

Test procedure according to T.W. Schultz (1993) Aquatic toxicology of nitrogen heterocyclic molecules: Quantitative structure-activity relationship, in J.O. Nriagu, (Ed.) Aquatic Toxicology, Wiley, New York, 1983, 579-612.

GLP compliance:

no

Specific details on test material used for the study:

purchased from commercial sources (Aldrich Chemical Co., Milwaukee, WI, U.S.A. or Pfaltz and Bauer Inc., Sanford, CT, U.S.A.) and not repurified.

Analytical monitoring:

no

Vehicle:

yes

Remarks:

dimethylsulfoxide (DMSO)

Details on test solutions:

Due to solubility and toxicity differences, stock solutions of the individual test compounds were prepared in dimethylsulfoxide (DMSO) at a number of concentrations: 5000,
10000, 25000, or 50000 mg/L. In all cases the amount of stock solution added to the cultures was less than 0.75%. Such levels have no effect on Tetrahymena growth.

Test organisms (species):

Tetrahymena pyriformis

Details on inoculum:

Axenic cultures used.

Test type:

not specified

Water media type:

freshwater

Limit test:

no

Total exposure duration:

60 h

Nominal and measured concentrations:

5 concentrations tested and a control

Details on test conditions:

- Cell-population levels were estimated spectrophotometrically
- Assayed in duplicate for a minimum of 3 replicates.

Reference substance (positive control):

not specified

Duration:

60 h

Dose descriptor:

IC50

Effect conc.:

119.62 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Remarks on result:

other: 95% CL: 99.57 - 155.38 mg/L

Reported statistics and error estimates:

Biological response was determined using probit analysis in the Statistical Analysis System software. In this analysis, Y equaled the % control absorbance and X equaled the concentration of toxicant in mg/L.

Validity criteria fulfilled:

not applicable

Description of key information

IC50 (60 h): 119.62 mg/L (nominal)

Key value for chemical safety assessment

EC50 for microorganisms:

119.62 mg/L

Additional information

The toxicity of 2,5-Xylenol to aquatic microorganisms was investigated in a study on the ciliate Tetrahymena pyriformis. The ciliates were exposed to five different concentrations for a test period of 60 hours. Cell-population levels were estimated spectrophotometrically. The determined IC50 (60 h) was 119.62 mg/L (nominal) based on growth inhibition.