Registration Dossier

Administrative data

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: Study well documented, meets generally accepted scientific principles.

Data source

Reference
Reference Type:
publication
Title:
Tetratox : Tetrahymena pyriformis population growth impairment endpoint - a surrogate for fish lethality
Author:
Schultz TW
Year:
1997
Bibliographic source:
Toxicol. Methods , 7(4) : 289-309

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Tetratox test
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
no data

Sampling and analysis

Analytical monitoring:
not required

Test solutions

Vehicle:
yes
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: dissolution of the substance in the test medium with vehicle
- Eluate: distilled water
- Controls: Test medium + Inoculum
- Chemical name of vehicle: Solvent dimethyl sulfoxide (DMSO) reagent grade
- Concentration of vehicle in test medium: final test solution concentration :<0.75% (375 µl per 50 ml of medium).

Test organisms

Test organisms (species):
Tetrahymena pyriformis
Details on inoculum:
- Laboratory culture: yes, strain GL-C
- Method of cultivation: growth medium mainly composed with proteose peptone (5g/l), D-glucose (5g/l), yeast extract (1g/l) and Tris-HCl (1.2g/l) in 1000 ml of distilled water. The experiments were conducted with log-growth-phase cultures.
- Preparation of inoculum for exposure: no adaptation, the test medium was the growth medium
- Initial biomass concentration: currently 2500 cells/ml (from 1000 to 5000 cells/ml).

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
40 h

Test conditions

Test temperature:
27+/- 1°C
pH:
7.40 (buffered with Tris-HCl prior sterilization)
Nominal and measured concentrations:
It is supposed that it is based on nominal concentrations.
minimum of 5 concentrations tested, no more details.
Details on test conditions:
Type: aquatic
TEST SYSTEM
- Test vessel: 250 ml glass Erlenmeyer flasks containing 50mL of sterile medium
- No. of organisms per vessel: currently 2500 cell/ml (between 1000 and 5000 cells/mL)
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2
- No. of vessels per vehicle control (replicates): 2
- No. of vessels per blank (replicates): 1
- No of experiments: 3 definitive tests performed at minimum 5 conentrations and in duplicate

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: sterile distilled water
- Ca/mg ratio: 50 mg/l
- Culture medium different from test medium: no

OTHER TEST CONDITIONS
- Adjustment of pH: yes, pH buffered with Tris-HCl

EFFECT PARAMETERS MEASURED (with observation intervals if applicable):
The effect parameter measured was the impairment growth, with a spectrophotometric method (wavelength: 540 nm)

TEST CONCENTRATIONS
- Spacing factor for test concentrations: No data
- Range finding study: Yes, at least 2 tests

Reference substance: no data
Reference substance (positive control):
not specified

Results and discussion

Effect concentrations
Duration:
40 h
Dose descriptor:
IC50
Effect conc.:
158.7 mg/L
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Details on results:
95% CL is not given in the publication.
Results with reference substance (positive control):
no data
Reported statistics and error estimates:
IC50 is calculated with the Finney probit analysis using percent control-normalized absorbance as the dependent variable and the toxicant concentration (mg/l) as the independant variable.

Any other information on results incl. tables

Author give in the publication the value for Log (IC50-1)= 0.02 with IC50 in mM

So the calculation to deduce IC50 is as following:

IC50 =1 / [inv Log (0.02)] = 0.955 mM

IC50 = 0.955 * MW with MW = 166.175 g/mol

IC50 = 158.7 mg/L

Applicant's summary and conclusion

Validity criteria fulfilled:
not specified
Conclusions:
Ethylvanillin is not harmful for Tetrahymena pyriformis in the conditions tested.
Executive summary:

In a study (Schultz, 1997), the acute toxicity of Tetrahymena pyriformis was studied under static conditions. Microorganisms were exposed to at least 5 concentrations of Ethylvanillin.

The 40-hour IC50 was 158.7 mg/L.

Under these conditions, Ethylvanillin is not considered harmful to microorganisms tested.