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Toxicity to microorganisms

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Endpoint:
toxicity to microorganisms, other
Remarks:
Tetrahymena
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1994
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Qualifier:
no guideline followed
Principles of method if other than guideline:
- Principle of test: growth inhibition
GLP compliance:
no
Specific details on test material used for the study:
Each chemical (totally 20 chemicals tested) was purchased from either Aldrich Chemical Co., Milwaukee, WI, USA, or ICN Biomedicals, Inc.,
Costa Mesa, CA, USA, and each had a purity of 95% or greater.
Analytical monitoring:
no
Vehicle:
yes
Remarks:
the final DMSO concentration was not in excess of 0.35 ml per flask, an amount that does not alter Tetrahymena population growth (Schultz and Cajina-Quezada 1982).
Details on test solutions:
Stock solutions were prepared in dimethylsulfoxide (DMSO) at concentrations of 5, 10, 25, or 50 g/L.
Test organisms (species):
Tetrahymena pyriformis
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
2 d
Test temperature:
27 +- 1 °C
pH:
7.35
Details on test conditions:
TEST SYSTEM
- Test vessel: 250-ml Erlenmeyer flasks
- Fill volume: 50 ml of sterile medium.
- No. of vessels per concentration (replicates): 3
- Biomass loading rate: 2,500 cells/ml.

EFFECT PARAMETERS MEASURED:
population density measured spectrophotometrically at 540 nm

TEST CONCENTRATIONS
6--8 step concentration series.
Only replicates with control values in late log-growth-phase (absorbance from 0.6 to 0.9) were used in the analyses.
Reference substance (positive control):
no
Remarks:
Totally 26 substances tested
Key result
Duration:
2 d
Dose descriptor:
IC50
Effect conc.:
30.51 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Remarks on result:
other: 95% CI: 21.70-38.04 mg/L
Reported statistics and error estimates:
Probit Analysis of Statistical Analysis System (SAS) software (SAS Institute Inc. 1989)
Validity criteria fulfilled:
yes
Conclusions:
In a test on toxicity on Tetrahymena pyriformis 50% of the growth were inhibited at 30.51 mg/L.
Endpoint:
toxicity to microorganisms, other
Remarks:
Tetrahymena
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
1999
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Qualifier:
no guideline followed
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
no
Test organisms (species):
Tetrahymena pyriformis
Details on inoculum:
strain GL-C
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
40 h
Details on test conditions:
TEST SYSTEM
- No. of vessels per concentration (replicates): 3
- No. of vessels per vehicle control (replicates): 2

EFFECT PARAMETERS MEASURED:
population density quantitated spectrophotometrically at 540 nm as its end point

TEST CONCENTRATIONS
Six to eight different concentrations of each test material with duplicate flasks with each concentration. Only replicates with control absorbency values of >0.6 but <0.75 were used in the analyses.
Reference substance (positive control):
no
Remarks:
totally 200 substances tested
Key result
Duration:
40 h
Dose descriptor:
IC50
Effect conc.:
4 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Reported statistics and error estimates:
Probit Analysis of Statistical Analysis System (SAS) software

Toxicity value as stated in the publication: log(IGC50 -1) = 0.60

( IGC50: 50% growth inhibitory concentration)

Validity criteria fulfilled:
yes
Conclusions:
In a test on toxicity on Tetrahymena pyriformis 50% of the growth were inhibited at 4 mg/L.

Description of key information

In a test on toxicity on Tetrahymena pyriformis 50% of the growth were inhibited at 30.51 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:
30.51 mg/L

Additional information

In a further study an IGC50 value of 4 mg/L was determined.