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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Ecotoxicological information

Toxicity to microorganisms

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Administrative data

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: Study meets generally accepted scientific principles but the publication reports several chemicals, therefore exhaustive details are not provided.
Principles of method if other than guideline:
The method was carried out under sterile conditions. Tetrahymena pyriformis was pre-cultured at 30 ºC for 24 h. The stock solution of the chemical was added to the sterile medium to provide a concentration ratio of 1.8 in 10 ml of 2% proteose peptone. The solutions were then inoculated with 0.2 mL of pre-cultured T. pyriformis and cultivated at 30 ºC for 24 h without agitation. The number of cells was then counted.
GLP compliance:
not specified
Analytical monitoring:
not specified
Vehicle:
yes
Details on test solutions:
Several chemicals were tested: a stock solution of each test chemical at high concentration was prepared and stored in a refrigerator. Water-soluble chemicals were dissolved directly in water; those only slightly soluble in water were dissolved in dimethylsulfoxide (DMSO). DMSO did not affect the growth of T. pyriformis at 10000 mg/L and the test was carried out at a concentration of < 5000 mg/L. Since BHT is slightly soluble in water it can be assumed that DMSO was used as vehicle.
Test organisms (species):
Tetrahymena pyriformis
Details on inoculum:
Tetrahymena pyriformis was preserved in a sterile medium of 2% proteose peptone at 20 ºC which was renewed at 2-4 week intervals.
Test type:
static
Water media type:
freshwater
Total exposure duration:
24 h
Reference substance (positive control):
not specified
Key result
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
1.7 mg/L
Nominal / measured:
not specified
Conc. based on:
test mat. (dissolved fraction)
Basis for effect:
growth inhibition
Validity criteria fulfilled:
not specified
Conclusions:
The 24 -h EC50 for the substance dibutylhydroxytoluene (BHT) in Tetrahymena pyriformis was 1.7 mg/L.
Executive summary:

A study to assess the toxicity of BHT to the aquatic protozoa Tetrahymena pyriformis was conducted. The experimental animals were pre-cultured at 30 ºC for 24 h. The stock solution of the chemical was added to the sterile medium to provide a concentration ratio of 1.8 in 10 mL of 2% proteose peptone. The solutions were then inoculated with 0.2 ml of pre-cultured T. pyriformis and cultivated at 30 ºC for 24 h without agitation. The number of cells was then counted. The relative growth rate was calculated as the ratio of the number of cells cultured wth a chemical against the number cultivated in a blank. The effective concentration 50% (EC50) values were obtained by plotting the relative growth rates against the concentration of chemical on logarithmic-probability paper. The 24 -hour EC50 for BHT was 1.7 mg/L.

Description of key information

Tetrahymena pyriformis. EC50 (24h)= 1.7 mg/L based on growth inhibition.

The 30min-EC50 of BHT to Photobacterium phosphoreum based on light emission is 8.98 mg/L.

The 36h-NOEC of BHT to Pseudomona fluorescens based on the number of viable cells was 50 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:
1.7 mg/L

Additional information

Weight of evidence

Tetrahymena pyriformis. EC50 (24h)= 1.7 mg/L based on growth inhibition.

The 30min-EC50 of BHT to Photobacterium phosphoreum based on light emission is 8.98 mg/L.

The 36h-NOEC of BHT to Pseudomona fluorescens based on the number of viable cells was 50 mg/L.