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Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Inulinase was tested using the Ames assay.

Inulinase was not mutagenic when tested up to 9100 μg/mL in the presence and absence of metabolic activation in treat and plate assay.

Link to relevant study records
Reference
Endpoint:
in vitro gene mutation study in bacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
19-02-1982 to 17-12-1982
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
comparable to guideline study
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
GLP compliance:
no
Remarks:
Only assessed by quality assurance.
Type of assay:
bacterial reverse mutation assay
Target gene:
Histidine and tryptophan locus in the genome of five strains of bacteria
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Species / strain / cell type:
S. typhimurium TA 1538
Metabolic activation:
with and without
Metabolic activation system:
S-9 mix from Aroclor 1254-induced rat liver
Test concentrations with justification for top dose:
Preliminary test: No preliminary trials were carried out.
Six concentrations of the test item (30, 91, 303, 910, 3000, 9100 μg/mL)
Vehicle / solvent:
Vehicle for enzyme: Purified water.
Justification for choice of solvent/vehicle: Substance is water-soluble and any human exposure will be in aqueous solutions.
Solvent for the positive control: DMSO
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
9-aminoacridine
2-nitrofluorene
sodium azide
other: 2-Aminoanthracene
Details on test system and experimental conditions:
METHOD OF APPLICATION: Preincubation in suspension, followed by plating on agar plates (treat and plate method).
- Cell density at seeding (if applicable): Not stated.

DURATION
- Exposure duration, pre-incubation: The incubation mixtures were incubated with shaking at 37 ± 1°C for 3 hours (treat and plate).
- Incubation time (selective incubation): 2 days

NUMBER OF REPLICATIONS: 3

DETERMINATION OF CYTOTOXICITY
- Method: Colony counting and colony growth
Evaluation criteria:
For S. typhimurium strains TA 1535, TA 1537 , TA 1538 and TA 98 at least a doubling of these mean control values was looked for at some concentration of the test substance, if a mutagenic effect was to be suspected. For S . typhimurium TA 100, a 1.5-fold increase over control value is indicative of a mutagenic effect.
A dose related response was also looked for, but at high dose levels this relationship may be inverted. Reasons for this inversion are, for example, (1) toxicity to the bacteria generally, (2) specific toxicity to the mutants and (3) (in the case of mutagens requiring activation by liver) inhibition of foreign compound metabolising enzymes.
Statistics:
N/A
Key result
Species / strain:
S. typhimurium TA 1535
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Key result
Species / strain:
S. typhimurium TA 1537
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Key result
Species / strain:
S. typhimurium TA 98
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Key result
Species / strain:
S. typhimurium TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Key result
Species / strain:
S. typhimurium TA 1538
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS
- Water solubility: Yes
- Precipitation: Precipitation is a concentration limiting factor, but no issues were reported in this study.
- Definition of acceptable cells for analysis: Viability and gene type control.

HISTORICAL CONTROL DATA (with ranges, means and standard deviation and confidence interval (e.g. 95%)
- Negative (solvent/vehicle) historical control data: Yes.
Conclusions:
Inulinase was not mutagenic when tested up to 9100 μg/mL in the presence and absence of metabolic activation in treat and plate assay.
Executive summary:

Inulinase was tested for mutagenic activity in 5 strains of Salmonella typhimurium by treating the bacteria in liquid medium and removing inulinase prior to plating out for assay of revertant colonies (treat and plate). Inulinase concentrations tested were 30, 91, 303, 910, 3000, 9100 μg/mL. The experiment was conducted in the presence and absence of a liver preparation from male rats, pre-treated with Aroclor 1254, and the co-factors required for mixed-function oxidase activity (S-9 mix).

Inulinase was not mutagenic when tested up to 9100 μg/mL in the presence and absence of metabolic activation.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (negative)

Additional information

Justification for classification or non-classification

Not classified.