Registration Dossier

Toxicological information

Genetic toxicity: in vitro

Currently viewing:

Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Remarks:
Type of genotoxicity: gene mutation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
study is part of a 13-week study (May 1979 - August 1979) and a 2-year carcinogenesis study (January 1980 - January 1982)
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Comparable to guideline study

Data source

Referenceopen allclose all

Reference Type:
publication
Title:
Salmonella mutagenicity tests: II. results from the testing of 270 chemicals
Author:
Mortelmans K, Haworth S, Lawlor T, Speck W, Tainer B and Zeiger E
Year:
1986
Bibliographic source:
Environ. Mutagen. Suppl. 8, 1-119
Reference Type:
study report
Title:
Unnamed
Year:
1986
Report Date:
1986

Materials and methods

Principles of method if other than guideline:
Method: see: Haworth S, Lawlor T, Mortelmans K, Speck W and Zeiger E (1983).  Salmonella mutagenicity test results for 250 chemicals. Environ 
Mutagen.  5 (Suppl. 1), 3 -142.
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
other TS: Origin: Leidy Chemical Corporation 97 % pure, 0.3 % water

Method

Target gene:
mutated gene loci responsible for histidine auxotrophy
Species / strain
Species / strain / cell type:
other: Salmonella typhimurium TA98, TA100, TA1535, TA1537
Details on mammalian cell type (if applicable):
Species/cell type: from Dr. B. Ames, Univ. of California
Additional strain / cell type characteristics:
not specified
Metabolic activation:
with and without
Metabolic activation system:
Aroclor 1254-induced rat and hamster liver  fractions
Test concentrations with justification for top dose:
33, 100, 333, 1000, 3333 and 10000 (TA 1535), 100, 333, 1000, 3333, 10000 (TA 100), 33, 100, 333, 1000, 3333 (TA 98 and 1537) µg/plate
Vehicle / solvent:
water
Controls
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
Remarks:
water
True negative controls:
yes
Remarks:
potassium chloride
Positive controls:
yes
Remarks:
for details see below
Positive control substance:
other: for details see below
Remarks:
no remarks
Details on test system and experimental conditions:
Type: Ames test
ADMINISTRATION: 
- Number of replicates: 3 per dose level, repeated
- Positive and negative control groups and treatment:    
sodium azide positive for TA 1535 and TA 100, 4-nitro-o-phenylenediamine positive for TA 98, 9-aminoacridine positive for TA 97 and TA 1537,  
2-aminoanthracene positive all strains, potassium chloride negative
- Solvent: H2O
- 3 investigations were performed: 1. without MA, 2. with MA (Arochlor-1254 liver rats) 3. with MA (Arochlor-1254 liver hamster)

Cells and test compound or solvent (water) were incubated for 20 minutes at 37 °C in the presence of either S9 or buffer (0.1 M PO4, pH 7.4).
After the addition of soft agar, the contents of each tube were poured onto 25 ml of minimal glucose bottom agar. When the top agar had solidified,
the plates were inverted and incubated at 37 °C for 48 hours (Haworth et al. 1983).  The analysis was performed twice, each in triplicate.
Evaluation criteria:
1. mutagenic response: a dose-related, reproducible increase in the number of revertants over background, even if the increase was less than
twofold
2. nonmutagenic response: when no increase in the number of revertants was elicited by the chemical
3. questionable response: when there was an absence of a clear-cut-dose-related increase in revertants; when the dose-related increases in the
number of revertants were not reproducible; or when the response was of insufficient magnitude to support a determination of mutagenicity.
Statistics:
not reported

Results and discussion

Test results
Species / strain:
other: Salmonella typhimurium TA98, TA100, TA1535, TA1537
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
other: -S9: TA 100, 1535, 98 >=1000, TA 1537 >= 3333 µg/plate, +S9 (rat and hamster): only TA 1535 = 10000 µg/plate
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
GENTOXIC EFFECTS:
- With metabolic activation: None (even at cytotoxic concentrations)
- Without metabolic activation: None (even at cyctotoxic concentrations)

CYTOTOXIC CONCENTRATION:
TA 98: >= 1000 µg/plate (-S9)
TA 100: >= 1000 µg/plate (-S9)
TA 1535: >= 1000 µg/plate (-S9); 1000 µg/plate (+S9)
TA 1537: >= 3333 µg/plate (-S9)
Remarks on result:
other: other: Salmonella typhimurium TA98, TA100, TA1535, TA1537
Remarks:
Migrated from field 'Test system'.

Any other information on results incl. tables

no remarks

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
negative

Under the conditions of this study, Isophorone was not mutagenic in strains TA 100, TA 1535, TA 1537, or TA 98 of Salmonella typhimurium in the
presence or absence of Aroclor 1254-induced Sprague-Dawley male rat or male Syrian hamster liver S9.
Executive summary:

The test substance Isophorone was tested for any mutagenic activity in the Ames Salmonella/microsomes test. Four histidine-

auxotrophic Salmonella typhimurium strains TA 98, TA 100, TA 1535, and TA1537 were treated with the test item by the pre-incubation method. Dose levels covering a total range of 33 to 10000 µg/plate, in triplicate both with and without the addition of a metabolising system (Aroclor induced rat and hamster liver S9 mix) were employed.

A mutagenic activity of Isophorone to any of the five tester strains was not observed with and without metabolic activation. It is therefore concluded, that Isophorone is not a bacterial mutagen.