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Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Remarks:
Strain with AT base pair missing; not tested up to the maximum test concentration for soluble non-cytotoxic substances

Data source

Reference
Reference Type:
publication
Title:
Salmonella Mutagenicity Tests: III. Results From the Tesing of 255 Chemicals
Author:
Zeiger et al.
Year:
1987
Bibliographic source:
Environ Mutagen. 9:1-109

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Version / remarks:
adopted 21 July 1997
Deviations:
yes
Remarks:
Strain with AT base pair missing; not tested up to maximum test concentration for soluble non-cytotoxic substances
GLP compliance:
no
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent

Method

Target gene:
his operon
Species / strain
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Metabolic activation:
with and without
Metabolic activation system:
cofactor supplemented post-mitochondrial fraction (S9 mix), prepared from the livers of rats and hamsters treated with Aroclor 1254.
Test concentrations with justification for top dose:
33, 100, 333, 1000 and 1820 µg/plate
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: water
Controls
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive control substance:
other: -S9: sodium azide for TA100 and TA1535; 9-aminoacridine for TA1537; 4-nitro-o-phenylendiamine for TA98; +S9: 2 aminoanthracene (2.5 or 5 µg/plate) for all strains
Details on test system and experimental conditions:
METHOD OF APPLICATION: preincubation

DURATION
- Preincubation period: 20 min
- Exposure duration: 48 h

NUMBER OF REPLICATIONS: Triplicates each in 2 independent experiments

DETERMINATION OF CYTOTOXICITY
- Method: relative total growth
Evaluation criteria:
A chemical was judged to be mutagenic or weakly mutagenic if it produced a reproducible, dose-related increase in his+ revertants over the corresponding solvent controls in replicate trials. A chemical was considered to be questionable if a reproducible increase of his+ revertants did not meet the criteria for either mutagenic or weakly mutagenic, or if only single doses produced an increase in his+ revertants in repeat trials.
Statistics:
Mean values and standard deviation were calculated.

Results and discussion

Test resultsopen allclose all
Key result
Species / strain:
other: TA 100, TAA 1535 and TA 1537
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
Key result
Species / strain:
S. typhimurium TA 98
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
-S9: ≥ 1000 µg/plate; + S9: ≥1820 µg/plate
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
Additional information on results:
RANGE-FINDING/SCREENING STUDIES: The test substance was tested inititally in a toxicity assay to determine the appropriate dose range (data not shown).

Any other information on results incl. tables

Table 1 Test Results

With or without S9-Mix Test substance concentration Mean number of revertant colonies per plate 
(μg/plate) (average of 3 plates ± Standard deviation)
  Base-pair substitution type Frameshift type
  TA 100 TA1535 TA98 TA1537
0 122 ± 24.2 5 ± 1.7 14 ± 2.5 4 ± 2.0
33 107 ± 2.9 6 ± 0.9 12 ± 0.7 5 ± 1.2
100 115 ± 14.1 6 ± 1.3 11 ± 0.3 5 ± 2.2
333 104 ± 5.5 3 ± 0.9 12 ± 0.6 5 ± 0.6
1000 100 ± 5.8 4 ± 1.2 8 ± 1.9 3 ± 0.9
1820 85 ± 9.5 4 ± 1.0 8 ± 0.9 4 ± 1.8
Positive controls, –S9 Name  SA SA 4-NOP 9-AA
Mean No. of colonies/plate (average of 3 ± SD) 571 ± 9.9 168 ± 5.9 407 ± 11.3 1088 ± 11.7
+ 0 158 ± 5.0 6 ± 2.3 26 ± 4.5 6 ± 1.8
+ 33 148 ± 12.2 4 ± 1.2 17 ± 4.2 6 ± 1.2
+ 100 161 ± 14.7 5 ± 0.6 26 ± 1.0 5 ± 1.2
+ 333 146 ± 12.7 7 ± 2.0 17 ± 1.5 4 ± 1.2
+ 1000 134 ± 28.7 5 ± 0.3 17 ± 2.6 7 ± 1.7
+ 1820 138 ± 23.6 6 ± 1.3 11 ± 2.0 5 ± 1.7
Positive controls, +S9 (rat) Name  2AA 2AA 2AA 2AA
Mean No. of colonies/plate (average of 3 ± SD) 3149 ± 19.0 80 ± 4.7 1621 ± 71.4 129 ± 9.2

Applicant's summary and conclusion

Conclusions:
Dehydroacetic acid, sodium salt DHA-Na (with or without metabolic activation) was not mutagenic in this Ames test.
Executive summary:

Dehydroacetic acid, sodium salt DHA-Na assessed in an Ames test at concentrations up to 1820µg/plate (with or without metabolic activation ) was shown to be not mutagenic.