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Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Remarks:
Type of genotoxicity: gene mutation
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
October 23, 2012 - November 20, 2012
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The study was regarded reliable without restriction since the study was conducted according to the OECD guideline 471 and in compliance with GLP. Read-across justification: Target substance belongs into the group of substances called xanthates. The xanthates are generally prepared from the reaction of the alkoxide, which reacts with carbon disulphide to give the xanthate. These substances contain common functional group which is dithiocarbonate (-OCSS-). Though they are structural analogues with the target substance. All these analogue substances are also used in similar use application as water solutions. All xanthates decompose in the presence of water. In neutral to alkaline media, they will release carbon disulphide, particular alcohol(s) and carbonates and dithiocarbonates. Carbon disulphide is the major and the most volatile and the most hazardous decomposition product of xanthates. It is also more toxic to human health than the target substance. As the xanthates can be considered as a group of substances which have structural similarity and similar behaviour in contact with water and in the physiological processes, their irritation, sensitisation and genotoxicity properties as well as acute and systemic adverse effects to human health are similar. Therefore, and in order to avoid the unnecessary animal testing, the read-across data from the analogue xanthates is used to evaluate the irritation, sensitisation, genotoxicity and short term and/or long-term toxicological effects of the target substance. As the target substance is an unstable compound, the apparent toxicity reflects to the toxicity of the degradation products. The selection of the most critical degradation products for the hazard assessment are based on the known decomposition reaction of the target substance and based on the physicochemical properties and toxicological properties of the degradation products. The adverse effects through inhalation route are not relevant for the substance itself, which is a solid non-volatile pellet form substance. However, the most serious human health hazards are related to CS2 released from the target substance. Therefore, the formation of carbon disulphide by decomposition is the driving force for human health hazard assessment via inhalation and taken into account in DNEL derivation and in the exposure assessment of the target substance.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013
Report Date:
2013

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
no
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Test material form:
solid: pellets
Details on test material:
- Name of test material (as cited in study report): Potassium Iso-amyl Xanthate
- Physical state: solid pellets
- Analytical purity: 90.2 %
- Purity test date: July 2, 2012
- Lot/batch No.: 2012-06
- Expiration date of the lot/batch: January, 2013
- Storage condition of test material: Ambient temperature (15-25 deg. C)

Method

Species / strainopen allclose all
Species / strain / cell type:
S. typhimurium TA 97
Species / strain / cell type:
S. typhimurium TA 98
Species / strain / cell type:
S. typhimurium TA 100
Species / strain / cell type:
S. typhimurium TA 102
Species / strain / cell type:
S. typhimurium TA 1535
Metabolic activation:
with and without
Metabolic activation system:
S9
Test concentrations with justification for top dose:
A preliminary range-finding assay
- without metabolic activation (nine concentrations)
5, 2.5, 1, 0.75, 0.5, 0.1, 0.01, 0.001, 0.0001
- with metabolic activation (seven concentrations)
0.5, 0.1, 0.01, 0.001, 0.0001, 0.00001, 0.000001

Main assay
-without metabolic activation (six concentrations)
0.5, 0.1, 0.05, 0.01 0.001, 0.0001

Confirmation assay with preincubation
-without metabolic activation 8seven concentrations)
0.1, 0.01, 0.001, 0.0005, 0.0001, 0.00001, 0.000001

-with metabolic activation
0.1, 0.01, 0.001, 0.0005, 0.0001, 0.00001, 0.000001
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: water
Controlsopen allclose all
Positive controls:
yes
Positive control substance:
2-acetylaminofluorene
9-aminoacridine
2-nitrofluorene
sodium azide
mitomycin C
Untreated negative controls:
yes
Remarks:
sterile water
Statistics:
Student's t-test was used for evaluation of statistical significance of mutation frequency increase against solvent control value.

Results and discussion

Test resultsopen allclose all
Species / strain:
S. typhimurium TA 97
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
observed test item concentrations 0.5 or higher.
Vehicle controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 98
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
observed test item concentrations 0.75 or higher.
Vehicle controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
observed test item concentrations 0.5 or higher.
Vehicle controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 102
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
observed test item concentrations 0.5 or higher.
Vehicle controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 1535
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
observed test item concentrations 2.5 or higher.
Vehicle controls validity:
valid
Positive controls validity:
valid

Any other information on results incl. tables

The read-across justification is attached in IUCLID section 13.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
negative with metabolic activation
negative without metabolic activation

Potassium isoamyl xanthate was tested for mutagenic potential using in vitro bacterial reverse mutation test. The test substance did not exert mutagenic activity both in presence and absence of metabolic activation.
Executive summary:

Potassium isoamyl xanthate was tested for the mutagenic potential using in vitro bacterial reverse mutation test (Ames tes)(corresponding to the OECD No. 471). A preliminary range-finding asay was performed using five strains of Salmonella typhimurium (TA97, TA98, TA100, TA102 and TA1535) up to a maximum dose of 5.0 mg/plate to determine the optimal non-toxic test dose.

Potassium isoamyl xanthate was tested for mutagenic potential in main assay using five strains of Salmonella typhimurium in concentration range of 0.0001 -0.5 mg/plate. The test was conducted by preincubation of the test substance in the absence and presence of external matabolic activation with S9 fraction prepared from Sparague-Dawley rats.

Potassium isoamyl xanthate did not produce any significant increase of mutation frequency in these strains up to the maximum dose 5.0 mg/plate both in the absence or presence of metabolic activation. Based on the study results the test substance is considered to be non-mutagenic.

The test result is used as a key value in the hazard assessment.