Iodine pentafluoride

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

migrated information: read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Data published in a peer-reviewed journal, adequate for assessment.

Data source

Reference

Reference Type:

publication

Title:

Lack of genotoxicity of potassium iodate in the alkaline comet assay and in the cytokinesis-block micronucleus test. Comparison to potassium bromate

Author:

Poul, J.M. et al.

Year:

2004

Bibliographic source:

Food and Chemical Toxicology 42 (2004) 203–209

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Comet assay (single cell gel electrophoresis assay)

GLP compliance:

no

Type of assay:

other: Comet assay

Test material

Test material information

Constituent 1

Reference substance name:

Potassium iodate

EC Number:

231-831-9

EC Name:

Potassium iodate

Cas Number:

7758-05-6

IUPAC Name:

potassium iodate

Details on test material:

- Supplier: Acros organics
- Purity: >99%

Method

Species / strain

Species / strain / cell type:

other: Chinese hamster Ovary (CHO) K1

Details on mammalian cell type (if applicable):

Media: HAM’S F12 medium with L-glutamine supplemented with 10% fetal calf serum, penicillin (50 UI/ml) and streptomycine (50 mg/mL).

Test concentrations with justification for top dose:

Preliminary cytotoxicity assays: Concentrations ranging from 0.001 to 5 mg/mL for 1 hour.
Comet assay: Cells were exposed for 3 hours to 0.625, 1.25, 2.5, 5 and 10 mM.
Stability of iodate under exposure conditions was confirmed by analysis (titrimetric method after reduction of iodate to elemental iodine).

Vehicle / solvent:

Culture medium

Controls

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: etoposide

Details on test system and experimental conditions:

Cells were collected by trypsination, suspended in prewarmed low melting point (LMP) agarose (0.5% in PBS) and deposited on a conventional microscope slide (initially dipped in 1% agarose and dried) precoated with normal agarose (0.8% in PBS). Slides were put in a lysis solution (2.5 M NaCl, 0.1 M EDTA, 10 mM Tris pH10, 10% DMSO and 1% Triton 100) for 1 hour at about 5°C. DNA was allowed to unwind in electrophoresis buffer (0.3 M NaOH, 1 mM EDTA, pH13.6) for 40 min at room temperature. Slides were then placed into a horizontal electrophoresis tank (Hoeffer HE99) and exposed to 0.7 V/cm (300 mA) for 24 minutes. After electrophoresis, slides were washed twice in neutralization buffer (0.4 M Tris, pH7.5) and dehydrated in ethanol for 5 minutes. After staining with ethidium bromide, 50 randomly selected cells per slide were submitted to image analysis (Module CometPro4 of Aphelion software, ADCIS society, Caen, France). Each dose was tested in duplicate and at least two independent assays were performed. Etoposide (0.5 mg/mL), a well known inhibitor of topoisomerase II inducing DNA double strand breaks was used as positive control. In parallel to the assessment of DNA damage, cell viability was measured using the Trypan blue exclusion method. Cell viability was expressed as proportion of total cells.

Evaluation criteria:

Olive tail moment (OTM), defined as the product of the distance between the barycentres of the head and tail by the proportion of DNA in the tail, was used to evaluate the extent of DNA damage in individual cells. Highly damaged cells (HDC) were characterized by an extensive DNA fragmentation which allowed 90% of the DNA to migrate during electrophoresis, forming the comet tail. Median values of OTM were calculated without taking HDC into account.

Statistics:

Data were expressed as the median values of OTM (±S.D.) for each slide.
Comparisons between control and treated cell cultures were made using ANOVA and Dunnett’s one sided test.

Results and discussion

Test results

Species / strain:

not specified

Metabolic activation:

not applicable

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

CYTOTOXICITY
- Preliminary experiment: Cell mortality was found <5% with the exception of cell cultures exposed to the highest concentration (5 mg/mL) of potassium iodate (13.0%).
- None of the concentrations used in the comet assay increased the mortality over 6%.

GENOTOXICITY
- No primary DNA damage was observed after cell exposure to potassium iodate. There was a slight increase in tail moment observed for the 10 mM potassium iodate concentration, however, this was not statistically significant from control.

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
negative

Potassium iodate was not genotoxic in an alkaline comet assay with CHO cells.

Executive summary:

The genotoxic potential of potassium iodate was investigated in vitro, using the alkaline comet assay with CHO cells. No DNA damage was detected in cells exposed to potassium iodate for 3 hours to concentrations up to 10 mM.