Sodium periodate

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Ames test; in vitro micronucleus test (mouse bone marrow): Negative (sodium iodate). All in vitro studies were performed without metabolic activation.

In vitro alkaline comet assay; in vitro cytokinesis-block micronucleus assay: Negative (potassium iodate)

Mouse lymhoma assay: Negative; BALB/c 3T3transformation assay: Negative (potassium iodide)

Link to relevant study records

Reference

Reference 1

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

not reported

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Remarks:

Data from a report from a recognised body reviewed by a panel of experts. Although there is limited detail on materials and methods included in the publication, the conclusions drawn from the CICADS document are considered to be reliable and representative of the mutagenic potential of the substance.

Reason / purpose for cross-reference:

other: read across: target

Qualifier:

no guideline available

Principles of method if other than guideline:

An Ames test was conducted although the publication includes no detail on the materials and methods used in the study.

GLP compliance:

not specified

Type of assay:

bacterial reverse mutation assay

Key result

Species / strain:

not specified

Metabolic activation:

not specified

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Sodium iodate showed no mutagenic activity by the Ames test.

Conclusions:

Interpretation of results: negative

The publication reported that sodium iodate showed no mutagenic activity by the Ames test.

Executive summary:

The publication reported that sodium iodate showed no mutagenic activity by the Ames test. No information is provided on experimental materials and methods.

Reference 2

Endpoint:

in vitro cytogenicity / micronucleus study

Type of information:

experimental study

Adequacy of study:

key study

Study period:

not reported

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Remarks:

Data from a report from a recognised body reviewed by a panel of experts. Although there is limited detail on materials and methods included in the publication, the conclusions drawn from the cicads document are considered to be reliable and representative of the mutagenic potential of the substance.

Reason / purpose for cross-reference:

other: read across: target

Qualifier:

no guideline available

Principles of method if other than guideline:

A micronucleus test was conducted although the publication includes no detail on the materials and methods used in the study.

GLP compliance:

not specified

Type of assay:

in vitro mammalian cell micronucleus test

Species / strain / cell type:

mammalian cell line, other: mouse bone marrow

Key result

Species / strain:

mammalian cell line, other: mouse bone marrow

Metabolic activation:

not specified

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Sodium iodate showed no mutagenic activity by the micronucleus test using mouse bone marrow.

Conclusions:

Interpretation of results: negative

The publication reported that sodium iodate showed no mutagenic activity by the micronucleus test using mouse bone marrow. No information is provided on experimental materials and methods.

Executive summary:

The publication reported that sodium iodate showed no mutagenic activity by the micronucleus test using mouse bone marrow.

No information is provided on experimental materials and methods.

Reference 3

Endpoint:

in vitro DNA damage and/or repair study

Type of information:

experimental study

Adequacy of study:

key study

Study period:

not reported

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

The study was conducted on the read across substance, potassium iodate. Investigations on the gastric hydrolysis of the registration substance indicate a chemical reaction of periodate to iodate thereby confirming the validity of the read across.

Reason / purpose for cross-reference:

other: read across: target

Qualifier:

no guideline available

Principles of method if other than guideline:

The alkaline comet assay was performed according to Tice et al. (2000). Cells were collected by trypsination, suspended in pre-warmed low melting point (LMP) agarose (0.5 % in PBS) and deposited on a conventional microscope slide (initially dipped in 1 % agarose and dried) pre-coated 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, pH 13.6) for 40 minutes at room temperature. Slides were then placed into a horizontal electrophoresis tank 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, pH 7.5) and dehydrated in ethanol for 5 minutes. After staining with ethidium bromide, 50 randomly selected cells per slide were submitted to image analysis. 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 characterised 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. 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.

GLP compliance:

not specified

Type of assay:

comet assay

Species / strain / cell type:

Chinese hamster Ovary (CHO)

Details on mammalian cell type (if applicable):

Chinese hamster ovary (CHO-K1) cells were purchased from Eurobio (France). They were routinely maintained from stocks stored in liquid nitrogen. CHO cells were grown at 37 °C in a humidified atmosphere at 5% CO2 in air, in HAM’S F12 medium with L-glutamine supplemented with 10 % fetal calf serum (FCS), penicillin (50 UI/mL) and streptomycine (50 mg/mL). Cells were subcultured 24 hours before treatment.

Test concentrations with justification for top dose:

0.625, 1.25, 2.5, 5 and 10 mM

Vehicle / solvent:

For test material formulations culture medium was used as vehicle.
For positive control Etoposide (0.5 mg/mL) was dissolved in DMSO.

Untreated negative controls:

yes

Remarks:

culture medium

Negative solvent / vehicle controls:

no

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: Etoposide

Details on test system and experimental conditions:

The alkaline comet assay was performed according to Tice et al. (2000). Cells were collected by trypsination, suspended in pre-warmed low melting point (LMP) agarose (0.5 % in PBS) and deposited on a conventional microscope slide (initially dipped in 1 % agarose and dried) pre-coated 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, pH 13.6) for 40 minuttes at room temperature. Slides were then placed into a horizontal electrophoresis tank 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, pH 7.5) and dehydrated in ethanol for 5 minutes. After staining with ethidium bromide, 50 randomly selected cells per slide were submitted to image analysis.
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.

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 characterised 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.
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.

Statistics:

In the alkaline comet assay, 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.

Key result

Species / strain:

Chinese hamster Ovary (CHO)

Remarks:

CHO-K1

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:

The results showed that the comet assay failed to detect the presence of DNA damage after a treatment of cells by potassium iodate for concentrations up to 10 mM.
The slight increase in tail moment observed at 10 mM was found not to be statistically singificant from the control.

Conclusions:

Interpretation of results: negative

Under the conditions of the study, potassium iodate had no clastogenic activity in CHO cells for concentrations up to 10 mM.

Executive summary:

The mutagenic effects of potassium iodate were evaluated in vitro using the alkaline comet assay at concentration of 0.625, 1.25, 2.5, 5 and 10 mM. Cell viability was measured using the Trypan blue exclusion method and expressed as proportion of total cells. The test results showed that potassium iodate did not induce DNA damage, or cytotoxicity, in the alkaline comet assay for doses up to 10 mM.

Reference 4

Endpoint:

in vitro cytogenicity / micronucleus study

Type of information:

experimental study

Adequacy of study:

key study

Study period:

not reported

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

The study was conducted on the read across substance, potassium iodate. Investigations on the gastric hydrolysis of the registration substance indicate a chemical reaction of periodate to iodate thereby confirming the validity of the read across.

Reason / purpose for cross-reference:

other: read across: target

Qualifier:

equivalent or similar to guideline

Guideline:

other: OECD Guideline 487 (In Vitro Mammalian Cell Micronucleus Test)

Deviations:

yes

Remarks:

all cultures were treated without metabolic activation

Principles of method if other than guideline:

Exponentially growing CHO-K1 cells were plated in a six-well plate on glass coverslips (1.5105 cells/well) and cultured 24 hours prior to treatment. Duplicate coverslips were established for each experiment, and at least two independent experiments were performed. The cells were exposed to the test material at different concentrations for 3 hours in a Foetal Calf Serum (FCS) free medium. At the end of treatment, cells were washed twice with Phosphate Buffered Saline (PBS) before a 20 hour incubation in fresh medium containing 10 % of FCS and 3 mg/mL of cytochalasin B. Thereafter, cells were washed twice with PBS and allowed to recover for 1.5 hours in 10 % FCS fresh medium. Cells were fixed with cold methanol, stained with acridine orange (62.5 mg/mL) for 5 minutes and mounted in Sorensen buffer. Slides were coded and blindly examined under an epifluorescence microscope at 1000 magnification under oil immersion. One thousand (1000) binucleated cells were scored for each slide. Methyl methanesulphonate (MMS) (30 mg/mL), a well known alkylating agent, was used as positive control. Cytotoxicity was measured by the binucleated cell ratio between treated and control slides.

GLP compliance:

not specified

Type of assay:

in vitro mammalian cell micronucleus test

Species / strain / cell type:

Chinese hamster Ovary (CHO)

Details on mammalian cell type (if applicable):

Chinese hamster ovary (CHO-K1) cells were purchased from Eurobio (France). They were routinely maintained from stocks stored in liquid nitrogen. CHO cells were grown at 37 °C in a humidified atmosphere at 5% CO2 in air, in HAM’S F12 medium with L-glutamine supplemented with 10 % fetal calf serum (FCS), penicillin (50 UI/mL) and streptomycine (50 mg/mL). Cells were subcultured 24 hours before treatment.

Test concentrations with justification for top dose:

0.625, 1.25, 2.5, 5 and 10 mM

Vehicle / solvent:

For test material formulations culture medium was used as vehicle.
For positive control, methyl methanesulphonate (MMS) (30 µg/mL) was dissolved in culture medium.

Untreated negative controls:

yes

Remarks:

culture medium

Negative solvent / vehicle controls:

no

True negative controls:

no

Positive controls:

yes

Positive control substance:

methylmethanesulfonate

Details on test system and experimental conditions:

Exponentially growing CHO-K1 cells were plated in a six-well plate on glass coverslips (1.5105 cells/well) and cultured 24 hours prior to treatment. Duplicate coverslips were established for each experiment, and at least two independent experiments were performed. The cells were exposed to the test material at different concentrations for 3 hours in a Foetal Calf Serum (FCS) free medium. At the end of treatment, cells were washed twice with Phosphate Buffered Saline (PBS) before a 20 hour incubation in fresh medium containing 10 % of FCS and 3 mg/mL of cytochalasin B. Thereafter, cells were washed twice with PBS and allowed to recover for 1.5 hours in 10 % FCS fresh medium. Cells were fixed with cold methanol, stained with acridine orange (62.5 mg/mL) for 5 minutes and mounted in Sorensen buffer.

Evaluation criteria:

Slides were coded and blindly examined under an epifluorescence microscope at 1000 magnification under oil immersion. Criteria for cells and micronuclei scoring were as follows:
- The cells should be binucleated with an intact nuclear membrane and should be situated within the same cytoplasmic boundary.
- Micronuclei should be morphologically identical to but smaller than nuclei, their diameter usually varied between 1/6th and 1/3rd of the mean diameter of the main nuclei.
- Micronuclei should be readily distinguished and not be linked to the main nuclei via nucleoplasmic bridges.
- Cells showing chromatin condensation or nuclear fragmentation with an intact cytoplasmic membrane were classified as apoptotic cells.
One thousand (1000) binucleated cells were scored for each slide. The frequencies of binuclei, or binuclei with micronuclei and of apoptotic cells were estimated. Cytotoxicity was measured by the bincleated cell ratio between treated and control slides.

Statistics:

In the cytokinesis-block micronucleus assay data were expressed as the percentage of binucleated cells with micronuclei. Comparisons between control and treated cell cultures were made using ANOVA and Dunnett’s one sided test.

Key result

Species / strain:

Chinese hamster Ovary (CHO)

Remarks:

CHO-K1

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:

Potassium iodate did not induce any increase in the frequency of binucleated cells with micronuclei for doses ranging from 0.625 to 10 mM. Furthermore, no clastogenic effects of the compound were noted in cells that had completed one nuclear division.

Conclusions:

Interpretation of results: negative

Potassium iodidate had no significant chromosome damaging effects in the cytokinesis-block micronucleus test. No clastogenicity was noted.

Executive summary:

The mutagenic potential of the test material was investigated in a cytokinesis-block micronucleus assay at test concentrations of 0.625, 1.25, 2.5, 5 and 10 mM. Concurrent positive and negative controls were included. Under the conditions of the study, potassium iodate did not induce any increase in the frequency of binucleated cells with micronuclei for doses ranging from 0.625 to 10 mM. Furthermore, no clastogenic effects of the compound were noted in cells that had completed one nuclear division.

Reference 5

Endpoint:

in vitro gene mutation study in mammalian cells

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

Not reported

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

The study was conducted with the read across substance, potassium iodide. Investigations on the gastric hydrolysis of the registration substance indicate a chemical reaction of periodate to iodate, while toxicokinetic investigations on iodate indicate a chemical reaction of iodate to iodide, thereby confirming the validity of the read across.

Reason / purpose for cross-reference:

other: read across: target

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 476 (In Vitro Mammalian Cell Gene Mutation Test)

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method B.21 (In Vitro Mammalian Cell Transformation Test)

GLP compliance:

no

Remarks:

Study pre-dates GLP

Type of assay:

mammalian cell gene mutation assay

Target gene:

thymidine kinase (TK) locus

Species / strain / cell type:

mouse lymphoma L5178Y cells

Details on mammalian cell type (if applicable):

The L5178Y mouse-lymphoma cells were originally derived from a methylcholanthrene induced lymphoma (Fischer, 1958). The L5178Y cell line used was supplied by the Food and Drug Administration, Washington, D.C, USA.

Species / strain / cell type:

other: BALB/c 3T3

Details on mammalian cell type (if applicable):

Balb/c 3T3 cells (Litton Bionetics, Kensington, Maryland, USA.), derived from done A31 of the Balb/c 3T3 line, were used for the transformation studies. The cells were grown in Eagle's Minimal Essential Medium with Eagle's- Salts (EMEM), supplemented with 10% fetal calf serum and 1 % 200 mM glutamine (Gibco). Stock cultures were maintained at 75% confluence. The maintenance medium was EMEM with 5% fetal calf serum.

Metabolic activation:

without

Metabolic activation system:

Iodide is small ion, so the metabolic activation system is unnecessary to the test

Test concentrations with justification for top dose:

- Mutagenicity test: 0.1, 0.5, 1, 5 and 10 mg/mL
- Transformation test: 0.1, 0.5, 1, 5 and 10 mg/mL

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: water

Untreated negative controls:

yes

Remarks:

media

Negative solvent / vehicle controls:

no

True negative controls:

no

Positive controls:

yes

Positive control substance:

N-dimethylnitrosamine

N-ethyl-N-nitro-N-nitrosoguanidine

ethylmethanesulphonate

Details on test system and experimental conditions:

Mutagenesis:
L5178Y cells (l x 10^6 cells/mL) in 50 mL sterile centrifuge tubes were incubated with the test compounds, EMS, MNNG, and DMN (the positive controls) or media (the negative control) for four hours at 37 °C. The cells were then washed three times in FMO and incubated in a roller drum for 48 hours. This incubation period allowed for the expression of induced mutations. The cells were then plated in FM with 20 % horse serum. To the media, 3.5 % Noble agar and 100 μg/mL BUdR were added. Colony formation was scored after 10 days incubation at 37 °C. In all of the experiments, the cloning efficiency of the control plates was found to be greater than 85 %. The number of mutant colonies / 1 x 10^3 cells was calculated for the media controls. The actual spontaneous mutation frequency was variable ranging for this series of experiments from 4-10 mutants/1 x 10^3 cells. For the purpose of calculations, this was designated as having a mutational frequency (MF) of one. All other mutational values were compared to this control value. A-MF of 2.5 or greater was considered a positive mutational event.

Transformation:
Doses of the compounds were tested for cytoxicity by plating 2 x 10^2 cells in 25 cm² tissue culture flasks (Falcon). The plating efficiency of the control was compared to that of the treated cells after seven days incubation. the doses that yielded 50 % of the control value and the next two lower dose multiples were used in the transformation assay. Ten thousand 3T3 cells were incubated for 48 hours with the test agents, MNNG (positive control) or media (negative control) in 25 cm² flasks. The cell sheet was then rinsed three times using Hank's Balanced Salt Solution (HBSS), and 5 mL of maintenance media was added to each flask. The cells were incubated for 21 days at 37 °C During this time the media was replaced twice weekly. After this incubation the cells were stained. Transformed foci were then counted. The number of foci formed in the presence of the test compounds were compared to the media control values. Only foci that exhibited the typical criss-cross pattern with overlapping and piling up of cells were considered to be transformed. Values of 2.5 times greater than that observed in the negative controls were considered to be positive transformational events.

Evaluation criteria:

Mutagenesis: All other mutational values were compared to this control value. A-MF of 2.5 or greater was considered a positive mutational event.

Transformation: Only foci that exhibited the typical criss-cross pattern with overlapping and piling up of cells were considered to be transformed. Values of 2.5 times greater than that observed in the negative controls were considered to be positive transformational events.

Statistics:

Student's T -Test was used to compare the difference between toxic group with negative control group.

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not determined

Vehicle controls validity:

not applicable

Untreated negative controls validity:

valid

Positive controls validity:

valid

Species / strain:

other: BALB/c 3T3

Metabolic activation:

without

Genotoxicity:

other: no transforming activity

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

not applicable

Untreated negative controls validity:

valid

Positive controls validity:

valid

Table 1: Mutagenicity of Iodide in the L5178Y Test System

Compound	Concentration	Mutational Frequency
Iodide (KI solution)	10 mg/mL	1
	5 mg/mL	0.76
	1 mg/mL	1.33
	500 μg/mL	1.67
	100 μg/mL	1
Negative control (Media)		1
EMS	500 μg/mL	12
MNNG	5 μg/mL	15

Table 2:  Effects of Iodide on the Transformation of Balb/c 313 Cells

Compound	Concentration	# of foci
Iodide (KI solution)	10 mg/mL	0.33
	5 mg/mL	2
	1 mg/mL	0.61
	500 μg/mL	0.61
	100 μg/mL	0.83
Negative control (Media)		1.22
MNNG	5 μg/mL	7.5

 

Conclusions:

Interpretation of results: negative in both mutagenicity and BALB/c 3T3 cell transformation assays

Under the conditions of the study, solutions of potassium iodide at concentrations of 0.1–10 mg/mL did not cause mutagenic effects in L5178Y mouse lymphoma cells or transforming activity in Balb/c3T3 cells grown in culture.

Executive summary:

The mutagenic potential to iodide was studied using the L5178Y mouse (TK+/-) lymphoma assay. The established mutagens ethylmethanesulphonate (EMS) and dimethylnitrosamine (DMN) were highly active in this assay, whereas iodide (KI) was inactive. Using the BALB/c3T3 transformation assay, the transformational capacities of these same agents, and the positive mutagen N-ethyl-N-nitro-N-nitrosoguanidine (MNNG), were assessed. All concentrations of the iodide tested were inactive in this assay. It can be concluded that potassium iodide did not possess any biologically significant mutagenic or cell transforming ability.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Description of key information

Recessive lethal test (Drosophila): Negative (sodium iodate)

Link to relevant study records

Reference

Endpoint:

in vivo insect germ cell study: gene mutation

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

not reported

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Remarks:

Data from a report from a recognised body reviewed by a panel of experts. Although there is limited detail on materials and methods included in the publication, the conclusions drawn from the cicads document are considered to be reliable and representative of the mutagenic potential of the substance.

Reason / purpose for cross-reference:

other: read across: target

Qualifier:

no guideline available

GLP compliance:

not specified

Type of assay:

Drosophila SLRL assay

Species:

Drosophila melanogaster

Details on test animals or test system and environmental conditions:

No further information provided on test animals and environmental conditions.

Additional information on results:

Sodium iodate showed no mutagenic activity by the recessive lethal test using Drosophila.

Conclusions:

Interpretation of results: negative

The publication reported that sodium iodate showed no mutagenic activity by the recessive lethal test using Drosophila. No information is provided on experimental materials and methods.

Executive summary:

The publication reported that sodium iodate showed no mutagenic activity by the recessive lethal test using Drosophila. No information is provided on experimental materials and methods.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Additional information

A collection of mutagenicity studies are provided on the read across substances: sodium iodate, potassium iodate and potassium iodide. Investigations on the gastric hydrolysis of the registration substance indicate a chemical reaction of periodate to iodate, while toxicokinetic investigations on iodate indicate a chemical reaction of iodate to iodide, thereby confirming the validity of the read across from both iodate and iodide. All of the available in vitro studies have been performed without metabolic activation. However, this is not thought to affect the overall conclusions on the genetic toxicity of sodium periodate, as the reduction of iodate in the body was demonstrated not to be enzymic in the available toxicokinetic data.

Key data are available in a report from a recognised body reviewed by a panel of experts (CICADS, 2009). Although there is limited detail on materials and methods, the conclusions drawn are considered to be reliable and representative of the mutagenic potential of the substance. The following data were therefore assigned a reliability score of 2 according to the criteria of Klimisch (1997).

The publication reported that sodium iodate showed no mutagenic activity in vitro by either the Ames test or the micronucleus test using mouse bone marrow. Furthermore, the publication reported that sodium iodate showed no mutagenic activity in vivo by the recessive lethal test using Drosophila. No information is provided on experimental materials and methods.

 

Additional data are available in a report detailing findings of an alkaline comet assay and a cytokinesis-block micronucleus assay (Poul et al., 2004). Both assays were performed to sound scientific principles with a sufficient level of detail to assess the quality of the relevant results. The following data were assigned a reliability score of 2 according to the criteria of Klimisch (1997).

 

In the first assay, the mutagenic effects of potassium iodate were evaluated in vitro using the alkaline comet assay at concentration of 0.625, 1.25, 2.5, 5 and 10 mM. Cell viability was measured using the Trypan blue exclusion method and expressed as proportion of total cells. The test results showed that potassium iodate did not induce DNA damage, or cytotoxicity, in the alkaline comet assay for doses up to 10 mM.

 

In the second assay, the mutagenic potential of the test material was investigated in a cytokinesis-block micronucleus assay at test concentrations of 0.625, 1.25, 2.5, 5 and 10 mM. Concurrent positive and negative controls were included. Under the conditions of the study, potassium iodate did not induce any increase in the frequency of binucleated cells with micronuclei for doses ranging from 0.625 to 10 mM. Furthermore, no clastogenic effects of the compound were noted in cells that had completed one nuclear division.

Supporting data on potassium iodide are presented. Results are taken from a publication in which reports on studies assessing the mutagenic potential to iodide using the L5178Y mouse (TK+/-) lymphoma assay together with a BALB/c 3T3 transformation assay.

The established mutagens ethylmethanesulphonate (EMS) and dimethylnitrosamine (DMN) were highly active in the mouse lymphoma assay, whereas iodide (KI) was inactive. Using the BALB/c 3T3 transformation assay, the transformational capacities of these same agents, and the positive mutagen N-ethyl-N-nitro-N-nitrosoguanidine (MNNG), were assessed. All concentrations of the iodide tested were inactive in this assay. It can be concluded that potassium iodide did not possess any biologically significant mutagenic or cell transforming ability.

Both assays were performed to sound scientific principles with a sufficient level of detail to assess the quality of the relevant results. and were assigned a reliability score of 2 according to the criteria of Klimisch (1997).

Justification for classification or non-classification

In accordance with the criteria for classification as defined in Annex I, Regulation 1272/2008, the substance does not require classification for genetic toxicity.