Acetic acid, (ethylenedinitrilo)tetra-, cobalt salt

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Link to relevant study records

Reference

Reference 1

Endpoint:

in vitro gene mutation study in mammalian cells

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Justification for type of information:

The study is well-documented by the publication and thus acceptable for assessment.

Principles of method if other than guideline:

Induction of TK mutations in mouse lymphoma cells (L5178Y/TK+/- to TK-/-). Treatment was for 3 hrs in the absence of metabolic activation

GLP compliance:

not specified

Type of assay:

in vitro mammalian cell gene mutation tests using the thymidine kinase gene

Target gene:

thymidine kinase locus

Species / strain / cell type:

mouse lymphoma L5178Y cells

Details on mammalian cell type (if applicable):

soft-agar media containing RPMI-1640, 10% horse serum, no antibiotics, 1mM sodium pyruvate, 0.02% (w/v) Pluronic F-68 and 0.37% Difco Bacto agar

Additional strain / cell type characteristics:

not specified

Metabolic activation:

without

Test concentrations with justification for top dose:

5.69 - 57.11 µg/ml
6 cultures treated with metal compound and 3 solvent controls

Vehicle / solvent:

saline

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

not specified

Details on test system and experimental conditions:

3 hours at 37°C treatment, following 48 hours at 37°C expression period
incubation for 7 days in TFT containing medium (4µg/mL)

Key result

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not specified

Positive controls validity:

not specified

Conclusions:

The test substance cobalt dichloride hexahydrate did not induce gene mutations in mouse lymphoma cells at the given concentrations and under the conditions applied in the test.

Reference 2

Endpoint:

in vitro gene mutation study in mammalian cells

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Justification for type of information:

The complex EDTA-CoH2 consist of the organic moiety EDTA, the central atom Co2+ and the hydrogen ions. As the latter are known to be non-toxic only the EDTA-Co complex must be regarded as toxic. For both, free EDTA and Co2+ compounds well-documented studies are available, which shows their toxicity. In general, the complex with the chelated Co2+ ion can be considered as less toxic than the free Co2+ ion due to retarded release. Based on that and that the complex EDTA-Co has an average stability, a worst-case assessment where the EDTA-CoH2 complex dissociate in its components can be done and so a read-across is possible to free EDTA and Co2+ salts.

Reason / purpose for cross-reference:

read-across source

Principles of method if other than guideline:

Induction of TK mutations in mouse lymphoma cells (L5178Y/TK+/- to TK-/-). Treatment was for 3 hrs in the absence of metabolic activation

GLP compliance:

not specified

Type of assay:

in vitro mammalian cell gene mutation tests using the thymidine kinase gene

Target gene:

thymidine kinase locus

Species / strain / cell type:

mouse lymphoma L5178Y cells

Details on mammalian cell type (if applicable):

soft-agar media containing RPMI-1640, 10% horse serum, no antibiotics, 1mM sodium pyruvate, 0.02% (w/v) Pluronic F-68 and 0.37% Difco Bacto agar

Additional strain / cell type characteristics:

not specified

Metabolic activation:

without

Test concentrations with justification for top dose:

5.69 - 57.11 µg/ml
6 cultures treated with metal compound and 3 solvent controls

Vehicle / solvent:

saline

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

not specified

Details on test system and experimental conditions:

3 hours at 37°C treatment, following 48 hours at 37°C expression period
incubation for 7 days in TFT containing medium (4µg/mL)

Key result

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not specified

Positive controls validity:

not specified

Conclusions:

The test substance cobalt dichloride hexahydrate did not induce gene mutations in mouse lymphoma cells at the given concentrations and under the conditions applied in the test.

Reference 3

Endpoint:

in vitro cytogenicity / micronucleus study

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Justification for type of information:

The study is well-documented by the publication and thus acceptable for assessment.

Principles of method if other than guideline:

Investigation on the micronucleus induction in Syrian hamster embryo (SHE) cells. The cells were treated for 24 hr in the presence of cytochalasin B (in the absence of metabolic activation). Toxicity was determined both by trypan blue exclusion and percentage of binucleate cells.

GLP compliance:

not specified

Type of assay:

in vitro mammalian cell micronucleus test

Species / strain / cell type:

other: Syrian hamster embryo (SHE) cell

Details on mammalian cell type (if applicable):

For the in vitro micronucleus test, the cells were seeded at 1x 10^6 cells/T-25 flask for control, and chemically-treated cultures. The incubation time was 24 hours.

Additional strain / cell type characteristics:

not specified

Metabolic activation:

without

Test concentrations with justification for top dose:

1, 2 and 4 µg/mL

Vehicle / solvent:

Media was the solvent - concentration of DMSO in each sample was approximately 0.3%

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: colchicine

Remarks:

0.5 µg/mL

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

cyclophosphamide

Remarks:

5 µg/mL

Details on test system and experimental conditions:

In each treatment group, 500 cells were analysed to determine the percentage of binucleated cells and 1000 binucleated cells were analysed to determine the number of micronucleated cells. Only cells with distinct cytoplasm and distinct binucleation were analysed for the presence of micronuclei. Only micronuclei that were entirely inside the cytoplasm, separate from the main nucleus, less than approximately one-third the size of the main nuclei, and non-refractile were recorded.

Statistics:

The number of micronucleated binucleated cells (MNBC) in the treated group was compared to the number of MNBC in the vehicle control group using a one-sided Fisher's exact test where p<=0.05 was considered significant.

Key result

Species / strain:

other: Syrian hamster embryo (SHE) cells

Metabolic activation:

without

Genotoxicity:

positive

Remarks:

Test substance induced a dose-dependent, significant increase in the percentage of MNBC.

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Conclusions:

Positive result, the test substance cobalt sulfate hydrate was determined to be clastogenic under the given experimental conditions.

Reference 4

Endpoint:

in vitro cytogenicity / micronucleus study

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Justification for type of information:

The complex EDTA-CoH2 consist of the organic moiety EDTA, the central atom Co2+ and the hydrogen ions. As the latter are known to be non-toxic only the EDTA-Co complex must be regarded as toxic. For both, free EDTA and Co2+ compounds well-documented studies are available, which shows their toxicity. In general, the complex with the chelated Co2+ ion can be considered as less toxic than the free Co2+ ion due to retarded release. Based on that and that the complex EDTA-Co has an average stability, a worst-case assessment where the EDTA-CoH2 complex dissociate in its components can be done and so a read-across is possible to free EDTA and Co2+ salts.

Reason / purpose for cross-reference:

read-across source

Principles of method if other than guideline:

Investigation on the micronucleus induction in Syrian hamster embryo (SHE) cells. The cells were treated for 24 hr in the presence of cytochalasin B (in the absence of metabolic activation). Toxicity was determined both by trypan blue exclusion and percentage of binucleate cells.

GLP compliance:

not specified

Type of assay:

in vitro mammalian cell micronucleus test

Species / strain / cell type:

other: Syrian hamster embryo (SHE) cell

Details on mammalian cell type (if applicable):

For the in vitro micronucleus test, the cells were seeded at 1x 10^6 cells/T-25 flask for control, and chemically-treated cultures. The incubation time was 24 hours.

Additional strain / cell type characteristics:

not specified

Metabolic activation:

without

Test concentrations with justification for top dose:

1, 2 and 4 µg/mL

Vehicle / solvent:

Media was the solvent - concentration of DMSO in each sample was approximately 0.3%

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: colchicine

Remarks:

0.5 µg/mL

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

cyclophosphamide

Remarks:

5 µg/mL

Details on test system and experimental conditions:

In each treatment group, 500 cells were analysed to determine the percentage of binucleated cells and 1000 binucleated cells were analysed to determine the number of micronucleated cells. Only cells with distinct cytoplasm and distinct binucleation were analysed for the presence of micronuclei. Only micronuclei that were entirely inside the cytoplasm, separate from the main nucleus, less than approximately one-third the size of the main nuclei, and non-refractile were recorded.

Statistics:

The number of micronucleated binucleated cells (MNBC) in the treated group was compared to the number of MNBC in the vehicle control group using a one-sided Fisher's exact test where p<=0.05 was consindered significant.

Key result

Species / strain:

other: Syrian hamster embryo (SHE) cells

Metabolic activation:

without

Genotoxicity:

positive

Remarks:

Test substance induced a dose-dependent, significant increase in the percentage of MNBC.

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Conclusions:

Positive result, the test substance cobalt sulfate hydrate was determined to be clastogenic under the given experimental conditions.

Reference 5

Endpoint:

in vitro cytogenicity / micronucleus study

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Justification for type of information:

The study is well-documented by the publication and thus acceptable for assessment.

Principles of method if other than guideline:

Induction of micronuclei (MN) in human leukocytes using the cytokinesis block method. Cells were treated for 15 minutes in the absence of metabolic activation starting 24 hr after PHA (phytohaemagglutinin) stimulation. Cells were harvested for the MN test after a total of 72 hr in culture.

GLP compliance:

not specified

Type of assay:

in vitro mammalian cell micronucleus test

Specific details on test material used for the study:

99.87% purity
median particle size (d50): 4 µm

Species / strain / cell type:

other: Leukocytes

Details on mammalian cell type (if applicable):

human volunteer age <= 30 years, healthy status
24h PHA stimulation (2%) prior to exposure
culture medium: Ham's F10 containing 15% foetal calf serum (FCS)

Additional strain / cell type characteristics:

not specified

Metabolic activation:

without

Test concentrations with justification for top dose:

0.6, 1.2, 3.0 and 6.0 µg/mL

Vehicle / solvent:

water (10 µL)

Positive controls:

yes

Positive control substance:

mitomycin C

Key result

Species / strain:

other: Leukocytes

Metabolic activation:

without

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

not specified

Untreated negative controls validity:

not specified

Positive controls validity:

not specified

Conclusions:

The result was positive for the test substance extra fine cobalt metal powder. Although the treatment time was short, and cells were not in exponential growth at the time of treatment, this is a reasonably robust study by current standards. A significant induction (>2-fold) in MN frequency at concentrations from 0.6 µg/ml and higher could be observed.

Reference 6

Endpoint:

in vitro cytogenicity / micronucleus study

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Justification for type of information:

The complex EDTA-CoH2 consist of the organic moiety EDTA, the central atom Co2+ and the hydrogen ions. As the latter are known to be non-toxic only the EDTA-Co complex must be regarded as toxic. For both, free EDTA and Co2+ compounds well-documented studies are available, which shows their toxicity. In general, the complex with the chelated Co2+ ion can be considered as less toxic than the free Co2+ ion due to retarded release. Based on that and that the complex EDTA-Co has an average stability, a worst-case assessment where the EDTA-CoH2 complex dissociate in its components can be done and so a read-across is possible to free EDTA and Co2+ salts.

Reason / purpose for cross-reference:

read-across source

Principles of method if other than guideline:

Induction of micronuclei (MN) in human leukocytes using the cytokinesis block method. Cells were treated for 15 minutes in the absence of metabolic activation starting 24 hr after PHA (phytohaemagglutinin) stimulation. Cells were harvested for the MN test after a total of 72 hr in culture.

GLP compliance:

not specified

Type of assay:

in vitro mammalian cell micronucleus test

Specific details on test material used for the study:

99.87% purity
median particle size (d50): 4 µm

Species / strain / cell type:

other: Leukocytes

Details on mammalian cell type (if applicable):

human volunteer age <= 30 years, healthy status
24h PHA stimulation (2%) prior to exposure
culture medium: Ham's F10 containing 15% foetal calf serum (FCS)

Additional strain / cell type characteristics:

not specified

Metabolic activation:

without

Test concentrations with justification for top dose:

0.6, 1.2, 3.0 and 6.0 µg/mL

Vehicle / solvent:

water (10 µL)

Positive controls:

yes

Positive control substance:

mitomycin C

Key result

Species / strain:

other: Leukocytes

Metabolic activation:

without

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

not specified

Untreated negative controls validity:

not specified

Positive controls validity:

not specified

Conclusions:

The result was positive for the test substance extra fine cobalt metal powder. Although the treatment time was short, and cells were not in exponential growth at the time of treatment, this is a reasonably robust study by current standards. A significant induction (>2-fold) in MN frequency at concentrations from 0.6 µg/ml and higher could be observed.

Reference 7

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

Justification for type of information:

The study is well-documented by the publication and thus acceptable for assessment.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Principles of method if other than guideline:

A total of 63 chemicals were tested for mutagenicity in a four-laboratory study (Inveresk Research International; Litton Bionetics, Inc.; New York Medical College and SRI International).

GLP compliance:

not specified

Type of assay:

bacterial reverse mutation assay

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Remarks:

and TA1538

Species / strain / cell type:

E. coli WP2 uvr A

Metabolic activation:

with and without

Metabolic activation system:

uninduced and Aroclor 1254-induced liver S9 mix of male Fischer 344 rats, B6C3F1 mice, and Syrian hamsters

Test concentrations with justification for top dose:

0.3; 1; 3; 10; 33; 100; 333; 1000; 3333; 10000 µg/plate

Vehicle / solvent:

dest. water

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

9-aminoacridine

2-nitrofluorene

sodium azide

other: 2-aminoanthracene; N-methyl-N'-nitro-N-nitrosoguanidine; 2-2(furyl)-3-(5-nitro-2-furyl)acrylamide

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 1538

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Conclusions:

A total of 63 chemicals were tested for mutagenicity in Salmonella typhimurium strains TA98, TA100, TA1535, TA1537, and TA1538, and Escherichia coli WP2 uvrA. The results for the test material trisodium hydrogen ethylenediaminetetraacetate was negative and so the test material was judged nonmutagenic.

Reference 8

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Justification for type of information:

The complex EDTA-CoH2 consist of the organic moiety EDTA, the central atom Co2+ and the hydrogen ions. As the latter are known to be non-toxic only the EDTA-Co complex must be regarded as toxic. For both, free EDTA and Co2+ compounds well-documented studies are available, which shows their toxicity. In general, the complex with the chelated Co2+ ion can be considered as less toxic than the free Co2+ ion due to retarded release. Based on that and that the complex EDTA-Co has an average stability, a worst-case assessment where the EDTA-CoH2 complex dissociate in its components can be done and so a read-across is possible to free EDTA and Co2+ salts.

Reason / purpose for cross-reference:

read-across source

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Principles of method if other than guideline:

A total of 63 chemicals were tested for mutagenicity in a four-laboratory study (Inveresk Research International; Litton Bionetics, Inc.; New York Medical College and SRI International).

GLP compliance:

not specified

Type of assay:

bacterial reverse mutation assay

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Remarks:

and TA1538

Species / strain / cell type:

E. coli WP2 uvr A

Metabolic activation:

with and without

Metabolic activation system:

uninduced and Aroclor 1254-induced liver S9 mix of male Fischer 344 rats, B6C3F1 mice, and Syrian hamsters

Test concentrations with justification for top dose:

0.3; 1; 3; 10; 33; 100; 333; 1000; 3333; 10000 µg/plate

Vehicle / solvent:

dest. water

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

9-aminoacridine

2-nitrofluorene

sodium azide

other: 2-aminoanthracene; N-methyl-N'-nitro-N-nitrosoguanidine; 2-2(furyl)-3-(5-nitro-2-furyl)acrylamide

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 1538

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Conclusions:

A total of 63 chemicals were tested for mutagenicity in Salmonella typhimurium strains TA98, TA100, TA1535, TA1537, and TA1538, and Escherichia coli WP2 uvrA. The results for the test material trisodium hydrogen ethylenediaminetetraacetate was negative and so the test material was judged nonmutagenic.

Reference 9

Endpoint:

genetic toxicity in vitro, other

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Justification for type of information:

Concise International Chemical Assessment Documents (CICAD) are published by the International Programme on Chemical Safety (IPCS) — a cooperative programme of the World Health Organization (WHO), the International Labour Organization (ILO), and the United Nations Environment Programme (UNEP).
The CICAD on cobalt and inorganic cobalt compounds was prepared by Sciences International, Inc. in the United States and the Centre for Ecology and Hydrology in the United Kingdom and was based on reviews prepared by the Agency for Toxic Substances and Disease Registry (ATSDR, 2004) and the International Agency for Research on Cancer (IARC, 2005). Consequently, this CICAD includes important information about the genetic toxicity of cobalt and inorganic cobalt compounds.

Principles of method if other than guideline:

The CICAD includes series experimental studies about the genetic toxicity of cobalt and inorganic cobalt compounds in mammalian and bacterial test systems. The used studies are well documented, meets generally accepted scientific principles and are acceptable for assessment.

GLP compliance:

not specified

Type of assay:

other: various

Key result

Species / strain:

other: Salmonella typhimurium, Escherichia coli, Bacillus subtilis, S. cerevisiae, human lymphocytes, hamster cells, mouse bone marrow cells, rat type II epithelial lung cells, human peripheral blood mononucleated cells

Metabolic activation:

with and without

Genotoxicity:

other: positive and negative

Cytotoxicity / choice of top concentrations:

other: positive and negative

Conclusions:

Many cobalt compounds are genotoxic in mammals and in mammalian and bacterial test systems. Cobalt(III) compounds are positive in bacterial test systems. Cobalt(II) compounds were positive for genetic conversions in Saccharomyces cerevisiae but otherwise demonstrated little genotoxic activity.

Executive summary:

There are no available studies on genotoxic effects in animals exposed by inhalation.

Cobalt, in compounds with a valence state of +2, was mostly negative in mutagenicity tests conducted in Salmonella typhimurium, Escherichia coli, and yeast, but weakly positive in Bacillus subtilis. The only positive report for cobalt(II) is from S. typhimurium TA100 both with and without liver S9 metabolic enzymes (NTP, 1998). S. typhimurium strains TA98 and TA1535 were negative. Cobalt(II) compounds caused genetic conversions in S. cerevisiae (Fukunaga et al., 1982; Singh, 1983; Kharab & Singh, 1985). The reasons for this dichotomy in yeast are unknown. Cobalt in compounds with a valence state of +3 was positive in S. typhimurium and E. coli (Schultz et al., 1982).

In mammalian test systems, many cobalt compounds and metals are genotoxic. Cobalt compounds and cobalt metals have been reported to cause clastogenic effects in mammalian cells such as human lymphocytes (Painter & Howard, 1982; Hamilton-Koch et al., 1986; Anard et al., 1997), transformation in hamster cells (Costa et al., 1982), sister chromatid exchanges in human lymphocytes (Andersen, 1983), and micronucleus formation in mouse bone marrow cells (Suzuki et al., 1993), human lymphocytes (Capomazza & Botta, 1991; Olivero et al., 1995; van Goethem et al., 1997), and rat type II epithelial lung cells (DeBoeck et al., 2003). Cobalt particles are genotoxic in vitro in human peripheral blood mononucleated cells (Anard et al., 1997; van Goethem et al., 1997; De Boeck et al., 1998, 2003).

In general, hard cobalt metal is more genotoxic than other cobalt compounds in in vitro test systems.

Cobalt toxicity is hypothesized to be the result of oxidant-based and free radical-based processes. Cobalt exposure affects genes that are sensitive to oxidant status, potentially leading to apoptosis. Soluble cobalt has also been shown to block inorganic calcium channels, which can affect neuromuscular transmissions. Cobalt is hypothesized to affect haem synthesis.

Reference 10

Endpoint:

genetic toxicity in vitro, other

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Justification for type of information:

The complex EDTA-CoH2 consist of the organic moiety EDTA, the central atom Co2+ and the hydrogen ions. As the latter are known to be non-toxic only the EDTA-Co complex must be regarded as toxic. For both, free EDTA and Co2+ compounds well-documented studies are available, which shows their toxicity. In general, the complex with the chelated Co2+ ion can be considered as less toxic than the free Co2+ ion due to retarded release. Based on that and that the complex EDTA-Co has an average stability, a worst-case assessment where the EDTA-CoH2 complex dissociate in its components can be done and so a read-across is possible to free EDTA and Co2+ salts.

Concise International Chemical Assessment Documents (CICAD) are published by the International Programme on Chemical Safety (IPCS) — a cooperative programme of the World Health Organization (WHO), the International Labour Organization (ILO), and the United Nations Environment Programme (UNEP).
The CICAD on cobalt and inorganic cobalt compounds was prepared by Sciences International, Inc. in the United States and the Centre for Ecology and Hydrology in the United Kingdom and was based on reviews prepared by the Agency for Toxic Substances and Disease Registry (ATSDR, 2004) and the International Agency for Research on Cancer (IARC, 2005). Consequently, this CICAD includes important information about the genetic toxicity of cobalt and inorganic cobalt compounds.

Reason / purpose for cross-reference:

read-across source

Principles of method if other than guideline:

The CICAD includes series experimental studies about the genetic toxicity of cobalt and inorganic cobalt compounds in mammalian and bacterial test systems. The used studies are well documented, meets generally accepted scientific principles and are acceptable for assessment.

GLP compliance:

not specified

Type of assay:

other: various

Key result

Species / strain:

other: Salmonella typhimurium, Escherichia coli, Bacillus subtilis, S. cerevisiae, human lymphocytes, hamster cells, mouse bone marrow cells, rat type II epithelial lung cells, human peripheral blood mononucleated cells

Metabolic activation:

with and without

Genotoxicity:

other: positive and negative

Cytotoxicity / choice of top concentrations:

other: positive and negative

Conclusions:

Many cobalt compounds are genotoxic in mammals and in mammalian and bacterial test systems. Cobalt(III) compounds are positive in bacterial test systems. Cobalt(II) compounds were positive for genetic conversions in Saccharomyces cerevisiae but otherwise demonstrated little genotoxic activity.

Executive summary:

There are no available studies on genotoxic effects in animals exposed by inhalation.

Cobalt, in compounds with a valence state of +2, was mostly negative in mutagenicity tests conducted in Salmonella typhimurium, Escherichia coli, and yeast, but weakly positive in Bacillus subtilis. The only positive report for cobalt(II) is from S. typhimurium TA100 both with and without liver S9 metabolic enzymes (NTP, 1998). S. typhimurium strains TA98 and TA1535 were negative. Cobalt(II) compounds caused genetic conversions in S. cerevisiae (Fukunaga et al., 1982; Singh, 1983; Kharab & Singh, 1985). The reasons for this dichotomy in yeast are unknown. Cobalt in compounds with a valence state of +3 was positive in S. typhimurium and E. coli (Schultz et al., 1982).

In mammalian test systems, many cobalt compounds and metals are genotoxic. Cobalt compounds and cobalt metals have been reported to cause clastogenic effects in mammalian cells such as human lymphocytes (Painter & Howard, 1982; Hamilton-Koch et al., 1986; Anard et al., 1997), transformation in hamster cells (Costa et al., 1982), sister chromatid exchanges in human lymphocytes (Andersen, 1983), and micronucleus formation in mouse bone marrow cells (Suzuki et al., 1993), human lymphocytes (Capomazza & Botta, 1991; Olivero et al., 1995; van Goethem et al., 1997), and rat type II epithelial lung cells (DeBoeck et al., 2003). Cobalt particles are genotoxic in vitro in human peripheral blood mononucleated cells (Anard et al., 1997; van Goethem et al., 1997; De Boeck et al., 1998, 2003).

In general, hard cobalt metal is more genotoxic than other cobalt compounds in in vitro test systems.

Cobalt toxicity is hypothesized to be the result of oxidant-based and free radical-based processes. Cobalt exposure affects genes that are sensitive to oxidant status, potentially leading to apoptosis. Soluble cobalt has also been shown to block inorganic calcium channels, which can affect neuromuscular transmissions. Cobalt is hypothesized to affect haem synthesis.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (positive)

Justification for classification or non-classification

The complex EDTA-CoH2 consist of the organic moiety EDTA, the central atom Co2+ and the hydrogen ions. As the latter are known to be non-toxic only the EDTA-Co complex must be regarded as toxic. For both, free EDTA and Co2+ compounds well-documented studies are available, which shows their toxicity. In general, the complex with the chelated Co2+ ion can be considered as less toxic than the free Co2+ ion due to retarded release. Based on that and that the complex EDTA-Co has an average stability, a worst-case assessment where the EDTA-CoH2 complex dissociate in its components can be done and so a read-across is possible to free EDTA and Co2+ salts.

The EDTA salt trisodium hydrogen ethylenediaminetetraacetate (Na3EDTA) was tested for mutagenicity in a four-laboratory study. The salt was tested for mutagenicity in Salmonella typhimurium strains TA98, TA100, TA1535, TA1537, and TA1538, and Escherichia coli WP2 uvrA. The results of all four laboratories was negative and so the test material was judged nonmutagenic. Therefore, special attention must be paid to the central atom cobalt of the EDTA complex.

Many cobalt compounds are genotoxic in mammals and in mammalian and bacterial test systems. Cobalt(II) compounds were positive for genetic conversions in Saccharomyces cerevisiae but otherwise demonstrated little genotoxic activity.

Cobalt, in compounds with a valence state of +2, was mostly negative in mutagenicity tests conducted in Salmonella typhimurium, Escherichia coli, and yeast, but weakly positive in Bacillus subtilis. The only positive report for cobalt(II) is from S. typhimurium TA100 both with and without liver S9 metabolic enzymes (NTP, 1998). S. typhimurium strains TA98 and TA1535 were negative. Cobalt(II) compounds caused genetic conversions in S. cerevisiae (Fukunaga et al., 1982; Singh, 1983; Kharab & Singh, 1985). The reasons for this dichotomy in yeast are unknown.

In mammalian test systems, many cobalt compounds and metals are genotoxic. Cobalt compounds and cobalt metals have been reported to cause clastogenic effects in mammalian cells such as human lymphocytes (Painter & Howard, 1982; Hamilton-Koch et al., 1986; Anard et al., 1997) or hamster embryo (SHE) cells (Gibson et al. 1997), transformation in hamster cells (Costa et al., 1982), sister chromatid exchanges in human lymphocytes (Andersen, 1983), and micronucleus formation in mouse bone marrow cells (Suzuki et al., 1993), human lymphocytes (Capomazza & Botta, 1991; Olivero et al., 1995; van Goethem et al., 1997), and rat type II epithelial lung cells (DeBoeck et al., 2003). Cobalt particles are genotoxic in vitro in human peripheral blood mononucleated cells (Anard et al., 1997; van Goethem et al., 1997; De Boeck et al., 1998, 2003).

In general, hard cobalt metal is more genotoxic than other cobalt compounds in in vitro test systems.

Cobalt toxicity is hypothesized to be the result of oxidant-based and free radical-based processes. Cobalt exposure affects genes that are sensitive to oxidant status, potentially leading to apoptosis. Soluble cobalt has also been shown to block inorganic calcium channels, which can affect neuromuscular transmissions. Cobalt is hypothesized to affect haem synthesis.

To summarize, the genetic toxicity of the EDTA-CoH2 complex strongly depends on the availability of the free cobalt ion. EDTA-Co complexes are known to be more stable (stability constant K=10^18.1; Environ. Sci. Technol. 2000, 34, 1715-1720) and so the genetic toxicity of the EDTA-Co complex can be stated to be minor. As there are still reasons for concern the substance

EDTA-CoH2

will be classified as germ cell mutagenicity 2.