Bis(pentane-2,4-dionato-O,O')zinc

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Three in vitro studies were performed:

A study according to OECD 487 gave an equivocal result. The test item induced weak but statistically significant increases in the frequency of cells with micronuclei in both the absence and presence of a metabolising system at dose levels which achieved less than optimum toxicity. Due to the relatively weak responses the test item cannot conclusively be considered to be clastogenic and aneugenic to human lymphocytes in vitro but conversely the indications of a response at dose levels which achieved less than optimum toxicity cannot be ignored.

In the study according to OECD 476 the test item did not induce any toxicologically significant dose-related increases in the mutant frequency at any dose levels exhibiting acceptable levels of toxicity, either with or without metabolic activation.

In the study according to OECD 471 no significant increases in the frequency of revertant colonies were recorded for any of the bacterial strains, with any dose of the test item, either with or without metabolic activation or exposure method.

It can be concluded that bis(pentane-2,4-dionato-O,O')zinc is not genetic toxic based on two unambiguously test. The results of the study according to OECD 487 are considered not to be evidence enough for a classification.

Link to relevant study records

Reference

Reference 1

Endpoint:

in vitro cytogenicity / micronucleus study

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 487 (In vitro Mammalian Cell Micronucleus Test)

GLP compliance:

yes (incl. QA statement)

Type of assay:

in vitro mammalian cell micronucleus test

Species / strain / cell type:

human lymphoblastoid cells (TK6)

Details on mammalian cell type (if applicable):

For each experiment, sufficient whole blood was drawn from the peripheral circulation of a volunteer who had been previously screened for suitability.

Metabolic activation:

with and without

Test concentrations with justification for top dose:

The dose levels used in the main experiments were selected using data from the preliminary toxicity test and were as follows:
- 4-hour without S9: 10,20,40, 50,60, 80 µg/mL
- 4-hour with S9 (2%): 20,40, 80, 100, 120, 160 µg/mL
- 20-hour without S9: 10,20,40,50,60,80 µg/mL
- 4-hour with S9 (1 %): 20,40,80, 100, 120, 160 µg/mL

Untreated negative controls:

yes

Negative solvent / vehicle controls:

no

True negative controls:

no

Positive controls:

yes

Positive control substance:

cyclophosphamide

mitomycin C

other: demecolcine

Details on test system and experimental conditions:

Duplicate cultures of human lymphocytes, treated with the test item, were evaluated for micronuclei in binucleate cells at up to four dose levels, together with vehicle and positive controls. Four exposure conditions were used for the study. Experiment 1 used a 4 hour exposure in the presence and absence of a standard metabolising system (S9, at a 2% final concentration). Experiment 2, used a repetition of the 4 hour exposure with S9 (at a 1 % final concentration), whilst in the absence of metabolic activation the exposure time was increased to 20 hours.

Statistics:

The frequency of cells with micronuclei was compared, where necessary, with the concurrent vehicle control value using the Chi-squared Test on observed numbers of cells with micronuclei.

Key result

Species / strain:

human lymphoblastoid cells (TK6)

Metabolic activation:

with and without

Genotoxicity:

ambiguous

Cytotoxicity / choice of top concentrations:

not determined

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Conclusions:

The test item induced weak but statistically significant increases in the frequency of cells with micronuclei in both the absence and presence of a metabolising system at dose levels which achieved less than optimum toxicity. Due to the relatively weak responses the test item cannot conclusively be considered to be clastogenic and aneugenic to human lymphocytes in vitro but conversely the indications of a response at dose levels which achieved less than optimum toxicity cannot be ignored and therefore an equivocal result has to be given.

Reference 2

Endpoint:

in vitro gene mutation study in mammalian cells

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Qualifier:

according to guideline

Guideline:

EU Method B.17 (Mutagenicity - In Vitro Mammalian Cell Gene Mutation Test)

GLP compliance:

yes (incl. QA statement)

Type of assay:

in vitro mammalian cell micronucleus test

Species / strain / cell type:

mouse lymphoma L5178Y cells

Additional strain / cell type characteristics:

not specified

Metabolic activation:

with and without

Test concentrations with justification for top dose:

The molecular weight of the test item was 263.59, therefore the maximum proposed dose level for the solubility test was initially set at 2636 μg/ml which was approximately equivalent to 10 mM. However, this was reduced to 1318 μg/ml due to formulation difficulties.

Vehicle / solvent:

The test item was accurately weighed and formulated in dimethyl sulfoxide (DMSO) prior to serial dilutions being prepared.

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

ethylmethanesulphonate

Key result

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not determined

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Conclusions:

The test item did not induce any toxicologically significant increases in the mutant frequency at the TK +/- locus in L5178Y cells and is therefore considered to be non-mutagenic under the conditions of the test.

Executive summary:

The maximum dose levels used in the Mutagenicity Test were limited by test item-induced toxicity. Precipitate of test item was not observed at any of the dose levels in the Mutagenicity Test. The vehicle (solvent) controls had acceptable mutant frequency values that were within the normal range for the L5178Y cell line at the TK +/locus. The positive control items induced marked increases in the mutant frequency indicating the satisfactory performance of the test and of the activity of the metabolising system.

The test item did not induce any toxicologically significant dose-related increases in the mutant frequency at any dose levels exhibiting acceptable levels of toxicity, either with or without metabolic activation.

Reference 3

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Qualifier:

according to guideline

Guideline:

EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Species / strain / cell type:

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

Species / strain / cell type:

E. coli WP2 uvr A

Metabolic activation:

with and without

Test concentrations with justification for top dose:

The dose range was determined in a preliminary toxicity assay and was 50 to 5000 µg/plate in the first experiment.
The concentrations tested were 0, 0.15, 0.5, 1.5, 5, 15, 50, 150, 500, 1500 and 5000 µg/plate.

Vehicle / solvent:

dimethyl sulphoxide

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

4-nitroquinoline-N-oxide

9-aminoacridine

N-ethyl-N-nitro-N-nitrosoguanidine

benzo(a)pyrene

other: 2-aminoanthracene

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not determined

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

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 determined

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

not determined

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

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 determined

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

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 determined

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Conclusions:

The test item, bis(pentane-2,4-dionato-O,O')zinc was considered to be non-mutagenic under the conditions of this test.

Executive summary:

The test item caused no visible reduction in the growth of the bacterial background lawn at any dose level and was, therefore, tested up to the maximum recommended dose level of 5000 µg/plate. A test item precipitate (particulate in appearance) was observed at and above 1500 µg/plate, this observation did not prevent the scoring of revertant colonies.

No significant increases in the frequency of revertant colonies were recorded for any of the bacterial strains, with any dose of the test item, either with or without metabolic activation or exposure method.

All of the positive control chemicals used in the test induced marked increases in the frequency of revertant colonies thus confirming the activity of the 59-mix and the sensitivity of the bacterial strains.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)