Zirconium carbide

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

No data is available for Zirconium carbide (target substance). Thus, to assess the mutagenicity potential of Zirconium carbide available data from Zirconium oxychloride and Zirconium disilicide (source substances) were used in a read-across approach. In a bacterial reverse gene mutation assay with Zirconium oxychloride, the source substance was tested negative in S. typhimurium strains TA1535, TA1537, TA98 and TA100. In an OECD 471 study the source substance Zirconium disilicide was not soluble in a range of solvents for preparing the dilution series of the test material. Thus, it was not possible to conduct the study. Based on the low solubility of the target substance (see IUCLID section 4.8, 7.1.1) and the results obtained from the read-across partners, Zirconium carbide can be considered as not mutagenic and no further testing is required.

Link to relevant study records

Reference

Reference 1

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

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

Adequacy of study:

weight of evidence

Justification for type of information:

For justification of read-across please refer to the read-across report attached to IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Key result

Species / strain:

other: TA1535, TA1537, TA100 and TA98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity, but tested up to precipitating concentrations

Vehicle controls validity:

not examined

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

For detailed results please refer to table 1 in box "Any other information on results incl. tables"

Remarks on result:

other: non-mutagenic

Table 1: Summary of Results
Concentration  µg/plate		TA100						Concentration  µg/plate		TA1535
		without S9		with 10% hamster S9		with 10% rat S9				without S9				with 10% hamster S9				with 10% rat S9
		Mean	SEM	Mean	SEM	Mean	SEM			Mean	SEM	Mean	SEM	Mean	SEM	Mean	SEM	Mean	SEM	Mean	SEM
Negative Control		142	4.6	127	1	150	5.5	Negative Control		31	2.6	9	1.3	34	2.4	24	3.5	34	3.3	29	1.5
Positive Control		268	19.3	1572	41.5	742	48.2	Positive Control		344	6.9	175	23.2	505	12.5	326	15.2	223	19.9	114	6.1
10		-	-	-	-	-	-	10		28	5.2	-	-	36	2.3	-	-	45	5.8	-	-
33		-	-	-	-	-	-	33		29	3.5			36	3.2	-	-	39	2.2	-	-
100		125	8.2	158	9.5	136	4.5	100		30	2.4	22	3.0	41	3.5	33	2.3	42	6.6	30	1.0
333		108	10.9	169	10.5	126	7.1	333		30	1.0	29	6.4	38	6.1	37	3.1	35	3.7	33	3.6
1000		116	13.1	156	7.0	134	3.7	1000		30p	1.0	20	4.2	30p	0.3	35	4.9	38p	6.8	31	3.2
3333		149p	13.5	144p	14.0	77p	38.8	3333		-	-	26p	3.8	-	-	0p	0.0	-	-	29p	6.8
6666		48p	24.0	126p	5.2	35p	35.3	6666		-	-	0p	0.0	-	-	0p	0.0	-	-	0p	0.0

p= precipitation present in plates

Table 1 continued: Summary of Results
Concentration  µg/plate		TA1537						TA98
		without S9		with 10% hamster S9		with 10% rat S9		without S9		with 10% hamster S9		with 10% rat S9
		Mean	SEM	Mean	SEM	Mean	SEM	Mean	SEM	Mean	SEM	Mean	SEM
Negative Control		7	2.9	7	0.7	12	3.2	25	0.0	32	0.9	30	3.5
Positive Control		109	8.7	536	34.9	197	7.6	793	25.9	1385	100.5	556	36.2
10		-	-	-	-	-	-	-	-	-	-	-	-
33		-	-	-	-	-	-	-	-	-	-	-	-
100		8	0.9	13	4.2	7	1.2	21	4.3	34	2.7	30	0.6
333		8	1.9	8	1.9	9	2.6	28	1.5	34	2.6	32	4.2
1000		8	1.8	12	2.0	9	2.2	21	4.6	32	5.8	27	4.1
3333		9p	1.8	7p	2.5	13p	0.9	19p	1.5	30p	3.0	28p	2.2
6666		0p	0.0	0p	0.0	0p	0.0	0p	0.0	0p	0.0	0p	0.0

p= precipitation present in plates

Conclusions:

In conclusion, it can be stated that during the described mutagenicity test and under the experimental conditions reported, the test item can be considered as non-mutagenic.

Executive summary:

In a reverse gene mutation assay in bacteria conducted similar to OECD test guideline 471, strains TA98, TA100, TA1535 and TA1537 of Salmonella typhimurium were exposed to Zirconium oxychloride hexahydrate in 95% ethanol at concentrations of 10, 33, 100, 333, 1000, 3333 and 6666 µg/plate in the presence and absence of mammalian metabolic activation. The positive controls induced the appropriate responses in the corresponding strains. There was no evidence of induced mutant colonies over background in all tester strains. Therefore, Zirconium oxychloride hexahydrate is considered to be non-mutagenic in this Salmonella typhimurium reverse gene mutation assay.

 

This information is used in a read-across approach in the assessment of the target substance.

For justification of read-across please refer to the attached read-across report (see IUCLID section 13).

Reference 2

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

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

Adequacy of study:

weight of evidence

Justification for type of information:

For justification of read-across please refer to the read-across report attached to IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Species / strain:

S. typhimurium, other: TA 98, TA 100, TA 1535, TA 1537

Metabolic activation:

not applicable

Genotoxicity:

not determined

Cytotoxicity / choice of top concentrations:

not determined

Vehicle controls validity:

not examined

Untreated negative controls validity:

not examined

Positive controls validity:

not examined

Additional information on results:

The test item could not be prepared in an appropriate solvent and diluted prior to treatment. Due to the properties of the material, Zirconium disilicide was not soluble in any of the solvents used (A. dest, DMSO, ethanol and tetrahydrofuran). No stable suspension which is suitable for the preparation of the dilution series could be obtained. Therefore it was not possible to perform any further steps in this study.

Remarks on result:

not measured/tested

Conclusions:

Zirconium disilicide was not soluble in any of the solvents used. Therefore it was not possible to perform an Ames test.

Executive summary:

In this study, the test item Zirconium disilicide could not be prepared in an appropriate solvent and diluted prior to treatment. Due to the properties of the material, Zirconium disilicide was not soluble in any of the solvents used (A. dest, DMSO, ethanol and tetrahydrofuran). No stable suspension which is suitable for the preparation of the dilution series could be obtained. Therefore it was not possible to perform any further steps in this study. Since the test item could not be prepared in an appropriate solvent and diluted prior to treatment, it was not possible to perform an Ames test with Zirconium disilicide.

This information is used in a read-across approach in the assessment of the target substance.

For justification of read-across please refer to the attached read-across report (see IUCLID section 13).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Additional information

No data is available for Zirconium carbide (target substance). Thus, to assess the mutagenicity potential of Zirconium carbide available data from the source substances Zirconium oxychloride and Zirconium disilicide were used in a read-across approach. For justification of read-across please refer to the read-across report attached to IUCLID section 13.

In a bacterial reverse gene mutation assay with Zirconium oxychloride, the source substance was tested negative in S. typhimurium strains TA1535, TA1537, TA98 and TA100. In an OECD 471 study the second source substance Zirconium disilicide was not soluble in a range of solvents for preparing the dilution series of the test material. Thus, it was not possible to conduct the study.

Based on the low solubility of the target substance (see IUCLID section 4.8) and the results obtained from a bio-elution test (see IUCLID section 7.1.1) the bioavailability of zirconium, as the toxicological relevant part of the target substance, can be expected to be very low. Based on the data obtained from read-across partners together with the low solubility and bioavailabilty of the target substance, Zirconium carbide can be considered as not mutagenic.

Justification for classification or non-classification

Based on available data from a suitable read-across partner, the target substance Zirconium carbide does not warrant classification for mutagenicity.