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Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1986
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study without detailed documentation

Data source

Reference
Reference Type:
publication
Title:
Salmonella mutagenicity tests: II. Results from the testing of 270 chemicals.
Author:
Mortelmans, K; Haworth, S; Lawlor, T; et al.
Year:
1986
Bibliographic source:
Environ Mutagen 8(7):1−119.

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
GLP compliance:
not specified
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: crystalline
Specific details on test material used for the study:
Zirconium oxychloride hexahydrate, obtained from Fluka Chemical Co, Technical Grade material.

Method

Species / strain
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Metabolic activation:
with and without
Metabolic activation system:
Aroclor 1254-induced rat and hamster metabolic activation systems
Test concentrations with justification for top dose:
Up to 1000 µg/plate. It is noted that this is not as high as normally expected
Vehicle / solvent:
Distilled water
Controlsopen allclose all
Untreated negative controls:
yes
Remarks:
Potassium chloride
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
9-aminoacridine
sodium azide
other: 4-nitro-o-phenylenediamine
Positive controls:
yes
Positive control substance:
other: 2-aminoanthracene
Details on test system and experimental conditions:
Tests were carried out as part of a programme of testing by the US NTP.

All chemicals were assayed for mutagenicity in the preincubation assay:
- To each of 13 X 100-mm test tubes maintained at 37°C were
added 0.5 ml of S-9 mix or 0.1 M PO4 buffer (pH 7.4), 0.05 ml of the overnight culture, and 0.05 ml of solvent or chemical dilution.
- The mixture was mixed and allowed to incubate without shaking at 37°C for 20 min, at which time 2.5 ml (EGG) or 2.0 ml (CWR, SFU) of molten (45°C) top agar supplemented with 0.5 mM L-histidine and 0.5 mM D-biotin were added.
- The contents of the tubes were mixed and poured onto 25 ml of minimal glucose bottom agar in 15 X 100-mm plastic petri dishes. When the top agar had solidified, the plates were inverted and incubated at 37°C for 48 hr.
- Concurrent solvent and positive controls were tested with and without the metabolic activation systems. At least five dose levels of the chemicals were tested, with three plates per dose level. All assays were repeated (as described above) no less than 1 wk after completion of the initial test.


Preliminary Dose-Setting Experiment
- All chemicals were initially tested with strain TA100 in the presence and the absence of the metabolic activation systems, over a wide dose range with an upper limit of 10 ug/plate.
Evaluation criteria:
The criteria used for data evaluation were those described previously in [Haworth et al, 1983], and are summarized as follows:
1) mutagenic response: a dose-related, reproducible increase in the number of revertants over background, even if the increase was less than twofold;
2) no mutagenic response: when no increase in the number of revertants was elicited by the chemical;
3) questionable response: when there was an absence of a clear-cut dose-related increase in revertants; when the dose-related increases in the number of revertants were not reproducible; or when the response was of insufficient magnitude to support a determination of mutagenicity

Results and discussion

Test resultsopen allclose all
Species / strain:
S. typhimurium TA 97
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
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
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
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
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

Applicant's summary and conclusion

Conclusions:
Zirconium oxychloride hexahydrate was negative for mutagenicity in Salmonella typhimrium strains TA1535, TA1537, TA98, and TAl00 with and without Aroclor 1254-induced rat and hamster metabolic activation systems.
Executive summary:

Zirconium oxychloride hexahydrate was tested for mutagenicity as part of a programme of testing for the US NTP in Salmonella typhimrium strains TA1535, TA1537, TA98, and TAl00 with and without Aroclor 1254-induced rat and hamster metabolic activation systems. The test results were negative for all strains tested with this substance.