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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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1998

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Qualifier:
according to
Guideline:
OECD Guideline 472 (Genetic Toxicology: Escherichia coli, Reverse Mutation Assay)
Qualifier:
according to
Guideline:
JAPAN: Guidelines for Screening Mutagenicity Testing Of Chemicals
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Supplier: Mitsubishi Gas Chem. Co., Inc.
Batch No.: NG60912
Purity: 99.6 %
Storage Conditions: Cool and dark location

Method

Target gene:
Histidine operon
Species / strainopen allclose all
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
Metabolic activation system:
S9: Rat liver, induced with phenobarbital and 5,6-benzoflavone 
Test concentrations with justification for top dose:
-S9 mix: 9.77, 19.5, 39.1, 78.1, 156, 313 and 625 µg/plate
+S9 mix: 9.77, 19.5, 39.1, 78.1, 156, 313, 625 and 1250 µg/plate
Vehicle / solvent:
DMSO
Controls
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: -S9 mix; 2-(2-Furyl)-3-(5-nitro-2-furyl) acrylamide (TA100, TA98, WP2 uvrA), Sodium azide (TA1535), 9-Aminoacridine (TA1537)  +S9 mix; 2-Aminoanthracene(all strains) 
Details on test system and experimental conditions:
100μl of the solvent used, the test substance solution and the positive control substance was placed in a capped tube, and then 500μl of 0.1M sodium phosphate buffer (pH7.4) for the direct method, or 500μl of the S9 mix for the metabolic activation method was added. Next, after adding 100μl of the pre-incubated test bacteria strain suspension, this was subject to 20 minutes of shaking incubation (pre-incubation) at 37°C using an incubator shaker. After incubation was completed, 2ml of top agar was added and the contents mixed. Then, the mixed solution was poured and evenly spread on the plate. After the layered top agar solidified, each plate was sealed with cellophane tape and incubated for 48 hours under conditions of 37°C using an incubator.
Three plates per dose were used. Also, to verify reproducibility, these tests were independently performed two times.
Evaluation criteria:
The number of reverse mutated colonies increased to nearly double that of the control solvent, and when the reproducibility and the test substance dose dependence was confirmed, it was deemed positive
Statistics:
A statistical analysis was not performed

Results and discussion

Test results
Species / strain:
other: Salmonella typhimurium TA100, TA1535, TA98, TA1537, Escherichia coli WP2 uvrA
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
>= 156 µg/plate in the 5 strains without S9. >=313 µg/plate (TA100, Ta1535, TA98, TA1537) and >= 625 µg/plate (WP2 uvrA) with S9
Vehicle controls validity:
valid
Untreated negative controls validity:
not examined
Positive controls validity:
valid
Additional information on results:
This chemical was not mutagenic in Salmonella typhimurium TA100, TA1535, TA98, TA1537 and Escherichia coli WP2 uvrA, with or without an exogenous metabolic activation system. 
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
negative

In a valid guideline study the test substance was not mutagenic in Salmonella typhimurium TA100, TA1535, TA98, TA1537 and Escherichia coli WP2 uvrA, with or without an exogenous metabolic activation system. 
Executive summary:

The potential of n-butyl methacrylate to induce reverse mutation in Salmonella typhimurium (strains: TA 1535, TA 1537, TA 98, and TA 100) and in Escherichia coli WP2 uvrA was evaluated in accordance with the international guidelines (OECD 471, Commission Directive No. B13/14) in compliance with the Principles of Good Laboratory Practice.

n-Butyl methacrylate was tested in two independent experiments, with and without a metabolic activation system, both performed according to preincubation method. Bacterias were exposed to the test item at 7 or 8 dose-levels (three plates/dose-level) selected from a preliminary toxicity test: 9.77, 19.5, 39.1, 78.1, 156, 313 and 625 µg/plate without S9 and 9.77, 19.5, 39.1, 78.1, 156, 313, 625 and 1250 µg/plate with S9. After 48 to 72 hours of incubation at 37°C, the revertant colonies were scored.

n-butyl methacrylate did not induce any noteworthy increase in the number of revertants, both with and without S9 mix, in any of the four Salmonella typhimurium strains and in Escherichia coli WP2 uvrA.

Under these experimental conditions, n-butyl methacrylate did not show any mutagenic activity in the bacterial reverse mutation test with Salmonella typhimurium and Escherichia coli.