Imidazo[5,1-f][1,2,4]triazin-4(1H)-one, 2-(2-ethoxyphenyl)-5-methyl-7-propyl-

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Salmonella/microsome test (Ames test; strains TA 98, TA 100, TA 102, TA 1535 and TA 1537 ): negative (+/- S9 mix)

Link to relevant study records

Reference

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Feb 2000

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.5100 - Bacterial Reverse Mutation Test (August 1998)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Target gene:

Histidine gene locus

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102

Additional strain / cell type characteristics:

not applicable

Metabolic activation:

with and without

Metabolic activation system:

Aroclor 1254 induced male rat liver S9 mix

Test concentrations with justification for top dose:

0, 50, 158, 500, 1581, 5000 µg/plate (first and repeat test)

Vehicle / solvent:

DMSO

Untreated negative controls:

yes

Negative solvent / vehicle controls:

no

Remarks:

No solvent control was used since sufficient evidence was available in the literature and from testing laboratory experience, indicating that the solvents used had no influence on the spontaneous mutant counts of the used strains.

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: sodium azide (only TA 1535), nitrofurantoin (only TA 100), 4-nitro-1,2-phenylene diamine (TA 1537 and TA 98), cumene hydroperoxide (only TA 102), 2-aminoanthracene.

Remarks:

The positive controls sodium azide, nitrofurantoin, 4-nitro-1,2-phenylene diamine and cumene hydroperoxide were only used without S9 mix; the positive control 2-aminoanthracene was only used with S9 mix.

Details on test system and experimental conditions:

METHOD: Standard plate test and preincubation test; each concentration including the controls was tested in triplicate.

Evaluation criteria:

A reproducible and dose-related increase in mutant counts of at least one strain is considered to be a positive result. For TA 1535, TA 1537, TA 100 and TA 98 this increase should be about twice that of negative controls. For TA 102 an increase of about 100 mutants should be reached. Otherwise, the result is evaluated as negative. However, these criteria may be overruled by good scientific judgment. In case of questionable results, investigations should continue, possibly with modifications, until a final evaluation is possible.

Statistics:

not specified

Species / strain:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

weak, strain-specific bacteriotoxic effect at 5000 µg/plate

Vehicle controls validity:

not applicable

Untreated negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Table 1: Summary of results from the Salmonella mutagenicity assay (first test) with Imidazotriazinon (mean values of revertants per plate)

Dose (µg per plate)	Without metabolic activation
	TA 1535	TA 100	TA 1537	TA 98	TA 102
0	8	49	8	15	140
50	10	51	5	16	144
158	5	56	6	17	132
500	6	55	6	12	119
1581	8	60	5	9	115
5000	7	53	4	9	88
Positive control	629	153	108	156	281
Dose ( µg per plate )	With metabolic activation (liver S9 mix)
	TA 1535	TA 100	TA 1537	TA 98	TA 102
0	9	72	10	27	211
50	7	114	10	23	215
158	8	107	6	24	225
500	8	72	8	21	194
1581	7	91	7	27	229
5000	6	98	6	23	194
Positive control	186	946	59	2269	820

Table 2: Summary of results from the Salmonella mutagenicity assay (repeat test) with Imidazotriazinon (mean values of revertants per plate)

Dose (µg per plate)	Without metabolic activation
	TA 1535	TA 100	TA 1537	TA 98	TA 102
0	9	61	8	16	223
50	11	75	7	15	219
158	10	77	6	16	210
500	7	64	7	16	185
1581	8	80	9	16	196
5000	6	77	-	14	138
Positive control	518	218	112	127	452
Dose ( µg per plate )	With metabolic activation (liver S9 mix)
	TA 1535	TA 100	TA 1537	TA 98	TA 102
0	8	75	8	31	299
50	9	92	8	22	315
158	8	101	10	28	301
500	8	92	9	20	265
1581	8	122	9	23	277
5000	9	116	-	23	199
Positive control	146	1386	181	1193	526

Doses up to and including 1581 µg per plate did not cause any bacteriotoxic effects. Total bacteria counts remained unchanged and no inhibition of growth was observed. At 5000 µg per plate, the substance had only a weak, strain-specific bacteriotoxic effect. Due to the weakness of this effect this dose could nevertheless be used for assessment purposes. Substance precipitation occurred at the dose 1581 µg per plate and above.

Evidence of mutagenic activity of Imidazotriazinon was not seen. No biologically relevant increase in the mutant count, in comparison with the negative controls, was observed.

The positive controls sodium azide, nitrofurantoin, 4-nitro-1,2-phenylene diamine, cumene hydroperoxide and 2-aminoanthracene had a marked mutagenic effect, as was seen by a biologically relevant increase in mutant colonies compared to the corresponding negative controls.

Conclusions:

Interpretation of results (migrated information):
negative

Executive summary:

The mutagenic potential of Imidazotriazinon was evaluated in a Salmonella/microsome test with the S. typhimurium strains TA 98, TA 100, TA 102, TA 1535 and TA 1537 in the presence and absence of S9 mix according to OECD TG 471. Evidence of mutagenic activity was not seen up to the maximum recommended dose level of 5000 µg/plate. No biologically relevant increase in the mutant count, in comparison with the negative controls, was observed. Based on this test, the test substance was considered to be non-mutagenic without and with S9 mix in the plate incorporation as well as in the preincubation modification of the Salmonella/microsome test.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Additional information

Additional information from genetic toxicity in vitro:

The mutagenic potential of Imidazotriazinon was evaluated in a Salmonella/microsome test with the S. typhimurium strains TA 98, TA 100, TA 102, TA 1535 and TA 1537 in the presence and absence of S9 mix according to OECD TG 471 (Herbold, 2000). Evidence of mutagenic activity was not seen up to the maximum recommended dose level of 5000 µg/plate. No biologically relevant increase in the mutant count, in comparison with the negative controls, was observed. Based on this test, the test substance was considered to be non-mutagenic without and with S9 mix in the plate incorporation as well as in the preincubation modification of the Salmonella/microsome test.

Justification for selection of genetic toxicity endpoint
Only one study available

Justification for classification or non-classification

Based on the study results a classification according to Directive 67/548/EEC or Regulation (EC) No. 1272/2008 (CLP) is not warranted.