2-ethoxy-N-hydroxybenzenecarboximidamide

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Salmonella/microsome test (Ames test): weakly positive with strain TA 1537 (+ S9 mix) and negative with strains TA 98, TA 100, TA 102 and TA 1535 (+/- 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 to March 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

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, +/-S9 mix, all strains)
0, 1000, 2000, 3000, 4000, 5000, 6000, 7000 µg/plate (repeat test, +S9 mix, TA 1537 only)

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, other: TA 1537

Metabolic activation:

with

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

weak, strain-specific bacteriotoxic effect at 7000 µg/plate

Vehicle controls validity:

not examined

Untreated negative controls validity:

valid

Positive controls validity:

valid

Species / strain:

S. typhimurium, other: TA 1537

Metabolic activation:

without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

weak, strain-specific bacteriotoxic effect at 7000 µg/plate

Vehicle controls validity:

not examined

Untreated negative controls validity:

valid

Positive controls validity:

valid

Species / strain:

S. typhimurium, other: TA 1535, TA 98, TA 100, TA 102

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Remarks:

no bacteriotoxic effect up to 5000 µg/plate

Vehicle controls validity:

not examined

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 Imidoxim (mean values of revertants per plate)

Dose (µg per plate)	Without metabolic activation
	TA 1535	TA 100	TA 1537	TA 98	TA 102
0	10	85	8	31	289
50	10	91	6	40	282
158	8	82	5	39	260
500	10	90	5	32	316
1581	13	71	9	33	303
5000	11	82	11	33	254
Positive control	836	202	98	159	409
Dose ( µg per plate )	With metabolic activation (liver S9 mix)
	TA 1535	TA 100	TA 1537	TA 98	TA 102
0	12	97	10	41	309
50	10	89	7	43	346
158	10	102	9	40	344
500	9	98	13	41	341
1581	11	106	13	47	354
5000	7	116	20	30	348
Positive control	293	1489	356	1570	920

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

Dose (µg per plate)	Without metabolic activation
	TA 1535	TA 100	TA 1537	TA 98	TA 102
0	10	63	9	18	230
50	8	65	8	20	237
158	12	64	8	19	241
500	11	64	10	22	249
1581	16	81	9	22	249
5000	13	79	14	15	193
Positive control	734	288	145	148	533
Dose (µg per plate)	With metabolic activation (liver S9 mix)
	TA 1535	TA 100	TA 1537	TA 98	TA 102
0	9	76	9	31	319
50	9	100	9	30	332
158	10	98	11	28	317
500	8	98	15	32	337
1581	10	91	19	30	326
5000	9	101	25	28	254
Positive control	259	1654	312	1734	659
0			9
1000			13
2000			16
3000			20
4000			28
5000			29
6000			28
7000			29
Positive control			235

Doses up to and including 6000 µg per plate did not cause any bacteriotoxic effects. Total bacteria counts remained unchanged and no inhibition of growth was observed. At 7000 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.

Evidence of mutagenic activity of Imidoxim was seen. Under both test conditions, a weak but biologically relevant increase was found in the mutant count of Salmonella typhimurium TA 1537 as compared to the corresponding negative control. Positive response was found only with S9 mix. The lowest reproducible dose was 3000 µg per plate. The Salmonella/microsome test thus showed Imidoxim to have a mutagenic effect. Due to the high amounts of Imidoxim need for a positive response, the positive result may be also due to an impurity.

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):
positive with metabolic activation

Executive summary:

The mutagenic potential of Imidoxim 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. Doses up to and including 6000 µg per plate did not cause any bacteriotoxic effects. Total bacteria counts remained unchanged and no inhibition of growth was observed. At 7000 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.

Evidence of mutagenic activity of Imidoxim was seen. Under both test conditions, a weak but biologically relevant increase was found in the mutant count of Salmonella typhimurium TA 1537 as compared to the corresponding negative control. Positive response was found only with S9 mix. The lowest reproducible dose was 3000 µg per plate. The Salmonella/microsome test thus showed Imidoxim to have a mutagenic effect. Due to the high amounts of Imidoxim need for a positive response, the positive result may be also due to an impurity.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (positive)

Genetic toxicity in vivo

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

The mutagenic potential of Imidoxim 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). Doses up to and including 6000 µg per plate did not cause any bacteriotoxic effects. Total bacteria counts remained unchanged and no inhibition of growth was observed. At 7000 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. Evidence of mutagenic activity of Imidoxim was seen. Under both test conditions, a weak but biologically relevant increase was found in the mutant count of Salmonella typhimurium TA 1537 as compared to the corresponding negative control. Positive response was found only with S9 mix. The lowest reproducible dose was 3000 µg per plate. The Salmonella/microsome test thus showed Imidoxim to have a mutagenic effect. Due to the high amounts of Imidoxim need for a positive response, the positive result may be also due to an impurity.

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.