Oct-7-enal

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Under the requirements of REACh Annex VII the genotoxicity assessment is restricted to an in vitro gene mutation study in bacteria.When tested in vitro, Oct-7-enal was negative in an Ames test.

It was concluded that Oct-7 -enal did not induce mutation in four histidine-requiring strains (TA98, TA100, TA1535 and TA1537) of Salmonella typhimurium, and one tryptophan-requiring strain (WP2uvrA) of Escherichia coli when tested under the conditions of this study. These conditions included treatments at concentrations up to 313 µg/mL (a concentration limited by toxicity), in the absence and presence of a rat liver metabolic activation system (S9) using pre-incubation methodology.

Link to relevant study records

Reference

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017-04-20 to 2017-04-24

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

1997

Deviations:

no

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Chemical name: Oct-7-enal (OEL)
- CAS no.: 21573-31-9
- EC-no.: not assigned
- Source and lot/batch No.of test material: Kuraray / 161110
- Expiration date of the lot/batch: not stated
- Molecular weight: 126.198 g/mol
- Purity: 94.2%

Target gene:

see below

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2

Additional strain / cell type characteristics:

not applicable

Cytokinesis block (if used):

n/a

Metabolic activation:

with and without

Metabolic activation system:

phenobarbital / 5,6-benzoflavone

Test concentrations with justification for top dose:

Dose range finder: -/+S9: 0, 19.5, 78.1, 313, 1250, 5000 ug/plate
Main study: -/+S9: 0, 9.77, 19.5, 39.1, 78.1, 156, 313 ug/plate

Vehicle / solvent:

DMSO

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-aminoanthracene

Remarks:

+S9: TA1535, WP2uvrA

Positive controls:

yes

Positive control substance:

benzo(a)pyrene

Remarks:

+S9: TA100, TA98, TA1537

Positive controls:

yes

Positive control substance:

furylfuramide

Remarks:

-S9: TA100, TA98, WP2uvrA

Positive controls:

yes

Positive control substance:

sodium azide

Remarks:

-S9: TA1535

Positive controls:

yes

Positive control substance:

other: ICR-191 (6-Chloro-9-[3-(2-chloroethylamino)propylamino]-2-methoxyacridine dihydrochloride)

Remarks:

-S9: TA1537

Details on test system and experimental conditions:

The pre-incubation methodology was used for the dose range finder and main tests 1 and 2. Duplicate plates were used for the dose range finder and triplicate plates were used for the main tests.

Test tubes containing 0.1 mL of vehicle, positive control or test article formulation were mixed with 0.5 mL S9 mix (or PBS in the absence of metabolic activation).. 0.1 mL fresh bacterial culture was added and the mixture was incubated while shaking at 37°C for 20 minutes.

After pre-incubation, 2 mL of top agar (kept at 45°C) was added to each tube and this mixture was shaken and overlaid onto Vogel-Bonner agar plates (minimal glucose agar plates). E.coli containing tubes were poured onto minimal agar plates.

Agar plates were incubated at 37°C for 48 h in the dark for the bacterial colonies (his+ or typ+ revertants) counted.

The background lawns of the plates were examined for signs of toxicity. Other toxicity indicators that may have been noted included a marked reduction in revertants compared to the concurrent vehicle controls and/or a reduction in mutagenic response.

Evaluation criteria:

The test chemical was considered positive in this assay if the following criteria were met:
- dose-related and reproducible increase in the number of revertant colonies (i.e. doubling of the spontaneous mutation rate in at least one tester strain either –S9 or +S9)

A test substance was generally considered non-mutagenic in this test if:
- The number of revertants for all tester strains were within the historical negative control range under all experimental conditions in two experiments carried out independently of each other.

Statistics:

Statistics not warranted

Key result

Species / strain:

other: S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2uvrA

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Remarks on result:

other: no mutagenic potential

A. Dose range finder:

No precipitation was observed at any dose level, - or + S9. Growth inhibition (evaluation by bacterial background lawn) was observed at 313 ug/plate and above for all strains in both the absence and presence of S9. Oct-7-enal was deemed not mutagenic in the dose range finder experiment following a pre-incubation methodology. For main mutation tests 1 and 2, as growth inhibition was the limiting factor the maximum dose level was set at 313 ug/plate for all strains.

 

Table 7.6.1/01-1: Bacterial (reverse) gene mutation pre-incubation data – Dose range finder

Conc. (ug/plate)	TA100		TA1535		WP2uvrA		TA98		TA1537
	-S9	+S9	-S9	+S9	-S9	+S9	-S9	+S9	-S9	+S9
0	93	97	8	8	23	29	16	30	8	7
19.5	101	126	7	8	22	22	12	23	5	5
78.1	102	93	5	6	21	24	13	26	5	9
313	0B	0B	0B	3B	2B	4B	2B	1B	1B	0B
1250	0B	0B	0B	0B	0B	0B	0B	0B	0B	0B
5000	0B	0B	0B	0B	0B	0B	0B	0B	0B	0B
+ve	541	1101	225	288	80	883	344	351	1289	115
B: reduced background lawn +ve controls: -S9 (absence of metabolic activation): TA100, WP2uvrA, TA98: furylfuramide TA1535: sodium azide TA1537: ICR-191					+S9 (presence of metabolic activation): TA100, TA98, TA1537: Benzo[a]pyrene TA1537, WP2urvA: 2-aminoanthracene

 

B. Main mutation tests

No precipitation was observed at any dose level. For main mutation tests 1 and 2, growth inhibition (evaluation by bacterial background lawn) was observed at 156 ug/plate and above for all strains in both the absence and presence of S9.

 

The positive controls induced an acceptable increase in revertant colony numbers, thereby demonstrating the sensitivity and specificity of the test system.

 

Following Oct-7-enal treatments of all the test strains in the absence and presence of S-9, no increases in revertant numbers were observed that were equal to or greater than 2-fold above the concurrent vehicle control in two independent experiments. This study was therefore considered to have provided no evidence of any mutagenic activity in this assay system (refer to Table 7.6.1/01-2, -3).

 

Table 7.6.1/01-2: Bacterial (reverse) gene mutation pre-incubation data – Main mutation experiment 1

Conc. (ug/plate)	TA100		TA1535		WP2uvrA		TA98		TA1537
	-S9	+S9	-S9	+S9	-S9	+S9	-S9	+S9	-S9	+S9
0	177	132	8	10	25	28	20	32	9	10
9.77	122	123	10	9	27	28	18	33	6	7
19.5	118	128	9	6	23	23	18	34	6	11
39.1	111	136	8	6	25	31	17	38	9	9
78.1	113	131	8	6	24	25	18	28	7	9
156	0B	125B	0B	5B	21B	27B	0B	0B	0B	7B
313	0B	14B	0B	0B	0B	0B	0B	0B	0B	0B
+ve	500	1146	235	294	83	870	372	368	1313	125
B: reduced background lawn +ve controls: -S9 (absence of metabolic activation): TA100, WP2uvrA, TA98: furylfuramide TA1535: sodium azide TA1537: ICR-191					+S9 (presence of metabolic activation): TA100, TA98, TA1537: Benzo[a]pyrene TA1537, WP2urvA: 2-aminoanthracene

 

Table 7.6.1/01-3: Bacterial (reverse) gene mutation pre-incubation data – Main mutation experiment 2

Conc. (ug/plate)	TA100		TA1535		WP2uvrA		TA98		TA1537
	-S9	+S9	-S9	+S9	-S9	+S9	-S9	+S9	-S9	+S9
0	120	114	10	10	25	25	18	33	8	7
9.77	107	114	7	7	28	19	18	25	10	5
19.5	95	118	7	8	27	23	16	26	8	6
39.1	104	110	8	7	27	25	19	27	9	6
78.1	129	112	7	5	27	27	18	28	10	8
156	76B	102B	0B	7B	24B	26B	0B	10*	1B	8B
313	0B	0B	0B	0B	8B	0B	0B	0*	0B	0B
+ve	483	873	234	308	86	936	379	399	1126	103
B: reduced background lawn +ve controls: -S9 (absence of metabolic activation): TA100, WP2uvrA, TA98: furylfuramide TA1535: sodium azide TA1537: ICR-191					+S9 (presence of metabolic activation): TA100, TA98, TA1537: Benzo[a]pyrene TA1537, WP2urvA: 2-aminoanthracene

 

Table 7.6.1/01-4: Bacterial (reverse) gene mutation data – Historical vehicle and positive control data

Conc. (ug/plate)	TA100		TA1535		WP2uvrA			TA98		TA1537
	-S9	+S9	-S9	+S9	-S9		+S9	-S9	+S9	-S9	+S9
Vehicle control
Mean ± SD	117 ± 13.7	132 ± 17.2	9 ± 2.6	10 ± 2.75	27 ± 3.98		30 ± 4.41	18 ± 3.50	32 ± 5.45	8 ± 2.36	10 ± 2.55
Lower limit	76	80	1	2	15		17	7	15	1	2
Upper limit	158	183	17	156	39		44	28	48	15	17
Positive control
Mean ± SD	547 ± 71.8	891 ± 126	233 ± 26.4	258 ± 34.1	71 ± 6.4		718 ± 114	348 ± 57.1	384 ± 48.4	1011 ± 193	110 ± 12.1
Lower limit	331	512	154	156	52		375	174	245	431	73
Upper limit	762	1269	312	360	91		1062	517	523	1590	146
-S9 (absence of metabolic activation): TA100, WP2uvrA, TA98: furylfuramide TA1535: sodium azide TA1537: ICR-191						+S9 (presence of metabolic activation): TA100, TA98, TA1537: Benzo[a]pyrene TA1537, WP2urvA: 2-aminoanthracene

C. Deficiencies:

None.

Conclusions:

It was concluded that Oct-7-enal did not induce mutation in four histidine-requiring strains (TA98, TA100, TA1535 and TA1537) of Salmonella typhimurium, and one tryptophan-requiring strain (WP2uvrA) of Escherichia coli when tested under the conditions of this study. These conditions included treatments at concentrations up to 313 µg/mL (a concentration limited by toxicity), in the absence and presence of a rat liver metabolic activation system (S9) using pre-incubation methodology.

Executive summary:

In a reverse gene mutation assay in bacteria, Salmonella typhimurium strains TA98, TA100, TA1535 and TA1537 and Escherichia coli strain WP2uvrA were exposed to Oct-7-enal formulated in dimethyl sulphoxide. The pre-incubation methodology was used. Following a dose range-finder experiment, two main mutation experiments were conducted using the same dose levels. For main mutation tests 1 and 2, s growth inhibition was the limiting factor the maximum dose level was set at 313 ug/plate for all strains in the absence and presence of S9. In the main mutation tests treatments of all the tester strains were performed in the absence and presence of S-9, using final concentrations of Oct-7-enal at 9.77, 19.5, 39.1, 78.1, 156, 313 µg/plate for all strains in the absence and presence of S9. No precipitation was observed at any dose level. For main mutation tests 1 and 2, growth inhibition (evaluation by bacterial background lawn) was observed at 156 ug/plate and above for all strains in both the absence and presence of S9. The positive controls induced an acceptable increase in revertant colony numbers, thereby demonstrating the sensitivity and specificity of the test system. Following Oct-7-enal treatments of all the test strains in the absence and presence of S-9, no increases in revertant numbers were observed that were equal to or greater than 2-fold above the concurrent vehicle control. This study was therefore considered to have provided no evidence of any mutagenic activity in this assay system under the conditions of this study. These conditions included treatments at concentrations up to 313 µg/mL (a concentration limited by toxicity), in the absence and presence of a rat liver metabolic activation system (S9) using pre-incubation methodology.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Description of key information

Under the requirements of REACh Annex VII the genotoxicity assessment is restricted to an in vitro gene mutation study in bacteria.

Endpoint conclusion

Endpoint conclusion:

no study available

Mode of Action Analysis / Human Relevance Framework

Under the requirements of REACh Annex VII the genotoxicity assessment is restricted to an in vitro gene mutation study in bacteria.When tested in vitro, Oct-7-enal was negative in an Ames test.

Justification for classification or non-classification

Comparison with the CLP criteria

There was no indication that Oct-7-enal has a mutagenic effect in the in vitro bacterial (reverse) gene mutation assay. Therefore, under the requirements of REACh Annex VII the criteria for classification for mutagenicity were not met and no classification is proposed.