Fenitrothion

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Not reported: published study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Data source

Reference

Reference Type:

publication

Title:

Mutagenicity studies on fenitrothion in bacteria and mammalian cells

Author:

Hara, M., Kogiso, S., Yamada, F., Kawamoto, M., Yoshitake, A., Miyamoto, J.

Year:

1989

Bibliographic source:

Mutation Research, 222, 53-61

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

GLP compliance:

no

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Fenitrothion

EC Number:

204-524-2

EC Name:

Fenitrothion

Cas Number:

122-14-5

Molecular formula:

C9H12NO5PS

IUPAC Name:

O,O-dimethyl O-3-methyl-4-nitrophenyl phosphorothioate

Test material form:

liquid

Specific details on test material used for the study:

Fenitrothion technical grade
Batch No.: 00106
Purity: 94.7%

Method

Target gene:

Various; reversion to histidine and tryptophan independence

Species / strain

Species / strain 1

Species / strain / cell type:

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

Species / strain 2

Species / strain / cell type:

S. typhimurium, other: TA100NR

Remarks:

nitroreductase-deficient

Species / strain 3

Species / strain / cell type:

E. coli WP2 uvr A

Species / strain 4

Species / strain / cell type:

S. typhimurium, other: TA100 1,8-DNP6

Remarks:

transacetylase deficient

Metabolic activation:

with and without

Metabolic activation system:

S9 from Sprague-Dawley rats treated intraperitoneally with polychlorinated biphenyls (PCB)

Test concentrations with justification for top dose:

0, 100, 200, 500, 1000, 2000, 5000 ug/plate (limit concentration)

Vehicle / solvent:

DMSO

Controls

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

no

Positive controls:

yes

Positive control substance:

9-aminoacridine

2-nitrofluorene

sodium azide

benzo(a)pyrene

methylmethanesulfonate

other: 2-aminoanthracene, 2, 80 ug/plate

Details on test system and experimental conditions:

Fenitrothion was tested using strains of Salmonella typhimurium (TA98, TA100, TA1535, TA1537, TA100 NR (nitroreductase-deficient strain) and TA100 1,8 -DNP6 (transacetylase-deficient strain)); and Escherichia coli WP2uvrA. Purified samples of fenitrothion and aminofenitrothion (AM-FNT) were tested using strains TA98, TA100, TA100 NR and TA100 1,8 -DNP6. Fenitrooxon (FNO), nitrosofenitrothion, nitrosofenitrooxon, aminofenitrooxon (AM-FNO) and 3-methyl-4-nitrophenol (NMC), were tested using strains TA98 and TA100. Test chemicals were dissolved in DMSO and tests were conducted using a pre-incubation method with and without metabolic activation. Negative control (DMSO, 100 ul /plate), positive and insensitive controls were also tested with and without metabolic activation. S9 mix, a mixture of cofactors and the liver S9 from Sprague-Dawley rats treated intraperitoneally with polychlorinated biphenyls (PCB), were used for metabolic activation.

Statistics:

Not required

Results and discussion

Test results

Test results 1

Key result

Species / strain:

S. typhimurium TA 98

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

Test results 2

Key result

Species / strain:

S. typhimurium TA 1535

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

Test results 3

Key result

Species / strain:

S. typhimurium TA 1537

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

Test results 4

Key result

Species / strain:

S. typhimurium TA 100

Remarks:

weak mutagenicity was observed only in TA100 and it was enhanced by the addition of S9 mix

Metabolic activation:

with and without

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Test results 5

Key result

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Test results 6

Key result

Species / strain:

S. typhimurium, other: TA100NR

Remarks:

nitroreductase deficient

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

Test results 7

Key result

Species / strain:

S. typhimurium, other: TA100 1,8-DNP6

Remarks:

transacetylase deficient strain

Metabolic activation:

with and without

Genotoxicity:

positive

Remarks:

Decreased compared to TA100

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

Fenitrothion showed weak mutagenicity in TA100 without S9 and its mutagenicity was slightly enhanced by the addition of S9. The mutagenic activity of the technical-grade sample of fenitrothion did not differ from that of the purified sample. The mutagenicity of fenitrothion was not detected in TA100 NR, and was decreased in TA100 1,8-DNP6.

Any other information on results incl. tables

Summary of results

Chemical	Dose (mg/plate)	Revertant colonies/plate
		Salmonella typhimurium
		TA100		TA100 NR		TA100 1,8-DNP6
		-S9	+S9	-S9	+S9	-S9	+S9
Fenitrothion (technical)	0	94	87	114	100	108	105
	100	113	122	107	104	126	120
	200	138	173	101	111	127	131
	500	192	323	110	105	141	145
	1000	203t	380	105t	104	152t	160
	2000	173t	315t	97t	103	154t	184
	5000	142t	173t	90t	101	174t	215
Fenitrothion (purified)	0	81	79	87	83	96	89
	100	116	121	81	93	104	104
	200	153t	164	88	96	113t	112
	500	224t	341	102	105	125t	128
	1000	224t	388t	89t	82	123t	141
	2000	222t	463t	86t	89	135t	146
	5000	221t	255t	80t	91	134t	154
MMS	100	413	-	468	-	514	-
B(a)P	5	-	827	-	949	-	964
2NF	2	485	-	154	-	176	-
1,8-DNP	0.01	473	-	771	-	151	-

t: evidence of toxicity

Chemical	Dose (mg/ plate)	Revertant colonies/plate
		Salmonella typhimurium						Escherichia coli
		TA98		TA1535		TA1537		WP2uvrA
		-S9	+S9	-S9	+S9	-S9	+S9	-S9	+S9
Fenitrothion (technical)	0	37	38	10	10	11	21	16	15
	100	32	36	9	10	8	14	19	21
	200	34	38	8	14	10	17	18	25
	500	34	44	9	15	5	12	25	20
	1000	31	40	7	13	4t	4t	24	22
	2000	26	37	9	9	3t	3t	22	21
	5000	21	39	7	8	3t	3t	23	25
Fenitrothion (purified)	0	25	44	-	-	-	-	-	-
	100	28	32	-	-	-	-	-	-
	200	30	35	-	-	-	-	-	-
	500	25	44	-	-	-	-	-	-
	1000	35t	42	-	-	-	-	-	-
	2000	22t	37	-	-	-	-	-	-
	5000	22t	37	-	-	-	-	-	-
2NF	1	355	-	-	-	-	-	-	-
	2	-	-	-	-	-	-	250
B(a)P	5	-	687	-	-	-	160	-	-
Sodium azide	0.5	-	-	341	-	-	-	-	-
2AA	2	-	-	-	141	-	-	-	-
	80	-	-	-	-	-	-	-	479
9AA	80	-	-	-	-	1474	-	-	-

t: evidence of toxicity

Chemical	Dose (mg/plate)	Revertant colonies/plate
		Salmonella typhimurium
		TA100		TA100NR		TA100 1,8-DNP6		TA98
		-S9	+S9	-S9	+S9	-S9	+S9	-S9	+S9
FNO	0	71	66	-	-	-	-	23	34
	3	71	69	-	-	-	-	31	39
	10	78	63	-	-	-	-	25	41
	30	83	69	-	-	-	-	24	36
	100	83	72	-	-	-	-	20	40
	300	91	101	-	-	-	-	36	49
	1000	165	204	-	-	-	-	33	43
Nitroso- fenitrothion	0	93	89	-	-	-	-	26	40
	2	106	86	-	-	-	-	38	40
	5	133	86	-	-	-	-	32	44
	10	118t	92	-	-	-	-	4t	38
	20	73t	113	-	-	-	-	Tox	53
	50	Tox	111	-	-	-	-	-	56
	100	-	103	-	-	-	-	-	59
	200	-	117	-	-	-	-	-	58
	500	-	Tox	-	-	-	-	-	151
Nitroso- fenitrooxon	0	71	66	-	-	-	-	23	34
	3	82	57	-	-	-	-	38	38
	10	90	72	-	-	-	-	29	42
	30	42^t	99	-	-	-	-	17^t	40
	100	Tox	106	-	-	-	-	Tox	49
	300	-	97	-	-	-	-	-	48
	1000	-	Tox	-	-	-	-	-	Tox
AM-FNT	0	83	64	104	97	132	112	30	46
	2	86	85	104	115	126	121	-	-
	5	96	118	109	145	124	137	-	-
	10	92	158	102	189	131	161	-	-
	20	78	225	110	244	119	181	-	-
	50	79	294	118	304	115	216	-	-
	100	88	355	113	332	119	205	32	65
	200	-	-	-	-	-	-	25	76
	500	38t	344	94t	373	123t	220	29	69
	1000	Tox	285t	Tox	393	89t	261	15t	58
	5000	-	-	-	-	-	-	Tox	Tox
AM-FNO	0	71	66	-	-	-	-	23	34
	3	77	63	-	-	-	-	37	46
	10	64	60	-	-	-	-	35	41
	30	70	64	-	-	-	-	26	38
	100	61	115	-	-	-	-	26	37
	300	83	221	-	-	-	-	25	63
	1000	96	290	-	-	-	-	34	60
NMC	0	94	100	-	-	-	-	27	49
	50	85	103	-	-	-	-	31	49
	100	88	92	-	-	-	-	24	42
	200	86	47	-	-	-	-	31	40
	500	100	61	-	-	-	-	27	35
	1000	45	38	-	-	-	-	12	26
	2000	Tox	Tox	-	-	-	-	Tox	3

t: evidence of toxicity

Tox: excessive toxicity, not scored

Applicant's summary and conclusion

Conclusions:

Fenitrothion was found to be non-mutagenic in TA98, TA1535, TA1537 and WP2uvrA both with and without S9 mix, while weak mutagenicity was observed only in TA100 and it was enhanced by the addition of S9 mix. The mutagenicity was not observed in a nitroreductase-deficient strain, TA100 NR, and it decreased in a transacetylase-deficient strain, TA100 1,8-DNP6. The results suggest that the bacterial nitroreductase activity is necessary for fenitrothion to express the mutagenicity in TA100.

Executive summary:

The mutagenic potenitial of fenitrothion was investigated in an Ames test. Fenitrothion was tested using strains of Salmonella typhimurium (TA98, TA100, TA1535, TA1537, TA100 NR (nitroreductase-deficient strain) and TA100 1,8 -DNP6 (transacetylase-deficient strain)); and Escherichia coli WP2uvrA. Purified samples of fenitrothion and aminofenitrothion (AM-FNT) were tested using strains TA98, TA100, TA100 NR and TA100 1,8 -DNP6. Fenitrooxon (FNO), nitrosofenitrothion, nitrosofenitrooxon, aminofenitrooxon (AM-FNO) and 3-methyl-4-nitrophenol (NMC), were tested using strains TA98 and TA100. Test chemicals were dissolved in DMSO and tests were conducted using a pre-incubation method with and without metabolic activation. Negative control (DMSO, 100 ul /plate), positive and insensitive controls were also tested with and without metabolic activation. S9 mix, a mixture of cofactors and the liver S9 from Sprague-Dawley rats treated intraperitoneally with polychlorinated biphenyls (PCB), were used for metabolic activation. Fenitrothion was found to be non-mutagenic in TA98, TA1535, TA1537 and WP2uvrA both with and without S9 mix, while weak mutagenicity was observed only in TA100 and it was enhanced by the addition of S9 mix. The mutagenicity was not observed in a nitroreductase-deficient strain, TA100 NR, and it decreased in a transacetylase-deficient strain, TA100 1,8-DNP6. The results suggest that the bacterial nitroreductase activity is necessary for fenitrothion to express the mutagenicity in TA100.