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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
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:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
GLP compliance:
no
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
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 / strainopen allclose all
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Species / strain / cell type:
other: TA100NR
Remarks:
nitroreductase-deficient
Species / strain / cell type:
E. coli WP2 uvr A
Species / strain / cell type:
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 resultsopen allclose all
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
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
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
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
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
Key result
Species / strain:
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
Key result
Species / strain:
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

42t

99

-

-

-

-

17t

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.