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Toxicological information

Genetic toxicity: in vitro

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Administrative data

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:
2011-12-14 to 2012-01-09
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2012
Report Date:
2012

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 870.5100 - Bacterial Reverse Mutation Test (August 1998)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
Bayerisches Landesamt für Gesundheit und Lebensmittelsicherheit, München, Germany
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Name: Sodium methyl-4-hydroxybenzoate
CAS No.: 5026-62-0
Chemical Name: sodium 4-(methoxycarbonyl)phenolate
Physical State/Colour: solid/white
Storage Conditions: room temperature

Method

Target gene:
His
Species / strain
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102
Metabolic activation:
with and without
Metabolic activation system:
rat S9 liver microsomal fraction
Test concentrations with justification for top dose:
Experiment I (plate incorporation test):
31.6, 100, 316, 1000, 2500 and 5000 µg/plate
Experiment II (pre-incubation test):
10.0, 31.6, 100, 316, 1000, 2500 and 5000 µg/plate
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: A.dest.
Controls
Untreated negative controls:
yes
Remarks:
A. dest., BSL Lot No. 111102, 111125, 111201, 111219
Negative solvent / vehicle controls:
yes
Remarks:
A. dest., BSL Lot No. 111102, 111125, 111201, 111219
True negative controls:
no
Positive controls:
yes
Positive control substance:
other:
Remarks:
Positive control without metabolic activation: sodium azide for tester strains TA100, TA1535; 4-nitro-o-phenylene-diamine for TA98, TA1537; methylmethanesulfonate for TA102. Positive control with metabolic activation: 2-aminoanthracene for all strains
Details on test system and experimental conditions:
METHOD OF APPLICATION: in agar (plate incorporation); preincubation

DURATION
- Preincubation period: 60 min; 100 µL of the test item preparation was pre-incubated with the tester strains (100 µL) and sterile buffer or the metabolic activation system (500 µL) for 60 min at 37 °C prior to adding the overlay agar (2000 µL) and pouring onto the surface of a minimal agar plate.
- Exposure duration: at least 48 h; After solidification the plates were inverted and incubated at 37 °C for at least 48 h in the dark.


NUMBER OF REPLICATIONS: For each strain and dose level, including the controls, three plates per experiment were used.


DETERMINATION OF CYTOTOXICITY
- Method: clearing or rather diminution of the background lawn or a reduction in the number of revertants down to a mutation factor of approximately ≤ 0.5 in relation to the solvent control

Evaluation criteria:
The Mutation Factor is calculated by dividing the mean value of the revertant counts through the mean values of the solvent control (the exact and not the rounded values are used for calculation).
A test item is considered as mutagenic if:
- a clear and dose-related increase in the number of revertants occurs and/or
- a biologically relevant positive response for at least one of the dose groups occurs
in at least one tester strain with or without metabolic activation.
A biologically relevant increase is described as follows:
- if in tester strains TA 98, TA 100 and TA 102 the number of reversions is at least twice as high
- if in tester strains TA 1535 and TA 1537 the number of reversions is at least three times higher
than the reversion rate of the solvent control.
Statistics:
According to OECD guidelines, the biological relevance of the results is the criterion for the interpretation of results, a statistical evaluation of the results is not regarded as necessary.

Results and discussion

Test results
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
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
No precipitation of the test item was observed in any tester strain used in experiment I and II (with and without metabolic activation).
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Any other information on results incl. tables

Toxic effects of the test item were noted in all tester strains except tester strain TA 98 in experiment I and in all tester strains evaluated in experiment II.

In experiment I toxic effects of the test item were observed in tester strains TA 100, TA 1535 and TA 1537 at a concentration of 5000 µg/plate (without metabolic activation). In tester strain TA 102 toxic effects of the test item were noted at a concentration of 5000 µg/plate (with and without metabolic activation).

In experiment II toxic effects of the test item were noted in tester strains TA 98 and TA 102 at concentrations of 2500 µg/plate and higher (with and without metabolic activation). In tester strains TA 100, TA 1535 and TA 1537 toxic effects of the test item were noted at concentrations of 1000 µg/plate and higher (without metabolic activation) and at concentrations of 2500 µg/plate and higher (with metabolic activation). The reduction in the number of revertants down to a mutation factor of 0.5 found in experiment II in tester strain TA 1535 at a concentration of 100 µg/plate (with metabolic activation) was regarded as not biologically relevant due to lack of a dose-response relationship.

Table 1. Test results of experiment 1 (plate incorporation test).

Bacterial Reverse Mutation Assay, mean revertants colonies/plate ± standard deviation (mutation factor)

EXPERIMENT 1 (plate incorporation test)

S9-Mix

Without

 

Test item (µg/plate)

TA 98

TA 100

TA 1535

TA 1537

TA 102

Aqua dest.

18 ± 3.5 (1.0)

106 ± 7.1 (1.0)

8 ± 4.2 (1.0)

6 ± 0.6 (1.0)

189 ± 13.5 (1.0)

31.6

13± 3.5 (0.7)

106± 9.5 (1.0)

11 ± 2.0 (1.3)

7 ± 5.1 (1.1)

231 ± 22.1 (1.2)

100

21 ± 2.5 (1.1)

102 ± 7.1 (1.0)

8 ± 0.6 (1.0)

6 ± 0.6 (0.9)

206 ± 5.1 (1.1)

316

16 ± 4.7 (0.9)

103 ± 7.2 (1.0)

11 ± 3.2 (1.4)

6 ± 2.0 (0.9)

189 ± 14.2 (1.0)

1000

19 ± 2.1 (1.1)

105 ± 8.2 (1.0)

7 ± 5.0 (0.9)

9 ± 1.5 (1.5)

162 ± 33.5 (0.9)

2500

16 ± 2.6 (0.9)

76 ± 7.5 (0.7)

10 ± 3.1 (1.2)

10 ± 2.9 (1.6)

123 ± 21.2 (0.7)

5000

12 ± 2.6 (0.7)

32 ± 10.1 B (0.3)

2 ± 1.5 (0.2)

3 ± 3.5 (0.5)

50 ± 4.2 (0.3)

4-NOPD

322 ± 32.3 (17.5)

---

---

86 ± 9.5 (13.5)

---

NaN3

---

793 ± 200.3 (7.5)

838 ± 118.5 (100.6)

---

---

MMS

---

---

---

---

1387 ± 171.7 (7.3)

S9-Mix

 

With

Test item (µg/plate)

TA 98

TA 100

TA 1535

TA 1537

TA 102

Aqua dest.

28± 2.3 (1.0)

114± 1.2 (1.0)

10± 1.5 (1.0)

6± 1.5 (1.0)

282± 3.8 (1.0)

31.6

24± 3.5 (0.9)

122± 11.6 (1.1)

8 ± 0 (0.8)

5 ± 1.5 (0.9)

290 ± 7.0 (1.0)

100

21 ± 1.5 (0.8)

110 ± 3.2 (1.0)

6 ± 0.6 (0.7)

4 ± 0.6 (0.8)

285 ± 5.9 (1.0)

316

28 ± 1.2 (1.0)

103 ± 5.5 (0.9)

8 ± 0.6 (0.8)

8 ± 3.2 (1.5)

244 ± 18.0 (0.9)

1000

22 ± 2.5 (0.8)

117 ± 19.3 (1.0)

6 ± 1.5 (0.6)

6 ± 1.4 (1.1)

233 ± 28.4 (0.8)

2500

24 ± 4.2 (0.9)

103 ± 15.9 (0.9)

6 ± 1.7 (0.6)

10 ± 2.5 (1.7)

216 ± 15.3 (0.8)

5000

19 ± 5.0 (0.7)

73 ± 4.0 (0.6)

6 ± 3.2 (0.7)

11 ± 3.6 (1.9)

131 ± 25.7 (0.5)

2-AA

1909 ± 64.1 (69.0)

2180 ± 178.4 (19.1)

161 ± 21.0 (16.7)

208 ± 74.4 (36.6)

595 ± 9.6 (2.1)

B = background lawn reduced

4-NOPD = 4-nitro-o-phenylene-diamine

NaN3= sodium azide

MMS = methylmethanesulfonate

2-AA = 2-Aminoanthracene

Table 2. Test results of experiment 2 (pre-incubation test).

Bacterial Reverse Mutation Assay, mean revertants colonies/plate ± standard deviation (mutation factor)

EXPERIMENT 1 (plate incorporation test)

S9-Mix

Without

 

Test item (µg/plate)

TA 98

TA 100

TA 1535

TA 1537

TA 102

Aqua dest.

18 ± 9.3 (1.0)

114 ± 12.5 (1.0)

12 ± 4.9 (1.0)

5 ± 2.3 (1.0)

205 ± 12.9 (1.0)

10.0

22 ± 5.1 (1.2)

114 ± 9.5 (1.0)

10 ± 3.2 (0.8)

4 ± 0.6 (0.7)

230 ± 12.1 (1.1)

31.6

21 ± 7.9 (1.2)

126 ± 23.5 (1.1)

16 ± 4.2 (1.3)

7 ± 2.6 (1.3)

240 ± 16.1 (1.2)

100

22 ± 5.5 (1.3)

120 ± 21.6 (1.1)

10 ± 1.2 (0.9)

6 ± 0 (1.1)

217 ± 6.8 (1.1)

316

23 ± 3.6 (1.3)

112 ± 15.9 (1.0)

10 ± 3.5 (0.9)

7 ± 4.4 (1.3)

202 ± 7.2 (1.0)

1000

23 ± 3.6 (1.3)

109 ± 1.5 B (1.0)

6 ± 4.8 (0.5)

7 ± 1.7 B (1.3)

175 ± 11.3 (0.9)

2500

7 ± 6.4 B (0.4)

0 ± 0 B (0)

1 ± 0.6 B (0.1)

0 ± 0 B (0)

37 ± 38.2 B (0.2)

5000

3 ± 2.6 B (0.2)

0 ± 0 B (0)

0 ± 0 B (0)

0 ± 0 N (0)

0 ± 0 B (0)

4 -NOPD

1111 ± 127.2 (62.9)

---

---

117 ± 25.4 (21.9)

---

NaN3

---

903 ± 61.7 (7.9)

753 ± 50.0 (64.5)

---

---

MMS

---

---

---

---

1184 ± 57.2 (5.8)

S9-Mix

 

With

Test item (µg/plate)

TA 98

TA 100

TA 1535

TA 1537

TA 102

Aqua dest.

27 ± 1.5 (1.0)

120 ± 6.6 (1.0)

12 ± 6.5 (1.0)

8 ± 1.0 (1.0)

326 ± 15.2 (1.0)

10.0

27 ± 4.4 (1.0)

113 ± 10.7 (0.9)

11 ± 5.0 (0.9)

6 ± 2.0 (0.8)

295 ± 42.1 (0.9)

31.6

28 ± 1.5 (1.0)

124 ± 6.0 (1.0)

11 ± 5.7 (0.9)

8 ± 2.5 (1.0)

324 ± 21.8 (1.0)

100

24 ± 3.8 (0.9)

132 ± 13.7 (1.1)

7 ± 1.5 (0.5)

7 ± 1.0 (0.9)

249 ± 11.3 (0.8)

316

29 ± 9.5 (1.1)

135 ± 4.6 (1.1)

8 ± 1.0 (0.6)

9 ± 2.5 (1.1)

268 ± 22.9 (0.8)

1000

33 ± 6.7 (1.2)

147 ± 16.8 (1.2)

10 ± 2.5 (0.8)

8 ± 1.0 (1.0)

277 ± 9.8 (0.8)

2500

26 ± 1.2 B (1.0)

36 ± 10.8 B (0.3)

9 ± 0.6 B (0.7)

7 ± 5.5 B (0.9)

158 ± 16.1 (0.5)

5000

0 ± 0 N (0)

0 ± 0 B (0)

0 ± 0 N (0)

0 ± 0 N (0)

8 ± 3.5 B (0)

2-AA

2027 ± 277.7 (74.1)

1466 ± 326.5 (12.2)

112 ± 23.3 (9.1)

170 ± 26.3 (21.3)

659 ± 31.5 (2.0)

B = background lawn reduced

N = no background lawn

4-NOPD = 4-nitro-o-phenylene-diamine

NaN3= sodium azide

MMS = methylmethanesulfonate

2-AA = 2-Aminoanthracene

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
negative

In conclusion, it can be stated that during the described mutagenicity test and under the experimental conditions reported, Sodium methyl-4-hydroxybenzoate did not cause gene mutations by base pair changes or frameshifts in the genome of the tester strains used.
Therefore, Sodium methyl-4-hydroxybenzoate is considered to be non-mutagenic in this bacterial reverse mutation assay.
Executive summary:

In a reverse gene mutation assay in bacteria, strains TA98, TA100, TA1535, TA1537 and TA102 of S. typhimurium were exposed to Sodium methyl-4-hydroxybenzoate at concentrations of 31.6, 100, 316, 1000, 2500 and 5000 µg/plate (experiment I)

and 10.0, 31.6, 100, 316, 1000, 2500 and 5000 µg/plate (experiment II), in the presence and absence of mammalian metabolic activation according to the plate incorporation method (experiment I) and the pre-incubation method (experiment II).

Sodium methyl-4-hydroxybenzoate was tested up to the limit concentration of 5000 µg/plate in all tester strains used.

The positive controls induced the appropriate responses in the corresponding strains. There was no evidence of induced mutant colonies over background.

This study is classified as acceptable. This study satisfies the requirement for Test Guideline OPPTS 870.5100; OECD 471 for in vitro mutagenicity (bacterial reverse gene mutation) data.