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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:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Entry adopted from the OECD SIAR on sulfur dioxide without modification.Study meets generally accepted scientific principles, study less well documented especially with regard to the testing procedures; study acceptable for assessment.

Data source

Reference
Reference Type:
publication
Title:
In vitro and ex vivo effects of the air pollutants SO2 and NOx on benzo(a)pyrene activating enzymes of the rat liver
Author:
Pool-Zobel, B.L.; et al.1990
Bibliographic source:
Exp. Pathol. 39, 207-212

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Study only reports on isolated mechanistic investigations:
Investigation of comutagenic activity. Exposure of S. typhimurium TA 98 to 50 ppm SO2 (control air) on plates containing B(a)P in various concentrations (0-5 µ/plate).
GLP compliance:
not specified
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Sulphur dioxide (SO2)
- Physical state: gaseous
- no further significant details stated

Method

Species / strain
Species / strain / cell type:
S. typhimurium TA 98
Metabolic activation:
with
Metabolic activation system:
liver S9 from male Sprague Dawley rats pretreated with Aroclor or exposed to 50 ppm sulfur dioxide for 2 weeks
Test concentrations with justification for top dose:
- 0-5.00 µg/plate benzo(a)pyrene
- 50 ppm SO2 gas (coincubation)
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: no vehicle used for SO2 exposure; benzo(a)pyrene was contained in the agar plate
- no further significant details stated
Controls
Untreated negative controls:
yes
Remarks:
control plates were exposed to air or sulphur dioxide alone
Negative solvent / vehicle controls:
other: not applicable
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 5 µg 2-aminoanthracene
Details on test system and experimental conditions:
- the mutagenic activity of benzo(a)pyrene was assayed in the plate incorporation test during coincubation with sulphur dioxide gas

METHOD OF APPLICATION:benzo(a)pyrene in agar (plate incorporation); SO2 as gas

- Exposure duration: 48 h exposure to SO2
- replications: three plates per concentration; each assay was repeated at least twice

- no further significant details stated
Evaluation criteria:
- reversion to histidin prototrophy was determined with the plate incorporation assay
Statistics:
no data

Results and discussion

Test results
Species / strain:
S. typhimurium TA 98
Metabolic activation:
with
Genotoxicity:
negative
Remarks:
no increased revertant rates in the presence of sulphur dioxide or S9 from sulphur dioxide-pretreated rats
Cytotoxicity / choice of top concentrations:
not specified
Vehicle controls validity:
other: not applicable
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
- no further significant data stated
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Any other information on results incl. tables

No increased rate of revertants was found in the Ames test with S. typh. TA98 exposed exclusively to 50 ppm sulphur dioxide for 48 hours in the presence of S9. Furthermore sulphur dioxide co-exposure did not increase the mutagenic activity of benzo(a)pyrene. S9 from sulphur dioxide pretreated rats did not activate benzo(a)pyrene to the ultimate mutagen as mutagenic activity was completely absent.

Table 1: assay for mutagenic activity of high B(a)P-doses

Concentration µg/plate

His+ revertants

air

SO2

0

49±4

46±7

1.25

177±7

212±24

2.50

190±16

195±9

5.00

194±7

191±3

PC

952±61

1358±147

0

47±8

45±8

125

149±30

153±37

2.50

165±12

145±20

5.00

163±11

166±5

PC

1025±79

1515±136

0

37±7

38±5

125

198±47

205±21

2.50

219±32

268±47

5.00

226±15

232±3

PC

868±20

979±70

PC: positive control

Table 2: assay for mutagenic activity of low B(a)P-doses

Concentration µg/plate

His+ revertants

air

SO2

0

32±3

30±1

0.3125

131±14

92±10

0.625

208±9

210±10

1.25

252±4

209±11

PC

1239±77

1255±70

0

46±13

31±5

0.3125

86±4

77±3

0.625

122±12

119±14

1.25

160±39

155±8

PC

1631±55

1259±70

0

57±11

39±1

0.3125

138±6

120±5

0.625

187±11

171±9

1.25

213±11

213±26

PC

1380±22

1185±43

PC: positive control

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
negative

No increased rate of revertants was found in the Ames test with S. typh. TA98 exposed exclusively to 50 ppm sulfur dioxide for 48 hours in the presence of S9. Furthermore sulfur dioxide co-exposure did not increase the mutagenic activity of benzo(a)pyrene. S9 from sulfur dioxide pretreated rats did not activate benzo(a)pyrene to the ultimate mutagen as mutagenic activity was completely absent.