Sulphur dioxide

Genetic toxicity: in vitro

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

Test material information

Constituent 1

Reference substance name:

Sulphur dioxide

EC Number:

231-195-2

EC Name:

Sulphur dioxide

Cas Number:

7446-09-5

Molecular formula:

SO2

IUPAC Name:

Sulphur dioxide generated from sulphur by combustion

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.