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Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro cytogenicity / chromosome aberration study in mammalian cells
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2001-01-08 to 2001-02-08
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with national standard methods

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2001
Report Date:
2001

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
JAPAN: Guidelines for Screening Mutagenicity Testing Of Chemicals
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)
GLP compliance:
yes
Type of assay:
in vitro mammalian chromosome aberration test

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
not specified

Method

Species / strain
Species / strain / cell type:
mammalian cell line, other: Chinese hamster lung I/U
Metabolic activation:
with and without
Metabolic activation system:
phenobarbital and 5,6-benzoflavone induced rat liver S9
Test concentrations with justification for top dose:
5, 10, 20, 40, 80%
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: HEPA filtered air
- Justification for choice of solvent/vehicle: none given in study report
Controlsopen allclose all
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
Remarks:
air
True negative controls:
no
Positive controls:
yes
Positive control substance:
mitomycin C
Remarks:
without metabolic activation
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
Remarks:
air
True negative controls:
no
Positive controls:
yes
Positive control substance:
benzo(a)pyrene
Remarks:
with metabolic activation
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
Remarks:
air
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: methylchloride
Remarks:
without metabolic activation
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
Remarks:
air
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: vinylchloride
Remarks:
with metabolic activation
Details on test system and experimental conditions:
METHOD OF APPLICATION: other: the test gas or the positive control gas was supplied at fixed concentrations to square glass culture vessels which were then rotated at 1 rpm, so that the cells were directly and repeatedly exposed to a gas and then to a medium solution for a fixed period of time during rotation.

DURATION
- Exposure duration: 6 hours (short treatment with and without metabolic activation) 24 and 48 hours (continuous treatment, without metabolic activation)
- Expression time (cells in growth medium): 18 hours (short treatment)
- Fixation time (start of exposure up to fixation or harvest of cells): 24 or 48 hours

SPINDLE INHIBITOR (cytogenetic assays): Colcemid added 2 hours before chromosome preparations made.
STAIN (for cytogenetic assays): Giesma

NUMBER OF REPLICATIONS: duplicate cultures

NUMBER OF CELLS EVALUATED: 100 cells per culture

DETERMINATION OF CYTOTOXICITY
- Method: mitotic index; cell growth index

OTHER EXAMINATIONS:
- Determination of polyploidy: yes
- Determination of endoreplication: yes


_ METABOLIC ACTIVATION:
phenobarbital and 5,6-benzoflavone induced rat liver S9 was purchased from Kikkoman Co., containing 26.02 mg/ml protein. S9 mix contained 30% S9, and glucose-6-phosphae, NADP and NADPH as co-factors. Final concentration of S9 was 5%.
Evaluation criteria:
Cells were examined for chromatid breaks and exchanges; chromosome breaks and exchanges; fragmentation; gaps; polyploidy; endoreduplication. Substances which caused more than 10% aberrations were considered as positive.
Statistics:
No statistical analysis was performed

Results and discussion

Test results
Key result
Species / strain:
mammalian cell line, other: CHL/IU
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid

Any other information on results incl. tables

Summary of results of chromosome aberration study

Preliminary test, 6 hours exposure, without metabolic activation

Concentration

(%)

Cells observed

Growth Index

% cells with aberrations

% cells with gaps

 

% cells with polyploidy

 

0*

100

100

0

0

0

5

100

87

1

0

0

10

100

102

0

0

0

20

100

101

0

0

0

40

100

89

0

1

1

80

100

92

0

0

0

Positive control

100

-

63

0

0

Preliminary test, 6 hours exposure, with metabolic activation

Concentration

(%)

Cells observed

Growth Index

% cells with aberrations

% cells with gaps

 

% cells with polyploidy

 

0*

100

100

0

0

0

5

100

97

0

0

1

10

100

104

2

0

1

20

100

104

0

0

0

40

100

94

0

0

0

80

100

86

0

0

0

Positive control

100

-

29

0

3.9

Main test, 6 hours exposure, without metabolic activation

Concentration

(%)

Cells observed

Growth Index

% cells with aberrations

% cells with gaps

 

% cells with polyploidy

 

0*

200

100

0.5

0

0

20

200

103

1.0

0

0

40

200

102

0

0

0

60

200

93

0

0

0.5

80

200

94

0.2

0

1.5

Positive control

200

-

33

0

0

Main test, 6 hours exposure, with metabolic activation

Concentration

(%)

Cells observed

Growth Index

% cells with aberrations

% cells with gaps

 

% cells with polyploidy

 

0*

200

100

0

0

0

20

200

92

0

0

0

40

200

93

0.5

0

0

60

200

93

0

0

0.5

80

200

72

0.5

0

0

Positive control

200

-

49

0

0.5

Preliminary test 24 hours exposure, without metabolic activation

Concentration

(%)

Cells observed

Growth Index

% cells with aberrations

% cells with gaps

 

% cells with polyploidy

 

0*

100

100

0

0

1

5

100

104

2

0

0

10

100

101

0

0

1

20

100

85

0

1

0

40

100

82

0

0

2

80

100

66

 

0

2

Positive control

100

-

42

1

0

Preliminary test 48 hours exposure, without metabolic activation

Concentration

(%)

Cells observed

Growth Index

% cells with aberrations

% cells with gaps

 

% cells with polyploidy

 

0*

100

100

0

0

1

5

100

92

0

0

0

10

100

96

0

0

0

20

100

76

0

0

0

40

100

72

0

0

1

80

100

61

0

0

1

Positive control

100

-

41

1

0

Main test 24 hours exposure, without metabolic activation

Concentration

(%)

Cells observed

Growth Index

% cells with aberrations

% cells with gaps

 

% cells with polyploidy

 

0*

200

100

1

0

0.5

20

200

92

0

0

0

40

200

84

0.5

0

0

60

200

66

0

0

1.0

80

200

60

0

0

1.0

Positive control

200

-

61

3.5

0

Main test 48 hours exposure, without metabolic activation

Concentration

(%)

Cells observed

Growth Index

% cells with aberrations

% cells with gaps

 

% cells with polyploidy

 

0*

200

0

0.5

100

0

20

200

0

0

97

0

40

200

0

0

98

1.5

60

200

0

0

84

2

80

200

0

0

73

1.5

Positive control

200

5

64.5

-

0

* Solvent control (air)

Applicant's summary and conclusion

Conclusions:
Trimethylsilane has been tested according to a national standard method (Japanese) that is equivalent to OECD 473, and in compliance with GLP. No increase in the incidence of chromosome aberrations was observed when tested using a gas exposure method at concentrations up to 80% with and without metabolic activation in Chinese hamster lung cells. Appropriate vehicle and positive controls were used and gave expected results. It is concluded that the test material is negative for the induction of chromosome aberrations under the conditions of the test.