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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:
2004-04-26 to 2004-2004-05-24
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
The study was conducted according to the appropriate OECD test guideline, and in compliance with GLP.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2004
Report Date:
2004

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)
Deviations:
no
GLP compliance:
yes
Type of assay:
in vitro mammalian chromosome aberration test

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent

Method

Species / strain
Species / strain / cell type:
lymphocytes: Human blood
Metabolic activation:
with and without
Metabolic activation system:
phenobarbitone and naphthoflavone induced rat liver S9
Test concentrations with justification for top dose:
9.7, 19.41, 38.81, 77.63, 155.25*, 310.5*, 621*, 1242, 1863, 2484 µg/ml (* analysed concentrations)
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: DMSO

- Justification for choice of solvent/vehicle: Solubility properties and relative non-toxicity to bacteria
Controlsopen allclose all
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
cyclophosphamide
Remarks:
(with activation)
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
mitomycin C
Remarks:
(without activation)
Details on test system and experimental conditions:
METHOD OF APPLICATION: in medium

ACTIVATION: 1ml of 20 % S9 mix ( ie 2 % final concentration of S9 in standard co-factors) was added to the cultures.

DURATION

- Exposure duration: 4 hours
- Expression time (cells in growth medium): 20 hours

SPINDLE INHIBITOR (cytogenetic assays): Colcemid

STAIN (for cytogenetic assays): Gurrs Giemsa


NUMBER OF REPLICATIONS: 2 cultures per dose level


NUMBER OF CELLS EVALUATED: 950 in total. (150 for positive control, 200 for treatments and vehicle control)


DETERMINATION OF CYTOTOXICITY
- Method: mitotic index, relative total growth


OTHER EXAMINATIONS:
- Determination of polyploidy: mean frequency % for experiment 1
Evaluation criteria:
A positive response was recorded if the % of cells with aberrations, excluding gaps, markedly exceeded that seen in the concurrent control, with or
without a clear dose-relationship. For modest increases in aberration frequency a dose response relationship is generally required and appropriate
statistical tests may be applied in order to record a positive response

Results and discussion

Test resultsopen allclose all
Species / strain:
lymphocytes: human blood
Metabolic activation:
without
Genotoxicity:
positive
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
50% mitotic inhibition at 310.5 μg/ml
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
Species / strain:
lymphocytes: human blood
Metabolic activation:
with
Genotoxicity:
positive
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
73% mitotic inhibition at 2484 μg/ml
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
Additional information on results:
COMPARISON WITH HISTORICAL CONTROL DATA: Results were within range of historical control data

Any other information on results incl. tables

Table 3: Results of chromosome analysis Experiment 1, 4h treatment without activation (total count from 2 cultures)

 

Solvent*

Control**

Positive

Control***

621 μg/ml**

310.5 μg/ml**

155.25 μg/ml**

Cytotoxicity

No

Yes

No

Yes

Yes

 

Mean

Chromatid aberrations

gaps

2

20

33

14

8

breaks

1

25

36

10

5

interchanges

1

33

28

1

0

Chromosome

aberrations

gaps

NR

NR

NR

NR

NR

breaks

0

2

4

3

1

interchanges

0

1

0

0

0

Mitotic index (%)

100

49

16

50

80

Polyploidy (% mean freq.)

0.5

0

0

0.5

0

Endo reduplication

NR

NR

NR

NR

NR

 *Solvent control with DMSO

** Per 200 cells

*** Per 150 cells

NR not reported

Table 4: Results of chromosome analysis Experiment 1, 4h treatment with activation (total count from 2 cultures)

 

Solvent*

Control**

Positive

Control***

621 μg/ml**

1242 μg/ml**

1863

μg/ml**

2484

μg/ml***

Cytotoxicity

No

Yes

No

No

No

Yes

 

Mean

Chromatid aberrations

gaps

0

39

8

8

26

27

breaks

0

47

1

4

25

42

interchanges

0

33

0

3

7

14

Chromosome aberrations

gaps

NR

NR

NR

NR

NR

NR

breaks

1

3

1

3

5

5

interchanges

0

0

0

0

0

1

Mitotic index (%)

100

19

117

70

57

27

Polyploidy (% mean freq.)

0

0

0

0

1.5

0

Endo reduplication

NR

NR

NR

NR

NR

NR

 *Solvent control with DMSO

** Per 200 cells

*** Per 100 cells

NR not reported

Applicant's summary and conclusion

Conclusions:
I[3-(2,3-epoxypropoxy)propyl]diethoxy(methyl)silane has been tested in a study carried out according OECD 473 and in compliance with GLP. The test material induced a statistically significant dose-related increase in the frequency of cells with chromosome aberrations in both the absence and presence of metabolic activation. Appropriate solvent and positive controls were included and gave expected results. The test material was therefore considered to be clastogenic to human lymphocytes in vitro under the conditions of the study.