Reaction mass of [3-(trimethoxysilyl) propyl]urea, [3-(dimethoxyethoxysilyl) propyl]urea, [3-(methoxydiethoxysilyl) propyl]urea and [3-(triethoxysilyl) propyl]urea.

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Type of information:

experimental study

Adequacy of study:

key study

Study period:

13 Oct - 08 Nov 1999

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2000

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)

Version / remarks:

adopted 1997

Deviations:

no

GLP compliance:

yes

Type of assay:

other: in vitro mammalian chromosome aberration test (migrated information)

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

449-160-7

EC Name:

-

Cas Number:

116912-64-2

Molecular formula:

C7H18N2O4Si C8H20N2O4Si C9H22N2O4Si C10H24N2O4Si

IUPAC Name:

[3-(ethoxydimethoxysilyl)propyl]urea; [3-(trimethoxysilyl)propyl]urea; {3-[diethoxy(methoxy)silyl]propyl}urea

Method

Species / strain

Species / strain / cell type:

lymphocytes:

Details on mammalian cell type (if applicable):

Peripheral lymphocytes from healthy human males were cultured within 4 h after blood sampling. The cells were cultured in Ham´s F10 without thymidine and hypoxanthine supplemented with fetal calf serum, L-glutamine, P/S, sodium bicarbonate and heparin.

Metabolic activation:

with and without

Metabolic activation system:

S9 from livers of Aroclor 1254 induced male Wistar rats

Test concentrations with justification for top dose:

Without S9-mix: 100, 180, 333, 420, 560 µg/ml
With S9-mix: 333, 560, 1000, 1300, 1800 µg/ml

Vehicle / solvent:

Dimethylsulphoxide (final concentration 0.9%)

Controls

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: +S9: Cyclophosphamide, 15 µg/ml; -S9: Mitomycin C, 0.5, 0.2 and 0.1 µg/ml for 3, 24 and 48 h treatment, respectively.

Details on test system and experimental conditions:

METHOD OF APPLICATION: in suspension

DURATION
- Exposure duration: 3 h
- Fixation time (start of exposure up to fixation or harvest of cells): 24 h

SPINDLE INHIBITOR (cytogenetic assays): Colchicine (0.5 µg/ml) was added 3 h before fixation of cells.
STAIN (for cytogenetic assays): Giemsa (5% in tap water)

NUMBER OF REPLICATIONS: duplicate

NUMBER OF CELLS EVALUATED: 100 metaphase chromosome spreads per culture

DETERMINATION OF CYTOTOXICITY
- Method: mitotic index (metaphases per 1000 cells)

OTHER EXAMINATIONS:
- Determination of polyploidy: no data
- Determination of endoreplication: no data
- Range finding test: cells were treated for 3 (fixation at 24 h, ± S9), 24 (fixation at 24 h, -S9), and 48 h (fixation at 48 h, -S9) for determination of mitotic index.

Evaluation criteria:

A test substance was considered positive (clastogenic) if:
- induction of a dose-related statistically significant increase in the number of cells with chromosomal aberrations.
- a statistically significant increase in the frequencies of the number of cells with chromosome aberrations as observed in the absence of a clear dose-response relationship.

Statistics:

- induction of a dose-related statistically significant increase in the number of cells with chromosomal aberrations: Chi-square test, p<0.05

Results and discussion

Test results

Species / strain:

lymphocytes: human

Metabolic activation:

with and without

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

Mitotic index < 50% at the highest concentration ± S9

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH: pH 7.54 was measured at the highest concentration of 5000 µg/ml (pH 7.67 in the solvent control)
- Effects of osmolality: 385 mOsm/kg was measured at the highest concentration of 5000 µg/ml (428 mOsm/kg in the solvent control)

RANGE-FINDING/SCREENING STUDIES: for details see table 1

COMPARISON WITH HISTORICAL CONTROL DATA: Solvent control data were within the historical control data

Any other information on results incl. tables

Table 1: Results determined in the range-finder assay:

Test item	Concentration	Mitotic Index
	in µg/ml	in %
Exposure period 3 h, fixation time 24 h, without S9 mix
Test substance	100	93
	333	66
	1000	7
	3333	0
	5000	0
Exposure period 24 h, fixation time 24 h, without S9 mix
Test substance	100	110
	333	28
	1000	0
	3333	0
	5000	0
Exposure period 48 h, fixation time 48 h, without S9 mix
Test substance	100	79
	333	15
	1000	0
	3333	0
	5000	0
Exposure period 3 h, fixation time 24 h, with S9 mix
Test substance	100	120
	333	104
	1000	56
	3333	0
	5000	0

Table 2: Results of the cytogenicity assay:

Test item	Concentration	Mitotic Index	Aberrant cells in %
	in µg/ml	in %	with gaps	without gaps
Exposure period 3 h, fixation time 24 h, without S9 mix
DMSO	0.9% (v/v)	100	1	1
MMC	0.5	113	9	8
Test substance	180	101	7	6
	333	69	16	13
	420	39	18	15
Exposure period 3 h, fixation time 24 h, with S9 mix
DMSO	0.9% (v/v)	100	1	1
CP	15	31	32	32
Test substance	333	99	2	2
	560	84	4	3
	1000	48	19	15

Applicant's summary and conclusion

Conclusions:

Interpretation of results: positive

In a chromosomal aberration assay according to OECD 473 and GLP, a genotoxic effect was observed for the test substance tested in a 3 h treatment in two independent experiments without and with metabolic activation. Appropriate solvent and positive controls were included and gave expected results. The test substance is genotoxic under the test conditions applied.