3-chloropropyltrimethoxysilane

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1993

Report date:

1993

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

Deviations:

yes

Remarks:

only 1000 PCE scored for micronuclei

GLP compliance:

yes

Type of assay:

micronucleus assay

Test material

Test material information

Constituent 1

Test animals

Species:

mouse

Strain:

Swiss Webster

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River laboratories
- Age at study initiation: 5 weeks
- Weight at study initiation: 22-7 to 25.5 g (males); 17.9 to 21.4 g (females)
- Assigned to test groups randomly: yes, under following basis: nonstratified randomization procedure based on body weight
- Fasting period before study: no
- Housing: group housed in shoe box type plastic cages
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 1 week

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22°C
- Humidity (%): 40-70%
- Air changes (per hr): no information
- Photoperiod (hrs dark / hrs light): 12/12


IN-LIFE DATES: From: 1991-07-08 To: 1991-09-03

Administration / exposure

Route of administration:

intraperitoneal

Vehicle:

- Vehicle(s)/solvent(s) used: corn oil;
- Justification for choice of solvent/vehicle: none given - standard vehicle

Details on exposure:

(3-Chloropropyl)trimethoxysilane (CAS No. 2530-87-2) was given to both male and female Swiss-Webster mice as a single dose by intraperitoneal injection. Based upon mortality data obtained in a range-finding study, the acute intraperitoneal LD50 for the combined sexes was calculated to be 2031 mg/kg (3-Chloropropyl)trimethoxysilane (95% confidence interval, 1672 to 2456 mg/kg).  The doses for the definitive micronucleus assay were selected by the study director as approximately 25%, 50%, and 90% of the LD50 or 500, 1000, and 1625 mg/kg (3-Chloropropyl)trimethoxysilane.

Frequency of treatment:

Single dose

Post exposure period:

30, 48 and 72 hours

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

0 other: mg/kg

Remarks:

Nominal concentration. Control, corn oil

Doses / concentrations 2

Dose / conc.:

500 other: mg/kg

Remarks:

Nominal concentration

Doses / concentrations 3

Dose / conc.:

1 000 other: mg/kg

Remarks:

Nominal concentration

Doses / concentrations 4

Dose / conc.:

1 625 other: mg/kg

Remarks:

Nominal concentration

No. of animals per sex per dose:

5 per sex per dose, except high dose where 8/sex/dose were used

Control animals:

yes, concurrent vehicle

Positive control(s):

- triethylenemelamine
- dissolved in ethanol then diluted with sterile distilled water
- Justification for choice of positive control(s): none given, standard control
- Route of administration: ip
- Doses / concentrations:0.3 mg/kg

Examinations

Tissues and cell types examined:

Peripheral erythrocytes

Details of tissue and slide preparation:

CRITERIA FOR DOSE SELECTION: based on toxicity data

DETAILS OF SLIDE PREPARATION: 1 or 2 blood smear slides prepared per animal, stained with Gurr's R-66 Giesma

METHOD OF ANALYSIS: PEC: PNEC ratio for 1000 cells per animal calculated to estimate toxicity. 100 PCE/animal scored for presence of micronuclei

Statistics:

Mann-Whitney U test, probability value of <0.05 (1-tailed) used as critical level for significance.

Results and discussion

Test results

Key result

Sex:

male/female

Genotoxicity:

negative

Toxicity:

yes

Remarks:

PCE/NCE ratio decreased at 72 h, high dose

Vehicle controls validity:

valid

Negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

There were no signs of toxicity in male or female mice in the 500 mg/kg group, except that 1 female exhibited ataxia during the first hour post-treatment. All of the males and females in the 1000 mg/kg group exhibited ataxia and 2 of the males also had tremors during the first hour after treatment. In males and females treated at 1625 mg/kg chloropropyltrimethoxysilane, ataxia, tremors, and prostration were observed during the first hour after treatment. Other clinical signs in the high dose females included myoclonic jerks and vocalization. There were no significant clinical observations in male or female mice from the afternoon of Day 1 through the end of the study.  

There was a significant decrease in the polychromatophilic erythrocyte (PCE) to normochromatophilic erythrocyte (NCE) ratios at the 72 hr sampling  time among male mice (50.6% of control) treated with 1625 mg/kg cloropropyltrimethoxysilane. However, there was no evidence that chloropropyltrimethoxysilane was excessively toxic to the bone marrow at the concentrations chosen for the study. No significant increases in the incidences of micronucleated PCE were observed at 500, 1000, or 1625 mg/kg chloropropyltrimethoxysilane at the 30, 48 or 72 hr sampling times in mice of either sex.

RESULTS OF RANGE-FINDING STUDY
- Dose range: information not included in study report
- Rationale for exposure: based on ip LD50

RESULTS OF DEFINITIVE STUDY
- Induction of micronuclei (for Micronucleus assay): negative
- Ratio of PCE/NCE (for Micronucleus assay): decreased
- Appropriateness of dose levels and route: yes
- Statistical evaluation: yes

Any other information on results incl. tables

Table 2 Results of in vivo micronucleus test

Treatment			Solvent control	Low dose	Mid dose	High dose	Positive control
Sampling time			30 h
Number of erythrocytes	normochromatic (NCE)	m	NR	NR	NR	NR	NR
		f	NR	NR	NR	NR	NR
	polychromatic (PCE)	m	5000	5000	5000	5000	5000
		f	5000	5000	5000	5000	5000
	PCE with micronuclei (MPCE)	m	12	13	15	12	061
		f	9	5	4	11	67
Ratio of erythrocytes	PCE/1000 NCE	m	34	35	33	28.4	24.6
		f	28.4	35	29.6	29.0	28.4
	MPCE/NCE (%)	m	0.24	0.26	0.30	0.24	1.22
		f	0.18	0.10	0.08	.22	1.34
Sampling time			48 h
Number of erythrocytes	normochromatic (NCE)		NR	NR	NR	NR	NE
	polychromatic (PCE)	b	10000	10000	10000	10000	NE
Ratio of erythrocytes	PCE with micronuclei (MPCE)		20	24	16	17	NE
	PCE/1000 NCE	m	26.8	24.4	23.4	19.8	NE
		f	24.8	23.2	22.4	23.8	NE
	MPCE/NCE (%)		0.2	0.24	0.16	0.17	NE
		72 h
	polychromatic (PCE)	b	10000	10000	10000	10000	NE
	PCE with micronuclei (MPCE)	b	16	15	16	16	NE
	PCE/NCE (%)	b	0.16	0.15	0.16	0.16	NE
	MPCE/NCE	m	35.2	30.8	26.8	17.8*	NE
		f	29.2	33.6	31.4	20.4	NE

* significantly different from control, p<0.01

b both sexes combined

NR not recorded

NE not evaluated

Applicant's summary and conclusion

Conclusions:

(3-Chloropropyl)trimethoxysilane has been tested for clastogenicity in a valid in vivo micronucleus study, according to a protocol similar to OECD Test Guideline 474 and in compliance with GLP. (3-Chloropropyl)trimethoxysilane did not produce significant, treatment-related increases in the incidence of micronucleated polychromatophilic erythrocytes among male or female Swiss-Webster mice assessed at 30, 48 or 72 hours . It is concluded that the test substance is negative for the induction of micronuclei in peripheral erythrocytes of mice under the conditions of the test after treatment with a single dose by intraperitoneal injection. Therefore, (3-chloropropyl)trimethoxysilane was not considered to be an inducer of micronuclei in male or female Swiss-Webster mice under the conditions of the in vivo assay.