3-(trimethoxysilyl)propyl isocyanate

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

Study period:

2011-02-16 - 2011-03-10

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The study was compliant with the 1997 guideline, which was current at the time of the study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2011

Report date:

2011

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

Version / remarks:

2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

micronucleus assay

Test material

Test material information

Constituent 1

Reference substance name:

3-(trimethoxysilyl)propyl isocyanate

EC Number:

239-415-9

EC Name:

3-(trimethoxysilyl)propyl isocyanate

Cas Number:

15396-00-6

Molecular formula:

C7H15NO4Si

IUPAC Name:

(3-isocyanatopropyl)trimethoxysilane

Test material form:

liquid

Test animals

Species:

mouse

Strain:

other: Albino HSD

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Laboratories UK Ltd
- Age at study initiation: 6 - 10 weeks old
- Weight at study initiation: 20 - 30 g
- Assigned to test groups randomly: yes
- Fasting period before study: no information
- Housing: Groups of up to 7 in solid floor polypropylene cages with wood flake bedding
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 - 25°C
- Humidity (%): 30 - 70%
- Air changes (per hr): Approx 15 per hour
- Photoperiod (hrs dark / hrs light): 12 dark /12 light

IN-LIFE DATES: From: 2011-02-22 To: 2011-03-10 .

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

- Vehicle(s)/solvent(s) used: arachis oil
- Justification for choice of solvent/vehicle: None given
- Amount of vehicle (if gavage or dermal): 10 ml/kg
- Lot/batch no. (if required): V-4855
.

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: Arachis oil was used as vehicle. Dosing volume was 10 ml/kg.

All animals were dosed once by gavage using a metal cannula attached to a graduated syringe.

Duration of treatment / exposure:

24 and 48 hours

Frequency of treatment:

Once

Post exposure period:

24 and 48 hours

Doses / concentrations

Remarks:

Doses / Concentrations:
250 -1000 mg/kg bw
Basis:
other: gavage

No. of animals per sex per dose:

7 male mice

Control animals:

yes

Positive control(s):

- cyclophosphamide;
- Justification for choice of positive control(s): Cyclophosphamide is known to produce micronuclei under the conditions of the test
- Route of administration: oral - gavage
- Doses / concentrations: 50 mg/kg - 5 mg/ml

Examinations

Tissues and cell types examined:

Polychromatic erythrocytes (PCE) were scored for micronuclei and normochromatic erythrocytes (NCE) were counted from bone marrow smears

Details of tissue and slide preparation:

CRITERIA FOR DOSE SELECTION: The maximum tolerated dose level or that which produces some evidence of toxicity up to a maximum recommended dose of 2000 mg/kg.

TREATMENT AND SAMPLING TIMES (in addition to information in specific fields): Animals were dosed once and sampled at 24 and 48 hours.

DETAILS OF SLIDE PREPARATION: Immediately following termination both femurs were dissected from each animal, prepared and stained in May-Grunwald/Giemsa, air dried and mounted with a cover slip.

METHOD OF ANALYSIS: Slides were coded and examined under a microscope x1000 magnification.

Evaluation criteria:

A positive mutagenic response would be demonstrated when a statistically significant, dose-responsive, toxicologically relevant increase in the number of micronucleated polychromatic erythrocytes was observed for either the 24 or 48-hour kill times when compared to the vehicle control group. If these criteria were not fulfilled, then the test item would be considered non-genotoxic under the conditions of the test.

Statistics:

The Student's t-test (two tailed) was used and any significant results were confirmed using the one way analysis of variance.

Results and discussion

Test results

Sex:

male

Genotoxicity:

negative

Toxicity:

yes

Remarks:

reduction in PCE/NCE ratio was observed in the 1000 mg/kg test group relative to the vehicle group.

Vehicle controls validity:

valid

Negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

RESULTS OF RANGE-FINDING STUDY
- Dose range: 1000 - 2000 mg/kg bw
- Solubility: The test item was formulated 2 hours before application and was assumed stable for this duration.
- Clinical signs of toxicity in test animals: Animals above 1000 mg/kg bw showed clinical signs of excessive toxicity which included hunched posture, pilo-erection, splayed gait, ataxia, ptosis, dehydration, lethargy, decreased respiratory rate and laboured respiration.
- Evidence of cytotoxicity in tissue analyzed: Not examined
- Rationale for exposure: "It was considered unnecessary to investigate the intraperitoneal route of administration as there was evidence of marked toxicity via the oral route. No sex-related differences were observed, so only male mice were treated in the micronucleus study."
- Harvest times: 24 and 48 hours
- High dose with and without activation: 1000 mg/kg bw, no metabolic activation was used


RESULTS OF DEFINITIVE STUDY
- Induction of micronuclei (for Micronucleus assay): negative
- Ratio of PCE/NCE (for Micronucleus assay): Modest decreases in PCE/NCE ratio were observed in both 24 and 48-hour 1000mg/kg dose groups when compared to the vehicle control group.
- Appropriateness of dose levels and route: Dose levels and route were appropriate.
- Statistical evaluation: no statistically significant effects were observed.
- Other: Two premature deaths were observed in the 48-hour 1000 mg/kg dose group and one premature death was observed in the 24-hour 500 mg/kg dose group. The deaths were considered to be due to variable sensitivity of the mice to the test item.

Any other information on results incl. tables

Table 3 Results of micronucleus assay

Treatment group mg/kg bw and sample time	Number of PCE with micronuclei per 2000 PCE		PCE/NCE Ratio
	Group Mean	SD	Group Mean	SD
Control 24 hour	2.4	2.5	0.87	0.33
1000 48 hour	1.6	2.3	0.67	0.16
1000 24 hour	2.7	3.0	0.57	0.17
500 24 hour	1.5	1.0	0.78	0.13
250 24 hour	0.4	0.8	0.80	0.15
Positive control 24 hour	31.2**	14.4	0.71	0.09

 

** = P<0.001

Applicant's summary and conclusion

Conclusions:

3-(Trimethoxysilyl)propyl isocyanate has been tested in a reliable micronucleus assay according to OECD TG 474 and in compliance with GLP. No statistically significant increase in the frequency of micronucleated polychromatic erythrocytes was observed in peripheral erythrocytes of mice treated with the test substance by oral gavage. Appropriate vehicle and positive controls were included and gave expected results. It is concluded that 3-(trimethoxysilyl)propyl isocyanate is negative for the induction of micronuclei under the conditions of this test.