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Toxicological information

Genetic toxicity: in vivo

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Administrative data

Endpoint:
in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus
Remarks:
Type of genotoxicity: chromosome aberration
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study was conducted according to a test protocol that is comparable to the appropriate OECD test guideline, and in compliance with GLP, wiht acceptable rextrictions. The restrictions were that only 1000 erythrocytes were scored for micronuclei.

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:
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

Reference
Name:
Unnamed
Type:
Constituent

Test animals

Species:
mouse
Strain:
Swiss Webster
Sex:
male/female
Details on test animals 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 proecedure 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:
Chloropropyltrimethoxysilane (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 chloropropyltrimethoxysilane (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 chloropropyltrimethoxysilane.
Frequency of treatment:
Single dose
Post exposure period:
30, 48 and 72 hours
Doses / concentrations
Remarks:
Doses / Concentrations:
0 (corn oil), 500, 1000 or 1625 mg/kg
Basis:
nominal conc.
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, probabilty value of <0.05 (1-tailed) used as critical level for significance.

Results and discussion

Test results
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:
Interpretation of results (migrated information): negative
In a valid study according to a protocol similar to OECD 473 and under GLP, Chloropropyltrimethoxysilane 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 periperal erythrocytes of mice under the conditions of the test.
after treatment with a single dose by intraperitoneal injection. Therefore, chloropropyltrimethoxysilane was not
considered to be an inducer of micronuclei in male or female Swiss-Webster mice under the conditions of the in vivo
assay.