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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
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Dec 2002 - Mar 2003
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Data source

Referenceopen allclose all

Reference Type:
publication
Title:
Unnamed
Year:
2003
Reference Type:
study report
Title:
Unnamed
Year:
2003
Report date:
2011

Materials and methods

Principles of method if other than guideline:
Peripheral blood samples were obtained from male and female B6C3F1 mice at the end of a 14-week toxicity study. Smears were immediately prepared and fixed in absolute methanol, stained with a chromatin-specific fluorescent dye mixture of Hoechst 33258/pyronin Y and coded. Slides were scanned at 630 or 1000 times magnification using a semi-automated image analysis system to determine the frequency of micronuclei in 10000 normochromatic erythrocytes (NCEs) in each of 10 animals per dose group. A detailed discussion of this assay can be found in MacGregor et al. (1990).
GLP compliance:
no
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Specific details on test material used for the study:
- Physical state: colorless liquid with a strong ammonia odor
- Analytical purity: approximately 99.9%
- Lot/batch No.: BE/07/01
- Stability under test conditions: no degradation of the bulk chemical was detected
- Storage condition of test material: at controlled room temperature

Test animals

Species:
mouse
Strain:
B6C3F1
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Taconic Farms, Inc. (Germantown, NY)
- Age at study initiation: approximately 6 weeks
- Weight at study initiation: males: 23.3 g (mean), female: 19.8 g (mean)
- Housing: individually in stainless steel wire bottom (Lab Products, Inc., Seaford, DE), changed weekly and rotated daily
- Diet: NTP-2000 irradiated wafers (Zeigler Brothers, Inc., Gardners, PA), available ad libitum, except during exposure periods
- Water: Tap water (Richland municipal supply) via automatic watering system (Edstrom Industries, Waterford, WI), available ad libitum
- Acclimation period: 12 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22±3 °C (72°±3 °F)
- Humidity (%): 50% ± 15%
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
inhalation: vapour
Details on exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Inhalation chamber (Harvord Systems Division of Lab Products, Inc. Aberdeen, MD)
- Method of conditioning air: glass beads in a heated glass coloum for vapourization
- Air flow rate: 15 air changes /h
Duration of treatment / exposure:
14 weeks (93 days exposure)
Frequency of treatment:
6 hours per day, 5 days per week
Doses / concentrationsopen allclose all
Dose / conc.:
8 ppm (nominal)
Remarks:
analytical concentration 8 ± 0.3 ppm
Dose / conc.:
16 ppm (nominal)
Remarks:
analytical concentration 15.9 ± 0.6 ppm
Dose / conc.:
32 ppm (nominal)
Remarks:
analytical concentration 32 ± 1.3 ppm
Dose / conc.:
62 ppm (nominal)
Remarks:
analytical concentration 62.2 ± 2.3 ppm
Dose / conc.:
125 ppm (nominal)
Remarks:
analytical concentration 126 ± 5 ppm
No. of animals per sex per dose:
5
Control animals:
yes

Examinations

Tissues and cell types examined:
Peripheral blood
Statistics:
The frequency of micronucleated cells among normochromatic cells was analysed by statistical software package that tested for increasing trend over exposure groups using a one-tailed Cochran-Armitage trend test followed by pairwise comparisons between each exposure group and the control group.

Results and discussion

Test results
Sex:
male/female
Genotoxicity:
negative
Toxicity:
no effects
Vehicle controls validity:
valid
Negative controls validity:
not specified
Positive controls validity:
not specified

Any other information on results incl. tables

Tab. 1 Frequency of Micronuclei in Mouse Peripheral Blood Erythrocytes

Dose (ppm)

Micronucleated Normochromatic Erythrocytes / 1000 cells

 

Male

Female

0

2.80 ± 0.30

2.60 ± 0.29

8

4.60 ± 0.60

2.50 ± 0.61

16

4.10 ± 0.48

2.20 ± 0.25

32

3.30 ± 0.34

3.50 ± 0.57

62

4.00 ± 0.52

3.80 ± 0.60

125

2.60 ± 0.33

2.20 ± 0.25

No significant increase in micronucleated NCEs was observed in males or females and all tested dose groups.

Applicant's summary and conclusion

Conclusions:
The percentage of polychromatic erythrocytes was unaltered, suggesting a lack of bone marrow toxicity.
Executive summary:

In a micronucleus assay with B6C3F1 mice, peripheral blood samples were obtained from 5 male/female animals at the end of a 93 days inhalation toxicity study (6 hours per day, 5 days per week; doses of 0, 8, 16, 32, 62, 125 ppm). No significant increase in micronucleated normochromatic erythrocytes was observed in males or females and all tested dose groups.