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Toxicological information

Genetic toxicity: in vivo

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Administrative data

Endpoint:
in vivo mammalian somatic cell study: cytogenicity / bone marrow chromosome aberration
Remarks:
Type of genotoxicity: chromosome aberration
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1990
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: This study is classified as reliable without restriction because it closely followed OECD Guideline 475.
Cross-reference
Reason / purpose:
reference to same study

Data source

Reference
Reference Type:
publication
Title:
Cytogenetic studies on commercial hexane solvent
Author:
Daughtrey, W., Putman, D., Duffy, J., Soiefer, A., Kirwin, C,, Curcio, L,, Keenan, T
Year:
1994
Bibliographic source:
Journal of Applied Toxicology. May-Jun; 14(3):161-5

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 475 (Mammalian Bone Marrow Chromosome Aberration Test)
Deviations:
yes
Remarks:
In order to test substance as a vapor, animals were exposed via nose-only inhalation.
GLP compliance:
yes (incl. certificate)
Type of assay:
other: cytogenetics assay

Test material

Reference
Name:
Unnamed
Type:
Constituent

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Harlan Sprague Dawley, Inc., Frederick, MD
- Age at study initiation: 6-8 weeks
- Weight at study initiation: 228-266 g males, 153-188 g females
- Assigned to test groups randomly: assigned using body weight randomization program
- Housing: singly in plastic cages, identified by ear tags
- Diet (e.g. ad libitum): certified laboratory rodent chow, ad libitum
- Water (e.g. ad libitum): tap water ad libitum
- Acclimation period: 10 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 72 degree F
- Humidity (%): 40-70
- Photoperiod (hrs dark / hrs light): 12 hrs light/12 hrs dark

Administration / exposure

Route of administration:
inhalation: vapour
Details on exposure:
TYPE OF INHALATION EXPOSURE: nose only


GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: 360 ml polycarbonate chamber
- Method of holding animals in test chamber: Polycarbonate tubes were used to restrain the animals. Only the nose of the animals protruded into the chambers. A soft sponge was used as a plunger to hold the animals in place.
- Source and rate of air: filtered outside air
- Method of conditioning air: A Gilson peristaltic pump was used to meter test liquid in sealed resevoirs to vaporization flasks immersed in 57 degree C water. Air was passed through the flasks, then through teflon tubing to the exposure chamber. A calibrated rotameter was used to dilute the air to the appropriate concentration.
- Temperature, humidity, pressure in air chamber: monitored every 30 min.
- Air flow rate: monitored every 30 min.


TEST ATMOSPHERE
- Brief description of analytical method used: GC
- Samples taken from breathing zone: yes
Duration of treatment / exposure:
6 hrs per day
Frequency of treatment:
5 days
Post exposure period:
1 or 19 hrs after end of exposure
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 900, 3000, 9000 ppm (0, 3168, 10560, 31680 mg/m3)
Basis:
nominal conc.
No. of animals per sex per dose:
5 male and 5 female per dose
Control animals:
yes, sham-exposed
Positive control(s):
triethylenemelamine
- Route of administration: intraperitoneal injection
- Doses / concentrations: 0.5 mg/kg

Examinations

Tissues and cell types examined:
bone marrow
Details of tissue and slide preparation:
TREATMENT AND SAMPLING TIMES ( in addition to information in specific fields):
Colchicine was administered two hours prior to sacrifice to arrest cell division at metaphase. Animals were sacrificed by carbon dioxide asphyxiation. Bone marrow cells were removed from the femur by aspiration into HBSS. Cells were mixed well and kept in an ice bath until all samples were collected. After centrifuging for 10 min, the supernatent was discarded, and the cells resuspended in 5 ml 0.075 M KCl at 37 degree C. After incubating for 10 min, cells were again centrifuged and resuspended in fixative. This was repeated with fresh fixative.

DETAILS OF SLIDE PREPARATION:
Cells were again centrifuged for 10 min, the supernantant decanted, and the cells resuspended in 1 ml of fixative. Two drops were placed on a cold wet glass slide, and allowed to air dry. Three slides were prepared per animal. Slides were stained with 4% Giemsa.

METHOD OF ANALYSIS:
50 metaphase cells containing approx. 40 centromeres were scored if possible.

OTHER:
Evaluation criteria:
In order for the test to be valid, there must be no more than 4% cells demonstrating aberrations in the negative control group. Positive control must be statistically increased over untreated controls (p<=0.05, Fisher's exact test). A positive result is a percentage of cells with aberrations which was statistically increased over untreated controls (p<=0.05, Fisher's exact test).
Statistics:
Fisher's exact test was used to determine statistical significance. Cochran-Armitage test was used to test dose-responsiveness.

Results and discussion

Test results
Sex:
male/female
Genotoxicity:
negative
Toxicity:
no effects
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
There was a decrease in body weight observed after the last exposure. This reduction is typical for nose-only exposure, and is considered to be due to restraint. There was no statistically significant increase in aberrations in the exposure groups.

Any other information on results incl. tables

Chromosomal Damage in Rat Bone Marrow - Male         

Dose (ppm)

Time Evaluated (hrs)

Cells with Aberrations (%)

Mean Aberrations per Cell per Animal

0

6

0.0

0.000 ± 0.000

0

24

0.0

0.000 ± 0.000

876

6

0.4

0.004 ± 0.009

876

24

0.0

0.000 ± 0.000

3249

6

0.0

0.000 ± 0.000

3249

24

0.4

0.004 ± 0.009

8715

6

0.8

0.008 ± 0.018

8715

24

0.4

0.004 ± 0.009

Positive Control

6

14.4

0.696 ± 0.121

Chromosomal Damage in Rat Bone Marrow - Female

Dose (ppm)

Time Evaluated (hrs)

Cells with Aberrations (%)

Mean Aberrations per Cell per Animal

0

6

0.8

0.008 ± 0.011

0

24

0.0

0.000 ± 0.000

876

6

0.4

0.004 ± 0.009

876

24

0.4

0.004 ± 0.009

3249

6

0.4

0.004 ± 0.009

3249

24

0.0

0.000 ± 0.000

8715

6

0.4

0.004 ± 0.009

8715

24

0.4

0.004 ± 0.009

Positive Control

6

20.8

0.900 ± 0.477

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): negative
The test substance is not mutagenic.
Executive summary:

This study determined the effect of inhalation exposure of commercial hexane on rat bone marrow. Groups of 5 male and 5 female rats were exposed to 0, 900, 3000, and 9000 ppm of test substance vapor for 6 hrs/day for 5 days. 0.5 mg/kg triethylenemelamine was used as a positive control substance. Animals were sacrificed 3 or 21 hrs after exposure, and the bone marrow from their femurs examined for cell aberrations. There was no statistically significant increase in cell aberrations in any treatment group. The test substance is not mutagenic.