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Toxicological information

Genetic toxicity: in vivo

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Administrative data

Endpoint:
in vivo mammalian germ cell study: cytogenicity / chromosome aberration
Remarks:
Type of genotoxicity: chromosome aberration
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: comparable to guideline study conducted in compliance with GLP regulations

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1987
Report date:
1980

Materials and methods

Principles of method if other than guideline:
Following exposure of male rodents to varying concentrations of the test article by a route reflecting the mode of human environmental exposure,
bone marrow cells arrested in C-metaphase are examined microscopically for chromosome aberrations, numerical and structural. The types of damage expected duo to the action of mutagenic compounds are chromatid or chromosomal breaks and structural rearrangements, although in some
advanced cases, clones of aberrant cells may indicate a change from the normal diploid number.
GLP compliance:
yes
Type of assay:
chromosome aberration assay

Test material

Constituent 1
Chemical structure
Reference substance name:
2-ethylhexan-1-ol
EC Number:
203-234-3
EC Name:
2-ethylhexan-1-ol
Cas Number:
104-76-7
Molecular formula:
C8H18O
IUPAC Name:
2-ethylhexan-1-ol
Details on test material:
- Name of test material (as cited in study report): R-1213/T1640
- Physical state: liquid
- Analytical purity: 99.7%
- Storage condition of test material: room temperature in the dark

Test animals

Species:
rat
Strain:
Fischer 344
Sex:
male
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River Breeding Farms
- Age at study initiation: 4-6 weeks old
- Weight at study initiation: 115-150 g
- Assigned to test groups randomly: [yes, under following basis: random, not further specified ]
- Housing: 3-4 per cage during acclimation period, individually thereafter
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 10-14 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 23 +-3 °C
- Humidity (%): 50 +- 20 %
- Air changes (per hr):
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
- Vehicle(s)/solvent(s) used: [corn oil]
- Justification for choice of solvent/vehicle: none given
- Concentration of test material in vehicle: 0.02, 0.07 and 0.21 ml/kg of the test material (amount of vehicle not stated)
- Amount of vehicle (if gavage or dermal): 5 ml/kg
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:
The test article-carrier mixture was formulated such that each animal received 5 ml/kg body weight/day . The rats were weighed and dosed by gavage for five consecutive days with the appropriate concentration of the test article or vehicle (carrier) control.
Duration of treatment / exposure:
5 days
Frequency of treatment:
once daily
Post exposure period:
none
Doses / concentrations
Remarks:
Doses / Concentrations:
0.02, 0.07, and 0.21 ml/kg bw/day (corresponding to approximately 16.6, 58.1, and 174.3 mg/kg bw/day)
Basis:
nominal conc.
No. of animals per sex per dose:
5
Control animals:
yes, concurrent vehicle
Positive control(s):
triethylenemelamine
- Justification for choice of positive control(s): none given
- Route of administration: single intraperitoneal injection
- Doses / concentrations: 0.5 mg/kg

Examinations

Tissues and cell types examined:
A minimum of 50 metaphase spreads from each animal was examined and scored for chromatid and chromosomal gaps and
breaks, fragmentation, structural rearrangements, and ploidy.
Details of tissue and slide preparation:
CRITERIA FOR DOSE SELECTION:
The doses were selected on the basis of the result of the determination of the LD50 in rats.

TREATMENT AND SAMPLING TIMES ( in addition to information in specific fields):
The test article-carrier mixture was formulated such that each animal received 5 ml/kg body weight/day . The rats were weighed and dosed by gavage for five consecutive days with the appropriate concentration of the test article or vehicle (carrier) control. The positive control, TEM, was injected
intraperitoneally (IP) as a single-treatment one day prior to sacrifice at a dose level of 0.5 mg/kg.

DETAILS OF SLIDE PREPARATION:
All rats were given colchicina at 4 mg/kg IP 2 hours prior to sacrifice. The rats were sacrificed by carbon dioxide asphyxiation, the femurs were
removed and the marrow was flushed into HBSS. After centrifugation at 800-1000 rpm for 8-10 minutes, the cells were treated with 0.075 M KCl for
20-30 min at 37+-2 °C. The cells were again centrifuged and washed twice with 5 ml Carnoy's fixative. The cells were resuspended in 5 ml Carnoy's
fixative and treated overnight (16-20 hr) at 4 +- 2°C . The cells were centrifuged at 800-1000 rpm for 8-10 min and the cell pellet was resuspended
to opalescence in fresh Carñoy's fixative. Two to five slides were prepared from each animal. Slides were stained with Giemsa and permanently
mounted.

METHOD OF ANALYSIS:
A minimum of 50 metaphase spreads from each animal was examined and scored for chromatid and chromosomal gaps and breaks, fragmentation,
structural rearrangements, and ploidy. The mitotic index was recorded for each rat as the number of cells in mitosis/100 cells observed.

Evaluation criteria:
The percentage of cells in the negative control group demonstrating chromosome and chromatid break's and gaps must be less than or equal to 4% of the total cells analyzed. The percentage of cells demonstrating aberrations of any type must not exceed 10% in the negative control group. The
difference between the percentage of calls with aberrations in the positive control group and the negative control group must be at least 15%. The
number of cells with aberrations in the positive control group must also be statistically increased (p<=0.05) relative to the negative control using t-test statistics.
.
Statistics:
Chi-square analysis using a 2x2 contingency table was used to ascertain significant relationships between the number of cells with aberrations in the
treatment group relative to the negative control. The t-test was used to compare pairwise the number of aberrations per cell of the treatment group with that of the negative control.

Results and discussion

Test results
Sex:
male
Genotoxicity:
negative
Toxicity:
no effects
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
valid

Any other information on results incl. tables

There was no change in ploidy in the treatment groups relative to the negative 
controls. 2 -Ethylhexan-1 -ol was not a mitotic inhibitor when compared to the 
negative controls.
The percentage-of cells with aberrations for all treatment groups was not 
statistically (p>0.05) increased relative to the negative control group using 
Chi-square statistics.
The total aberrations per cell for all treatment groups were not significantly 
p>0.05) increased relative to the negative control group using t-test statistics.


Percentage of cells with aberrations:
-------------------------------------

Treatment Gaps Breaks Rearrangements SDC Total
-----------------------------------------------------------
negative c. 0.8 0 0 0 0
positive c. 8.8 7.2 2.0 17.2 26.4
TS 0.21 3.6 0.4 0 0 0.4
TS 0.07 2.8 0.4 0 0 0.4
TS 0.02 4.8 0 0 0 0
-----------------------------------------------------------
Treatment dose (TS): ml/kg/day
SDC: severly damaged cells, i.e. cells having more than 10 aberrations

Severity of damage as aberrations per cell:
-------------------------------------------

Treatment Total Total Total Total Aberrations
Gaps Breaks Rearrange- SDC per cell
ments
-----------------------------------------------------------
negative c. 2 0 0 0 0
positive c. 71 54 19 430 2.01
TS 0.21 13 1 0 0 <0.01
TS 0.07 13 1 0 0 <0.01
TS 0.02 15 0 0 0 0
-----------------------------------------------------------
Treatment dose (TS): ml/kg/day
Total SDC: cells having more than 10 aberrations were counted as 10

Applicant's summary and conclusion

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