Butyl 2,3-epoxypropyl ether

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / bone marrow chromosome aberration

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1979

Report date:

1979

Materials and methods

Principles of method if other than guideline:

To evaluate the in vivo genetic toxicity of the test substance a Bone Marrow Cytogenetics study was performed in the rat at levels of 31.3, 104.2 and 312.5 mg/kg bw per day.

GLP compliance:

no

Type of assay:

other: Mammalian Bone Marrow Chromosome Aberration Test

Test material

Test material information

Constituent 1

Reference substance name:

Butyl 2,3-epoxypropyl ether

EC Number:

219-376-4

EC Name:

Butyl 2,3-epoxypropyl ether

Cas Number:

2426-08-6

Molecular formula:

C7H14O2

IUPAC Name:

2-(butoxymethyl)oxirane

Test material form:

liquid

Specific details on test material used for the study:

Test material is indicated as R0065 in the study report.

Test animals

Species:

rat

Strain:

Sprague-Dawley

Details on species / strain selection:

CR-1

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories Inc., Wilmington, Massachusetts
- Age at study initiation: sexually mature
- Weight at study initiation: 150-200 gram
- Assigned to test groups randomly: yes
- Housing: individually in hanging wire mesh cages
- Diet: Purina Laboratory Chow ad libitum
- Water: via water bottles ad libitum
- Acclimation period: one week

Administration / exposure

Route of administration:

intraperitoneal

Vehicle:

distilled water

Details on exposure:

The test material was dissolved in an appropriate vehicle (distilled water) and was made up fresh each dose day. The entire study was performed using a single batch of the chemical.

Duration of treatment / exposure:

5 days

Frequency of treatment:

daily

Post exposure period:

On Day 6, all animals received an intraperitoneal injection of colchicine (2.0 mg/kg body weight) to inhibit mitosis in dividing cells. Approximately two to four hours after injection of colchicine, the animals were sacrificed using carbon-dioxide (C02) anaesthesia followed by cervical dislocation.

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

31.3 mg/kg bw/day (actual dose received)

Doses / concentrations 2

Dose / conc.:

104.2 mg/kg bw/day (actual dose received)

Doses / concentrations 3

Dose / conc.:

312.5 mg/kg bw/day (actual dose received)

No. of animals per sex per dose:

5

Control animals:

yes, concurrent vehicle

Positive control(s):

Triethylene melamine (TEM)
- Route of administration: intraperitoneal injection
- Doses / concentrations: Single injection at Day 5, 0.04 mg/kg (Dose volume 5 mL/kg)

Examinations

Tissues and cell types examined:

Bone marrow cells collected from both femurs of each animal.
Fifty cells in the metaphase state of mitosis were examined from each rat that provided analysable cells. The slides were scanned with a low power objective (10x) to find metaphases and, once found, the metaphases were analysed via high power oil immersion lens (100x).

Details of tissue and slide preparation:

Immediately following sacrifice, bone marrow cells were collected from both femurs of each animal by aspiration into a 12 mL syringe filled with 5 mL of pre-warmed (37 °C) Hank's balanced salt solution at pH 7.4. The aspirate was transferred to a centrifuge tube and centrifuged for five minutes at 100 x g. The supernatant was decanted and 3.0 mL of 0.075M KCl was added to each tube. After standing at room temperature for 25 minutes, each tube was centrifuged for five minutes at 100 x g. The supernatant was decanted and 5 mL of freshly prepared Carnoy's Fixative (3:1, methanol : glacial acetic acid v:v) was added to each tube. The tubes stood at room temperature for 20 minutes and were centrifuged for five minutes at 100 x g. The supernatant was discarded and the cells were re-suspended in 5 mL of fresh fixative. Each tube was sealed and refrigerated overnight (4 °C). The next day each tube was centrifuged at 100 x g for five minutes. The supernatant was decanted and the cells were suspended in 2-3 mL fresh Carnoy's Fixative. Three drops of this final cell suspension were dropped onto pre-cleaned glass microscope slides which were then gently blown dry. Three slides were made for each animal. Each slide was identified with the animal's number.

Evaluation criteria:

The metaphases were observed for the cytogenetic abnormalities, mitotic index (number of cells undergoing mitosis per 100 cells counted), and modal number (number of chromosomes in each metaphase). Chromosomal aberrations were classified into one of four basic groups: (1) chromatid and (2) chromosome breaks; (3) markers which involve dicentrics, exchanges, rings and other miscellaneous configurations and (4) severely damaged cells.

Statistics:

The mean changes in body weights, the mean modal number (number of chromosomes in each metaphase), and the mean mitotic index (number of cells undergoing mitosis per 100 cells counted) were analysed using Bartlett's test for equality of variance (Bartlett, 1937) and the one-way classification of analysis of variance (ANOVA) (Snedecor and Cochran, 1967). If significant results were obtained from both analyses, group mean values were compared using the multiple comparison procedure of Games and Howell (Games and Howell, 1976). If only the ANOVA were significant, Scheffe's multiple comparison procedure (Scheffe, 1953) was used to compare group means. The aberrant cells and the categories of chromatid breaks, chromosome breaks, markers, and severely damaged cells were statistically analysed either by Wilcoxon`s nonparametric comparison of group means (Snedecor and Cochran, 1957) or by chi-square analysis (Snedecor and Cochran, 1967). Regression analyses (Draper and Smith, 1966) were performed on all data when significant responses were observed in the treated groups.

Results and discussion

Test results

Key result

Sex:

male/female

Genotoxicity:

positive

Toxicity:

no effects

Vehicle controls validity:

valid

Negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

Clinical observations and mortality:
One animal from the high-dose group died. There were no observable gross pathological findings. Statistical analysis of the mean body weight increases revealed no significant differences among any of the groups.
Analysis of marker aberrations resulted in a significant elevated mid-dose group. The low- and high-dose groups were elevated with respect to the incidence of severely damaged cells. The percent of aberrant cells (total number of aberrant cells per animal) was significantly increased among all treated groups when compared to the negative control. Therefore, under the conditions of this study, the test substance administered intraperitoneally for five consecutive days at doses as low as 31.3 mg/kg bw/day resulted in structural chromosomal aberrations in the rat bone marrow cells at all levels.