3,4-dihydro-2-methoxy-2H-pyran

Genetic toxicity: in vivo

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:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1993

Report date:

1993

Reference 2

Reference Type:

secondary source

Title:

3,4-Dihydro-2-methoxy-2H-pyran (CAS No. 4454-05-1)

Author:

OECD

Year:

2003

Bibliographic source:

cited in OECD SIDS 3,4-Dihydro-2-methoxy-2H-pyran for SIAM 16, 27-30 May 2003, Paris, France.

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

Deviations:

no

GLP compliance:

yes

Remarks:

(BASF AG, Department of Toxicology)

Type of assay:

micronucleus assay

Test material

Test material information

Constituent 1

Reference substance name:

3,4-dihydro-2-methoxy-2H-pyran

EC Number:

224-698-3

EC Name:

3,4-dihydro-2-methoxy-2H-pyran

Cas Number:

4454-05-1

Molecular formula:

C6H10O2

IUPAC Name:

2-methoxy-3,4-dihydro-2H-pyran

Constituent 2

Reference substance name:

Reference substance 001

Details on test material:

- Name of test material (as cited in study report): 2-Methoxy-2,3-dihydro-4H-pyran
- Physical state: colorless liquid
- Analytical purity: 99.9%
- Lot/batch No.: Tank 57
- Storage condition of test material: Refrigerator (protected from light, N2 conditions)

Test animals

Species:

mouse

Strain:

NMRI

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River GmbH, WIGA, Sulzfeld
- Mean weight at study initiation: 26 g
- Housing: 5 per cage
- Diet (e.g. ad libitum): Standardized pelleted feed (Kliba Haltungsdiet, Kaiseraugst, Switzerland)
- Water: ad libitum
- Acclimation period: 1 week


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-24
- Humidity (%): 30-70
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

- Vehicle(s)/solvent(s) used: olive oil
- Concentration of test material in vehicle (%): 2.5, 5.0 and 10.0
- Amount of vehicle (if gavage or dermal): 10 ml/kg bw

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: The test substance, methoxydihydropyran (MDP) was dissolved in olive oil at concentration of 2.5, 5.0 and 10% and applied at dose levels of 250, 500 and 1000 mg/kg bw. All test substance formulations were prepared immediately before administration. The samples were kept at room temperature until the treatment of the last animal (approximately 1 hour) and then deep-frozen until they were determined analytically. The determination of the concentration in the solvent was carried out by means of capillary GC. The mean analytical measurements of the theoretical doses of 25, 50 and 100 mg/ml were 27.1, 54.7 and 109.2 mg/l, respectively.

Duration of treatment / exposure:

single dose

Frequency of treatment:

once

Doses / concentrations

Remarks:

Doses / Concentrations:
250, 500, 1000 mg/kg bw
Basis:
nominal conc.

No. of animals per sex per dose:

5 per sex, dose and sacrifice interval

Control animals:

yes, concurrent vehicle

Positive control(s):

Cyclophosphamide 20 mg/kg bw in 5 animals (2 males and 3 females)
Vincristine 0.15 mg/kg bw in 5 animals (3 males and 2 females)

Examinations

Tissues and cell types examined:

Bone marrow

Details of tissue and slide preparation:

CRITERIA FOR DOSE SELECTION: Dose selection was based on the pretest for the determination of the acute oral toxicity.


TREATMENT AND SAMPLING TIMES: Femural bone marrow was prepared 24 hr post dosing in all dose groups, and also at 16 hr and 48 hr in the 1000 mg/kg dose group.


DETAILS OF SLIDE PREPARATION: The bone marrow was prepared according to the method described by Schmid, W. The micronucleus test for cytogenetic analysis. In: Hollaender, A. (ed), Chemical Mutagens, Principles and Methods for their Detection, Volume 4, Plenum Press, New York (1976).

Evaluation criteria:

Generally, 1000 polychromatic erythrocytes per animal are evaluated for the following parameters: no. of polychromatic erythrocytes with/without micronuclei and calculation of clastogenic index, no. of normochromatic erythrocytes with/without micronuclei, calculation of ratio polychromatic/normochromatic erythrocytes, no. of small (d<1/4) and large (d>1/4) micronuclei.

Statistics:

A statistical evaluation was not necessary to perform as the number of polychromatic micronucleated erythrocytes after test substance treatment was nearly the range of the actual control value and within the historical values.

Results and discussion

Test results

Sex:

male/female

Genotoxicity:

negative

Toxicity:

yes

Remarks:

signs of intoxication were present in all dose groups. No mortality was observed. See free text.

Vehicle controls validity:

valid

Positive controls validity:

valid

Additional information on results:

RESULTS OF RANGE-FINDING STUDY
In the pretest, deaths were observed down to a dose of 1210 mg/kg bw. A dose of 1000 mg/kg bw was tolerated by all animals but led to signs of toxicity such as irregular respiration, piloerection, staggering and squatting posture. In few cases gasping, abdominal position and closed eyelids were additionally observed. Therefore, a dose of 1000 mg/kg bw was selected as the highest dose in the present cytogenetic study. 500 and 250 mg/kg bw were administered as further doses.

RESULTS OF DEFINITIVE STUDY
- Clinical signs: none after vehicle only nor after positive control substances. At 250 mg/kg bw: irregular respiration, piloerection 15-60 min after dosing; at 500 mg/kg bw: additionally staggering, squatting posture after 15-60 min; at 1000 mg/kg bw: additionally gasping, abdominal position after 0.5 -4 hr.
- Induction of micronuclei (for Micronucleus assay): No increase in the number of polychromatic erythrocytes containing either small or large micronuclei was observed. The rate of micronuclei was always in the same range as that of the negative control in all dose groups and at all sacrifice intervals.
- Ratio of PCE/NCE (for Micronucleus assay): No inhibition of erythropoiesis determined from the ratio of polychromatic to normochromatic erythrocytes was detected.

Any other information on results incl. tables

Mean cells with micronuclei at 24 hr after dosing, expressed as % in poly- (=pe) and normochromatic (=ne) erythrocytes:
Solvent control:             pe=   1.5          ne= 0.74
cyclophosphamide:       pe= 12.4          ne= 1.33
vincristine:                     pe= 139.0        ne= 3.09
MDP, 250 mg/kg:         pe=   2.2          ne= 1.17
MDP, 500 mg/kg:         pe=   1.9          ne= 1.80
MDP, 1000 mg/kg:      pe=   2.3          ne= 1.58

Applicant's summary and conclusion

Executive summary:

This study was conducted according to OECD guideline with GLP and is reliable without restrictions. Five mice per sex, dose and sacrifice intervals were administered with single oral dose of the test substance at concentrations of 250, 500 and 1000 mg/kg bw. The animals were sacrificed and the bone marrow was prepared 16, 24 and 48 hours after administration in the highest dose group of the 1000 mg/kg bw. In the test groups of 500 mg/kg and 250 mg/kg bw, in the negative and positive control groups, the 24-hour sacrifice intervals were only investigated. No increase in the number of polychromatic erythrocytes containing either small or large micronuclei was observed. No inhibition of erythropoiesis determined from the ratio of polychromatic to normochromatic erythrocytes was detected.

Conclusion: Under the experimental conditions chosen here, the test substance does not have any chromosome-damaging (clastogenic) effect, and there were no indications of any impairment of chromosome distribution in the course of mitosis.