1,3-dichlorobut-2-ene

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:

other information

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Adopted according to OECD SIDS (public available peer reviewed source). The original source is not available and has not been reviewed.

Data source

Reference

Reference 1

Reference Type:

secondary source

Title:

1,3-Dichlorobut-2-ene - CAS No: 926-57-8

Author:

OECD SIDS

Year:

2007

Bibliographic source:

SIDS Initial Assessment Report for 22th SIAM, UNEP Publications

Reference 2

Reference Type:

study report

Title:

Unnamed

Year:

1995

Report date:

1995

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OTS 798.5395 (In Vivo Mammalian Cytogenics Tests: Erythrocyte Micronucleus Assay)

GLP compliance:

yes

Type of assay:

micronucleus assay

Test material

Test material information

Constituent 1

Reference substance name:

1,3-dichlorobut-2-ene

EC Number:

213-138-3

EC Name:

1,3-dichlorobut-2-ene

Cas Number:

926-57-8

Molecular formula:

C4H6Cl2

IUPAC Name:

1,3-dichlorobut-2-ene

Details on test material:

- Name of test material (as cited in study report): 1,3-dichlorobut-2-ene
- Analytical purity: 98%

Test animals

Species:

rat

Strain:

other: Crl:CD(R) BR

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: 47 days old
- Housing: rats were housed in suspended, stainless steel wire-mesh cages.

Administration / exposure

Route of administration:

inhalation

Vehicle:

Conditioned, filtered, house-line air was the negative (vehicle) control.

Details on exposure:

TYPE OF INHALATION EXPOSURE: nose only

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
Test atmospheres were generated by metering nitrogen over or through glass impingers containing a reservoir holding 1,3-dichlorobut-2-ene. The nitrogen swept the 1,3-dichlorobut-2-ene vapours into each test chamber via Teflon tubing. The concentration in each chamber was controlled by varying the flow of nitrogen to the impinger. The impingers were kept in a 15ºC bath and were isolated from the rest of the generation system. Filtered, dried dilution air was introduced into each chamber at 40 L/min. For the control chamber, the air flow was 28 L/min.

During exposure, each rat was individually confined in a polycarbonate restrainers placed in a glass and stainless steel 150-L chamber. Only the nose of the animal protruded into the chamber. The positions of the animals within the chambers were randomly rotated daily. The chambers were operated in a one-pass, flow-through mode with air flow rates adequate to provide 16 air changes/hour for the air control chambers. The flow rates provided sufficient oxygen for the test animals and adequate distribution of the test material in the chambers.

At approximately 30-minute intervals, chamber samples of the test atmospheres were drawn and delivered to a gas chromatograph. During exposures, the relative humidity, temperature, and oxygen concentration of each chamber were recorded. An Omega thermocouple was used to measure chamber temperatures, a psychrometer was used to measure relative humidity, and an oxygen monitor was used to measure chamber oxygen.

TEST ATMOSPHERE
At approximately 30-minute intervals, chamber samples of the test atmospheres were drawn and delivered to a gas chromatograph. During exposures, the relative humidity, temperature, and oxygen concentration of each chamber were recorded. An Omega thermocouple was used to measure chamber temperatures, a psychrometer was used to measure relative humidity, and an oxygen monitor was used to measure chamber oxygen.

Duration of treatment / exposure:

2 weeks

Frequency of treatment:

6 hours/day, 5 days/week

Post exposure period:

no data

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 10, 50, 100 ppm
Basis:
nominal conc.

No. of animals per sex per dose:

5

Control animals:

yes

yes, concurrent vehicle

Positive control(s):

The positive control indicator was cyclophosphamide (CP). The rats in the positive control group received CP 24 hours prior to sacrifice.

Examinations

Tissues and cell types examined:

Bone marrow from both femurs.

Details of tissue and slide preparation:

On the day of the last treatment, the animals were sacrificed. The marrow from both femurs of each animal was aspirated and flushed into fetal bovine serum. The marrow button was collected by centrifugation at approximately 200 x g for 5 minutes. Most of the supernatant was removed, and the cells were resuspended in the remaining 1-2 drops of serum. An automatic blood smearing instrument was used to make the bone marrow smears. At least 2 slides per animal were prepared and fixed in absolute methanol. The slides were stained with acridine orange in sodium phosphate buffer.

Method of analysis: Representative slides from each animal were examined in a blind manner using epifluoresence microscopy at a magnification of 630X. A minimum of one thousand polychromatic erythrocytes (PCEs) were scored for the presence of micronuclei. The number of micronucleated normochromatic erythrocytes (NCEs) seen in the optic fields were scored to assure that at least 1000 PCEs were also recorded. In addition, the ratio of polychromatic to normochromatic erythrocytes (NCEs) was determined.

Evaluation criteria:

No data

Statistics:

Data for the percent micronucleated PCEs and proportion of PCEs among total erythrocytes were transformed prior to analysis using the arcsine square-root function. Weight gain data were not transformed. Data for each sex were analyzed separately by a one-way Analysis of Variance (ANOVA). The positive indicator group was not included in the analysis for effects of the test substance. All analyses were one-tailed.

Results and discussion

Test results

Sex:

male/female

Genotoxicity:

negative

Toxicity:

yes

Remarks:

A significant decrease in body weight gain occurred in all groups of 1,3-dichlorobut-2-ene exposed male animals after 10 days of exposure.

Vehicle controls validity:

valid

Negative controls validity:

not examined

Positive controls validity:

valid

Any other information on results incl. tables

Analytical analysis of the concentrations: the test chamber concentrations were within normal range and delivered the approximate doses of 0, 10, 50, and 99 ppm 1,3-dichlorobut-2-ene.

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information): negative