Condensates (petroleum), vacuum tower

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / bone marrow 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

Study period:

1984-05-16 to 1985-05-16

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: This study is classified as reliable without restriction because the study was conducted according or similar to OECD 475.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1985

Report date:

1985

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 475 (Mammalian Bone Marrow Chromosome Aberration Test)

GLP compliance:

yes

Type of assay:

chromosome aberration assay

Test material

Test material information

Constituent 1

Reference substance name:

Straight run middle distillate (CAS# 64741-44-2)

IUPAC Name:

Straight run middle distillate (CAS# 64741-44-2)

Details on test material:

- Name of test material (as cited in study report): API 83-11 (Microbiological Associates, Inc. code # T2419)
- Physical state: Clear, colourless, non-viscous liquid
- Substance type: Gas oil
- Stability under test conditions: Not determined
- Storage condition of test material: Stored at room temperature in the dark

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratory; Kingston, New York
- Age at study initiation: 6 to 8 weeks old
- Weight at study initiation: At randomisation, males were 235 to 289 grams and females were 160 to 199 grams
- Assigned to test groups randomly: Yes
- Fasting period before study: Not reported
- Housing: Three to four per cage during quarantine and singly thereafter in plastic cages with wire lids
- Diet (e.g. ad libitum): Ad libitum
- Water (e.g. ad libitum): Ad libitum
- Acclimation period: 10 to 14 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 23.3±3°C
- Humidity (%): 50±20%
- Air changes (per hr): Not reported
- Photoperiod (hrs dark / hrs light): 12 hours light/dark

IN-LIFE DATES: 1984-05-16 to 1985-05-16

Administration / exposure

Route of administration:

intraperitoneal

Vehicle:

Corn oil, lot B1121 obtained from Eastman Chemical company, Rochester, New York

Details on exposure:

Intraperitoneal injection

Duration of treatment / exposure:

Animals sacrificed at 6, 24, and 48 hours after injection

Frequency of treatment:

Single injection

Post exposure period:

2 to 4 hours post colchicine injection to arrest cells in metaphase

Doses / concentrations

Remarks:

Doses / Concentrations:
300, 1000, or 3000 mg/kg
Basis:
nominal conc.

No. of animals per sex per dose:

5 animals per sex per dose per timepoint

Control animals:

yes, concurrent vehicle

Positive control(s):

0.5 mg/kg of triethylenemelamine by intraperitoneal injection

Examinations

Tissues and cell types examined:

Bone marrow cells extracted from the femur

Details of tissue and slide preparation:

CRITERIA FOR DOSE SELECTION: A confirmatory test was conducted by exposing 4 male and female rats to 3.0 g/Kg API 83-11 for 24 hours. Based on mortality observed in 1 of the 4 male rats, 0.3, 1.0, and 3.0 g/Kg were selected for the study.

TREATMENT AND SAMPLING TIMES: Bone marrow cells harvested at 6, 24, and 48 hours

DETAILS OF SLIDE PREPARATION:
Cells were centrifuged at approximately 100 x g for 10 minutes, the supernatant fluid was decanted, and the cells were resuspended to opalescence in about 1 millilitre fresh fixative. Two to three drops of cell suspension were dropped onto glass slide and allowed to air dry. At least three slides were prepared from each animal. Dry slides were stained with 4% Giemsa stain and mounted. Stained slides were coded and were scored without regard to treatment group. Where possible, a minimum of 50 metaphase cells from each animal were examined and scored for chromatid and chromosome gaps and breaks, fragments, structural rearrangements, and ploidy (1 to 3). The XY coordinates for each cell with chromosomal aberrations was
recorded using a calibrated microscope stage. The ratio of the number of cells in mitosis per 500 cells counted x 100 is defined as the mitotic index.

METHOD OF ANALYSIS:
Stained slides were coded and scored without regard to the treatment group. A minimum of 50 metaphase cells from each animal were examined and scored for chromatid and chromosome gaps and breaks, fragments, structural arrangements, and ploidy. The XY co-ordinates of each cell with chromosome aberrations was recorded using a calibrated microscope stage.

Evaluation criteria:

The test article is considered to induce a positive response when the percentage of cells with aberrations in any treatment group is significantly increased (p=0.05) relative to the vehicle control using Chi-square analysis and the number of aberrations per cell is also significantly increased (p=0.05) relative to the vehicle control using t-test statistics. Additionally, the percentage of cells in the vehicle control group exhibiting aberrations of any type (except gaps) should not exceed 4% and the percentage of cells in the positive control group exhibiting aberrations must be significantly higher (p = 0.05) than the vehicle control group.

Statistics:

Chi-square analysis using a 2 x 2 contingency table was used to ascertain significant differences between the number of cells with aberrations in the treatment and control groups. The severity of damage within the cells is reported as the number of aberrations per cell for each treatment group. Chromatid and chromosome gaps are presented in the data but are not included in the average number of aberrations per cell. The t-test was used to compare pair-wise the number of aberrations per cell of each treatment group with that of the vehicle control. Each comparison was considered to be between two independent, random samples of unequal variance and a significant increase in the treatment mean relative to the vehicle control (one-sided) was sought.

Results and discussion

Test results

Sex:

male/female

Genotoxicity:

negative

Toxicity:

no effects

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

RESULTS OF RANGE-FINDING STUDY
- Dose range: 3.0 g/Kg single intraperitoneal injection
- Clinical signs of toxicity in test animals: mortality observed in 1 of 4 male rats
- Evidence of cytotoxicity in tissue analyzed: Not reported
- Rationale for exposure: Not reported
- Harvest times: 24 hours

RESULTS OF DEFINITIVE STUDY
- Types of structural aberrations for significant dose levels (for Cytogenetic or SCE assay): a small number of gaps and breaks were observed at all dose levels tested
- Statistical evaluation: At 24 hours, the percentage of chromosome aberrations was 0 (vehicle control); 0.2 (API 83-11 - 3.0 g/Kg); 0.2 (API 83-11 - 1.0 g/Kg); 0 (API 83-11 - 0.3 g/Kg); and 35.4 (positive control). The number of aberrations per cell at 24 hours was 0 (vehicle control); 0.004 (API 83-11 - 3.0 g/Kg); 0.002 (API 83-11 - 1.0 g/Kg); 0 (API 83-11 - 0.3 g/Kg); and 2.358 (positive control)

Any other information on results incl. tables

No clinical signs of toxicity were observed although male rats receiving 3000 mg/kg experienced 4% weight loss at 24 hours after test substance administration and female rats receiving 3000 mg/kg experienced 2% weight loss at 48 hours.

There was no change in ploidy, effect on mitotic index, or cell aberrations in response to treatment with API 83-11. Treatment with TEM caused the appropriate positive response.

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information): negative
Under the conditions of the study, straight-run middle distillate did not induce chromosome aberrations in bone marrow cells of male or female rats.

Executive summary:

Justification for Read Across

Compositional and physico-chemical data show that Straight-Run Gas Oils are very similar to VGOs/HGOs/Distillate Fuels. It is considered appropriate, therefore, to read across from the Straight-Run Gas Oil data to VGOs/HGOs/Distillate Fuels.

In a Sprague-Dawley rat bone marrow micronucleus assay, male and female rats (5/sex/dose/timepoint) were treated with a single intraperitoneal dose of straight-run middle distillate at dose levels of 0, 300, 1000 or 3000 mg/kg bw. Bone marrow cells were harvested at 6, 24, and 48 hours post-treatment. The vehicle was corn oil.

 

There were no clinical signs of toxicity during the study, although male rats receiving 3000 mg/kg experienced 4% weight-loss at 24 hours after test substance administration, and female rats receiving 3000 mg/kg experienced 2% weight-loss at 48 hours. The positive control TEM induced the appropriate response. There was no evidence of increased incidence of chromatid or chromosome gaps and breaks, fragments, structural rearrangements, or ploidy in bone marrow cells treated with straight-run middle distillate in comparison to controls.

This study received a Klimisch score of 1 and is classified as reliable without restriction because the study was conducted according or similar to OECD 475.