Registration Dossier

Administrative data

Endpoint:
in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus
Remarks:
Type of genotoxicity: chromosome aberration
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Study period:
No data reported.
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: This study is classified as reliable without restriction because it was conducted according to or similar to guideline study OECD TG 474 without exceptions.

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1999

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)
Deviations:
yes
Remarks:
lower number of animals/group
GLP compliance:
not specified
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Test material form:
other: oily liquid
Details on test material:
- Test substance: Unrefined/acid treated oils
- Unrefined lubricating oil (ULO) feedstock derived from a naphthenic crude oil: CAS# 64741-53-3

Physical state: Olily liquid

Test animals

Species:
mouse
Strain:
CD-1
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Canada (Quebec, Canada)
- Age at study initiation: 6 to 9 weeks old
- Weight at study initiation: 17 to 35 grams
- Assigned to test groups randomly: not reported
- Fasting period before study: not reported
- Housing: singly housed in wire mesh cages
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: quarantine for 17 days


ENVIRONMENTAL CONDITIONS: not reported


IN-LIFE DATES: not reported

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
A number of separate micronucleus studies were conducted including:
Unrefined lubricating oil neat via oral gavage

Details on exposure:
micronucleus studies were conducted based on a range-finding experiment.
Duration of treatment / exposure:
Experiment 3: Cells harvested 24 hours after last administration of test substance
Frequency of treatment:
Experiment 3: two consecutive daily doses
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 1.25, 2.5, 5.0 g/kg
Basis:
other: experiment 3
No. of animals per sex per dose:

Experiment 3: 2/sex/dose

Control animals:
yes, concurrent vehicle
Positive control(s):
Experiment 3: 7,12-dimethylbenzanthracene (DMBA), 0.15 g/kg

Examinations

Tissues and cell types examined:
Bone marrow cells
Details of tissue and slide preparation:
Both femurs were removed from each treated mouse, and the proximal ends were cut to expose the bone marrow which was then aspirated with foetal bovine serum into a centrifuge tube. The cells were collected by centrifugation, and slides were prepared. After fixation in methanol, the slides were stained with acridine orange for approximately 1 to 2 minutes and evaluated at 400X magnification by fluorescence microscopy. A total of 1000 erythrocytes were counted from each animal, and the total number of polychromatic (PCE) and normochromatic (NCE) erythrocytes were tabulated. One thousand PCEs were evaluated for the presence of micronuclei.
Statistics:
Means and standard deviations were calculated. Test of equality of group means by standard one way analysis of variance at each time period was calculated. When ANOVA was significant, comparisons of carrier control to dosed group means were made according to Duncan's Multiple Range Test. A standard regression analysis was performed to test for a dose response. Residuals from the ANOVA were analyzed for normality by Wilk’s Criterion. The residuals were normally distributed (values were greater than 0.01 level of significance) in more than 75% of the analyses. Therefore non-parametric analysis was not performed. Sexes were analyzed separately in the experiment 1. In subsequent studies, the sexes were not separated due to the smaller group sizes.

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

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): negative
The sample of unrefined lubricating oil was not considered mutagenic.
Executive summary:
 In an in-vivo test, neat ULO was administered to CD-1 mice (2/sex/dose) on two consecutive daily doses via oral gavage at dose levels of 0, 1.25, 2.5, or 5.0 g/kg. Bone marrow cells were harvested at 24 hours following the final dose and evaluated for micronucleus formation. 

 

There were no signs of clastogenicity the study. The positive and negative controls induced the appropriate response.