Registration Dossier

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
Study period:
1979
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: This study was conducted prior to GLP and test guidelines, but sufficient data is available for interpretation of results

Data source

Reference
Reference Type:
publication
Title:
Mutagenic evaluation of nitroparaffins in the Salmonella typhimurium/ mammalian-microsome test and the micronucleus test
Author:
Hite M and Skeggs H.
Year:
1979
Bibliographic source:
Environ Mutagen 1:383-389

Materials and methods

Principles of method if other than guideline:
Mice were orally administered doses of nitroethane as high as half of the LD50 value. In this test the incidence of micronuclei in polychromatic erythrocytes was examined. Used the method of Schmid W: Chemical mutagen testing on in vivo somatic mammalian cells. Agents Actions 3:77-85, 1973.
GLP compliance:
not specified
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
No additional information available.

Test animals

Species:
mouse
Strain:
CD-1
Sex:
male/female
Details on test animals and environmental conditions:
The mice used to study nitroethane were of the Charles River (CD-1) strain. At the initiation of the study, the animals were about five weeks old. The males weighed 26.0-31.0 g and the females weighed 20.0-24.6 g. Mice were maintained in standard mouse boxes in an air-conditioned room (about 22C) with free access to food (Wayne Lab Blox) and water at all times.

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
No information.
Details on exposure:
Nitroethane was given orally in dosages of 0.25, 0.50 and 1.00 ml/kg/day. Dosages were selected on the basis of the highest tolerated doses in acute oral toxicity studies. In our laboratory, the 14-day oral LD50 in CD-1 mice was calculated to be 2.15 (1.74 - 2.66) ml/kg for nitroethane.
Duration of treatment / exposure:
See above.
Frequency of treatment:
Mice were given two daily doses of the appropriate compound.
Post exposure period:
Six hours after the last dose the animals were sacrificed by cervical dislocation.
Doses / concentrations
Remarks:
Doses / Concentrations:0.25, 0.50 and 1.00 ml/kg/dayBasis:other: oral gavage
No. of animals per sex per dose:
14 male and 14 female controls8 males and 8 females/dose group
Control animals:
other: 1.0 ml/kg/day tap water orally
Positive control(s):
methylmethanesulfonate, 90 mg/kg/day, ip

Examinations

Tissues and cell types examined:
Bone marrow from both femora was harvested and prepared for microscopic analysis after the method of Schmid (1973). ReferenceSchmid, W. (1973). Chemical mutagen testing on in vivo somatic mammalian cells. Agents Actions 3:77-85
Details of tissue and slide preparation:
The marrow from each mouse was evacuated from the marrow canal into a siliconized centrifuge tube, using fetal calf serum, and the tubes were centrifuges for five minutes at 1000 rpm. The supernatant was removed with Pasteur pipettes, and the cells were then resuspended by mixing gently with siliconized pipettes in the small amount of serum remaining in the capillary part of the test tube. A drop of the cell suspension was placed on a clean glass microscope slide and spread in the conventional manner. Four slides were prepared for each mouse. The smears were air-dried on a slide dryer at 37C and dipped briefly into absolute methanol for fixation. The slides were stained with May-Grunwald Geimsa stain. The microscope slides were coded so that they could be read in a blind and random fashion. Approximately 3000 erythrocytes (polychromatic and normochromatic) from each mouse were examined for the presence of micronuclei.
Evaluation criteria:
No additional information available.
Statistics:
The results were statistically analyzed by an analysis of variance procedure using a rankit transformation of the data and Fisher's Least Significance Difference procedure for joint comparison between the negative control and a treated group (Harter (1960); Snedecor et al., (1967)).References:Harter, H.L. (1960). Expected values of normal order statistics. Biometrika 48:151-165Snedecor, G.W. and Cochran, W.G. (1967). Statistical Methods, 6th Ed. Ames, Iowa, Iowa State University Press, p 272.

Results and discussion

Test results
Sex:
male/female
Genotoxicity:
negative
Toxicity:
no effects
Vehicle controls validity:
not examined
Negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
Nitroethane did not cause a significant increase in the numbers of polychromatic erythrocytes with micronuclei when compared to corresponding negative control groups of mice. No evidence of a sex-related difference in the response to treatment was seen.The positive control agent, methyl methanesulfonate, gave the anticipated positive results in both studies.

Any other information on results incl. tables

Table 1 Micronucleus test in the mouse percent polychromatic erythrocytes with micronuclei.

 Sex (number)  Nitroethane
 0 (tap water), 1.0 ml/kg/day, p.o.  
 Female (14)  0.64
 Male (14)  0.53
 Combined (28)  0.58
 0.25 ml/kg/day, p.o.  
 Female (8)  0.44
 Male (8)  0.51
 Combined (16)  0.48
 0.50 ml/kg/day, p.o.  
 Female (8)  0.47
 Male (8)  0.67
 Combined (16)  0.57
 1.0 ml/kg/day, p.o.  
 Female (8)  0.57
 Male (8)  0.60
 Combined (16)  0.59
 Positive Control - methyl methanesulfonate, 90 mg/kg/day, i.p.  
 Female (5)  6.09*
 Male (5)  5.76*
 Combined (10)  5.92*

*Significant at P<0.001

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): negativeNitroethane did not cause a significant increase in the numbers of polychromatic erythrocytes with micronuclei when compared to corresponding negative control groups of mice. No evidence of a sex-related difference in the response to treatment was seen.
Executive summary:

The mutagenic potential of nitroethane was evaluated in the mouse micronucleus test. Nitroethane did not cause a significant increase in the numbers of polychromatic erythrocytes with micronuclei when compared to corresponding negative control groups of mice. No evidence of a sex-related difference in the response to treatment was seen.