Registration Dossier

Administrative data

Endpoint:
sub-chronic toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Cross-reference
Reason / purpose:
read-across: supporting information

Data source

Reference
Reference Type:
review article or handbook
Title:
2-METHYLPENTANE (ISOHEXANE)
Author:
Galvin, Jennifer B.; Bond, Gary
Year:
1999
Bibliographic source:
Journal of Toxicology and Environmental Health, Part A, 58:1-2, pp. 81-92, DOI: 10.1080/009841099157449; http://dx.doi.org/10.1080/009841099157449

Materials and methods

GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Specific details on test material used for the study:
98% pure 2-methylpentane

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male

Administration / exposure

Route of administration:
inhalation
Duration of treatment / exposure:
14 weeks
Frequency of treatment:
9 h/d, 5 d/wk
Doses / concentrations
Dose / conc.:
1 500 ppm

Results and discussion

Results of examinations

Clinical signs:
not specified
Mortality:
not specified
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
significant decrease in body weight gain
Food consumption and compound intake (if feeding study):
not specified
Food efficiency:
not specified
Water consumption and compound intake (if drinking water study):
not specified
Ophthalmological findings:
not specified
Haematological findings:
not specified
Clinical biochemistry findings:
not specified
Urinalysis findings:
effects observed, treatment-related
Description (incidence and severity):
24-h urine sample, 1 metabolite, 2-methyl-2-pentanol
Behaviour (functional findings):
not specified
Immunological findings:
not specified
Organ weight findings including organ / body weight ratios:
not specified
Gross pathological findings:
effects observed, non-treatment-related
Description (incidence and severity):
No significant differences in hindlimb spreads but high individual variability
Neuropathological findings:
no effects observed
Description (incidence and severity):
No signs of neuropathy
Histopathological findings: non-neoplastic:
no effects observed
Description (incidence and severity):
histology (glutaraldehyde perfusion): no pathological alterations of tissue
Histopathological findings: neoplastic:
not specified

Effect levels

Dose descriptor:
LOEL
Effect level:
< 1 500 ppm
Based on:
test mat.
Sex:
male
Basis for effect level:
body weight and weight gain

Applicant's summary and conclusion

Conclusions:
There were no signs of neuropathy in any of the animals in the Frontali et al. study on 2-methylpentane. After the exposure period ended, samples of nerves were processed for light microscopy. Sections of teased nerve fibers showed no pathological alterations of tissue from the 2-methylpentane-exposed animals. There was a significant decrease in body weight gain for 2-methylpentane. There were no significant differences in hindlimb spread but there was high individual variability. Rats treated with n-hexane developed the typical giant axonal degeneration. The 24-h urine sample from rats exposed to 1500 ppm 2-methylpentane showed only 1 metabolite, 2-methyl-2-pentanol.
Executive summary:

Frontali et al. (1981) designed a study to investigate whether the isomers of hexane caused axonal degeneration. Therefore, he studied inhalation exposures to n-heptane, 2-methylpentane, 3-methylpentane, n-pentane, cyclohexane, and n-heptane. He varied the exposure regimen for the different chemicals. In the case of 2-methylpentane (98% pure), rats were exposed to 1500 ppm for 9 h/d, 5 d/wk, for 14 wk.