Ethanol

Repeated dose toxicity: inhalation

Administrative data

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Not a guideline study and publication does not report whether study performed according to GLP. Only a single dose used (ie effectively a limit dose study) However, data appears well documented and scientifically acceptable.

Data source

Reference

Reference Type:

publication

Title:

Effects of an ethanol-gasoline mixture: results of a 4-week inhalation study in rats

Author:

Chu I, Poon R, Valli V, Yagminas A, Bowers WJ, Seegal R, Vincent R

Year:

2005

Bibliographic source:

J Appl Toxicol. 25: 193-199

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

As part of a study to investigate the inhalation toxicity of an ethanol-gasoline mixture, the toxicological and neurochemical effects of ethanol alone were investigated in male and female rats following a 4-week inhalation exposure, and incorporating a 4 week recovery phase.

GLP compliance:

not specified

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Ethanol

EC Number:

200-578-6

EC Name:

Ethanol

Cas Number:

64-17-5

Molecular formula:

C2H6O

IUPAC Name:

ethanol

Details on test material:

- Name of test material (as cited in study report): ethanol
- Analytical purity: >99%

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Administration / exposure

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

4 weeks (total of 20 days exposure).

Frequency of treatment:

Rats placed in the inhalation chambers for 6 h/day (7.30am-13.30pm), 5 days/week

Doses / concentrations

Remarks:

Doses / Concentrations:
0 or 6130 ppm ethanol
Basis:
no data

No. of animals per sex per dose:

Ten male and 10 female rats per dose (0 or 6130 ppm ethanol) for main study, and additional groups of 5 male and 5 female rats following treatment were exposed to filtered air for a further 4 weeks (recovery phase) to determine reversibility of effects.

Control animals:

yes

Results and discussion

Effect levels

Dose descriptor:

NOAEC

Effect level:

>= 6 130 ppm

Sex:

male/female

Basis for effect level:

other: No adverse effects were observed in male and female rats exposed to 6130 ppm ethanol, other than a number of mild effects regarded as adaptive, and that had generally returned to normal following a 4 week recovery period.

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

The investigators reported that only mild, adaptive, effects were seen in ethanol-exposed animals, which had in general returned to normal after cessation of exposure. There was a slight (but statistically significant) increase in relative thymic weight seen in male rats exposed to ethanol (compared to controls), although this had returned to normal after the 4 week recovery phase. Ethanol-exposed female rats at the end of the recovery period showed a slight (but statistically significant) increased relative heart weight, but this was not evident immediately following the 4 -weeks of ethanol exposure. Similarly, treated female rats in the recovery group had a statistically significantly increased serum glucose level, but again this was not apparent immediately following ethanol exposure.

Slight (but statistically significant) neurochemical changes in the brain were reported in female rats exposed to ethanol (compared to controls) [although it is not clear if these were seen immediately following the exposure to ethanol, or were still evident at the end of the 4 -week recovery phase].

There were no treatment-related clinical signs of toxicity and no gross pathological or histological changes were reported on examination of the major organs. Body weights, liver enzyme levels, haematology, and clinical chemistry parameters were otherwise normal.

Applicant's summary and conclusion

Conclusions:

Inhalation of ethanol at 6130 ppm 6h/day, 5 days/week, for 4 weeks produced only mild effects that were regarded by the investigators as adaptive, and had generally returned to normal following a 4 week recovery phase. Exposure to ethanol resulted in some slight brain neurochemical alterations that were gender-specific, with female rats appearing to be more sensitive than males. The toxicological significance of these changes is not clear.

Executive summary:

As part of a study to investigate the inhalation toxicity of an ethanol-gasoline mixture, groups of 15 male and 15 female rats were exposed in an inhalation chamber to 0 or 6130 ppm ethanol, 6 hours/day, 5 days/week, for 4 weeks. Five animals of each sex/group were then exposed to filtered air for a further 4 -weeks recovery period prior to assessment.

Following exposure to ethanol, the investigators reported only mild, adaptive, effects that had generally returned to normal by the end of the recovery period. No clinical signs of toxicity were observed, and there were no gross or microscopic tissue changes seen on examination of a range of major organs (including the heart, liver, spleen, kidney, brain, testes, and thymus).