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Administrative data

Endpoint:
short-term repeated dose toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions

Data source

Reference
Reference Type:
publication
Title:
Subchronic inhalation toxicity of methanol
Author:
Andrews L S
Year:
1987
Bibliographic source:
Journal of Toxicology and Environmental Health, 20:1-2, 117-124

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 412 (Subacute Inhalation Toxicity: 28-Day Study)
Deviations:
yes
Remarks:
Very limited extent of examinations (see: observations and examinations performed)
GLP compliance:
not specified
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
Methanol
EC Number:
200-659-6
EC Name:
Methanol
Cas Number:
67-56-1
Molecular formula:
CH4O
IUPAC Name:
Methyl alcohol
Test material form:
liquid

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 Laboratories, Kingston, N.Y.
- Age at study initiation: 50 days
- Weight at study initiation: mean males 247-256 g; meanfemales 158-163 g
- Fasting period before study: no
- Housing: no data
- Diet (e.g. ad libitum): Purina Laboratory Chow 5001 ad libitum
- Water (e.g. ad libitum): tap water ad libitum
- Acclimation period: 15 days

Administration / exposure

Route of administration:
inhalation: vapour
Type of inhalation exposure:
whole body
Vehicle:
not specified
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: 4 m³ exposure chambers constructed of glass and stainless steel
- Method of holding animals in test chamber: individual in rack-mounted wire-mesh cages, positions of individual animals rotated on the rack during the study
- Source and rate of air: house supply
- Method of conditioning air: no data
- System of generating particulates/aerosols: Ambient flash evaporation by a Spraying Systems Atomizer (quarter-inch J nozzle with 1A spray set-up), mounted in the inlet port of the exposure chamber; the aerosol droplets evaporated in the inlet air stream to yield a vapor in the exposure chamber
- Temperature, humidity, pressure in air chamber: no data
- Air flow rate: 2000 L/min
- Air change rate: 20/h
- Method of particle size determination: not applicable
- Treatment of exhaust air: no data

TEST ATMOSPHERE
- Brief description of analytical method used: Wilkes MIRAN 1A-CVF infrared analyzer
- Samples taken from breathing zone: no data
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Based on infrared analysis of chamber atmospheres, animals received eposure to mean concentrations of 520, 1980 and 5010 ppm, respectively. Mean nominal concentrations were 550, 2330 and 5330 ppm. Occasional discrepancies between nominal and analytical values were within the limits of expected experimental error (± 10 %).
Duration of treatment / exposure:
4 weeks
Frequency of treatment:
6 h/d, 5 d/wk
Doses / concentrationsopen allclose all
Dose / conc.:
0 ppm
Dose / conc.:
520 ppm (analytical)
Remarks:
(0.69 mg/L)
Dose / conc.:
1 980 ppm (analytical)
Remarks:
(2.63 mg/L)
Dose / conc.:
5 010 ppm (analytical)
Remarks:
(6.67 mg/L)
No. of animals per sex per dose:
5
Control animals:
yes, sham-exposed
Positive control:
none

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice each day
- Cage side observations included: mortality, clinical signs of toxicity

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: once each week

BODY WEIGHT: Yes
- Time schedule for examinations: prior to study initiation, first day of exposure and weekly thereafter.

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: No

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: pretest and at termination
- Dose groups that were examined: all animals: lids, lacrimal apparatus, and conjunctiva were examined grossly, the cornea, anterior chamber, lens, vitreous humor, retina, and optic disc were examined by indirect ophthalmoscopy. Mydriasis was induced by atropine.

HAEMATOLOGY: No

CLINICAL CHEMISTRY: No

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No
Sacrifice and pathology:
GROSS PATHOLOGY: Yes. The external body surfaces, all orifices, body cavities and their visceral organs, cervical tissues and organs, and carcass were examined. Tissues and organs were examined in situ and after removal. Organ weights were taken for the adrenal glands (paired), heart, kidneys (paired), liver, lungs, spleen, testes (with epididymides paired), and ovaries (paired).
HISTOPATHOLOGY: Yes. Approximately 35 different tissues per animal were preserved for microscopic examination: eyes, testes, epididymides, lungs, bone marrow smears. Slides from the nasal turbinates, trachea, lungs, kidneys, esophagus, liver, and eye (with optic nerve) from all animals from control and high-exposure groups were prepared and examined microscopically. Only one eye (randomly selected) per animal was examined microscopically.
Statistics:
Body weights, organ weights, and organ/body weight ratios were compared by a statistical evaluation of equality of means. This was done using the appropriate one-way analysis of variance technique, followed by a multiple-comparison procedure if needed. First, Bartlett's test was performed to determine if groups had equal variance. If the variances were equal, parametric procedures were used; if not, nonparametric procedures were used. The parametric procedures were the standard one-way ANOVA used to determine which means were significantly different from the control. If a nonparametric procedure for testing equality of means was needed, the Kruskal-Wallis test was used, and if differences were indicated, a summed-rank test was used to determine which treatments differed from the control. A statistical test for trend in the dose levels was also performed. In the parametric case (i.e., equal variance), standard regression techniques with a test for trend and lack of fit were used. In the nonparametric case, Jonckheere's test for monotonic trend was used. The test for equal variance (Bartlett's) was conduced at the 1%, two-sided risk level. All other statistical tests were conducted at the 5% and 1% two-sided risk levels. Statistical evaluations were not performed when the standard error for the control group or more than one group was 0.0 due to lack of variance. If a standard error for one treated group was 0.0 or when N (number of animals) was less than or equal to 2 animals for any treated group, it was not included in the statistical evaluation.

Results and discussion

Results of examinations

Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
Increased frequencies of nasal and eye discharge (lacrimation, mucoid nasal discharge, red nasal discharge, and dried red nasal discharge) were noted in the treated groups. Only mucoid nasal discharge appeared to be dose-related.
Mortality:
no mortality observed
Description (incidence):
All animals survived.
Body weight and weight changes:
effects observed, non-treatment-related
Description (incidence and severity):
There were no treatment-related effects on body weight.
Food consumption and compound intake (if feeding study):
not examined
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
no effects observed
Description (incidence and severity):
No ocular abnormalities were noted at the terminal examination of the high-dose group.
Haematological findings:
not examined
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
no effects observed
Organ weight findings including organ / body weight ratios:
effects observed, non-treatment-related
Description (incidence and severity):
Relative spleen weights were significantly (p ≤ 0.05) increased in female rats exposed at 1980 ppm (not at 5010 ppm). However, these differences by themselves are not of any apparent biological significance. No other organ weight effects were noted.
Gross pathological findings:
no effects observed
Description (incidence and severity):
No treatment-related effects were noted.
Neuropathological findings:
no effects observed
Histopathological findings: non-neoplastic:
effects observed, non-treatment-related
Description (incidence and severity):
No treatment-related histopathological effects were noted.
Histopathological findings: neoplastic:
not examined
Other effects:
no effects observed

Effect levels

Key result
Dose descriptor:
NOAEC
Effect level:
5 010 ppm (analytical)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: no significant effects at the highest concentration tested

Target system / organ toxicity

Key result
Critical effects observed:
no

Applicant's summary and conclusion

Conclusions:
In a repeated dose toxicity study with methanol, rats exposed to up to 5010 ppm (6 hr/d, 5d/wk for 4 weeks) showed no treatment-related histopathological effects. Inhalation exposure only resulted in some slight treatment-related signs.
Executive summary:

A short-term repeated dose toxicity study (inhalation route) was performed on methanol according to a similar method to OECD guideline 412. Groups of 5 male and 5 female rats were exposed to the test item by whole body inhalation at concentrations of 0, 520, 1980 and 5010 ppm, 6 hours per day, 5 days per week for 4 weeks. During the study, clinical observations, bodyweight, organ weight, ophthalmoscopic examination, macropathology and histopathology were undertaken. The only treatment and dose-related effect noted was that of mucoid nasal discharge in rats, which was considered reflective of upper respiratory tract irritation. No consistent treatment-related effects were found for organ or body weights or for histopathologic or ophthalmoscopic examinations. These results suggest that a NOAEL of 5010 ppm equivalent to 6.67 mg/L can be established for the test substance.