Subchronic (12-week) inhalation toxicity study of methanol-fueled engine exhaust in rats

Journal Article · Sat Jan 01 00:00:00 EST 1994 · Journal of Toxicology and Environmental Health; (United States)

DOI:https://doi.org/10.1080/15287399409531846· OSTI ID:7181269

Maejima, Kazuhito; Suzuki, Tadao ^[1]; Numata, Hiroaki ^[2]; Maekawa, Akihiko ^[3]; Nagase, Sumi ^[4]; Ishinishi, Noburu ^[5]

---

1. Japan Automobile Research Institute Inc., Ibaraki (Japan)
2. Bozo Research Center, Shizuoka (Japan)
3. Sasaki Institute, Tokyo (Japan)
4. Nagase Institute, Ibaraki (Japan)
5. Nakamura-Gakuen College, Fukuoka (Japan)

To evaluate the inhalation toxicity to rats of exhaust at low concentration for longer periods, Fischer 344 rats were exposed to 3 concentrations of exhaust generated by an M85 methanol-fueled engine (methanol with 15% gasoline) without catalyst for 8 h/d, 6 d/wk for 4, 8, or 12 wk. Concentration- and time-dependent increase carboxyhemoglobin in the erythrocytes and decrease in cytochrome P-450 in the lungs were observed in all treated groups. Furthermore, significant increases in plasma formaldehyde were observed in the group exposed to the highest concentration of exhaust (carbon monoxide, 89.8 ppm; formaldehyde, 2.3 ppm; methanol, 8.1 ppm; nitrogen oxides, 22.9 ppm; nitrogen dioxide, 1.1 ppm) for 8 or 12 wk. No change of plasma folic acid was observed in any group, and no methanol or formic acid was detected in the plasma in any animals. Histopathologically, exposure-related changes were found only in the nasal cavity of the high-concentration group. Slight hyperplasia/squamous metaplasias of the respiratory epithelium lining the nasoturbinate and maxilloturbinate were observed after 4 wk of exposure, and the incidences and degrees of these lesions increased slightly with the exposure time. No changes were found in the olfactory epithelium of the nasal cavity. As judged by optical microscopy, the exhaust concentration with no effect on the nasal cavity under the experimental conditions was concluded to be the medium concentration level containing 0.55 ppm formaldehyde. In the present study, however, concentration- and time-dependent increase of carboxyhemoglobin in the erythrocytes and decrease of the lung P-450 level were observed. Therefore, further study on more long-term inhalation of lower concentrations of exhaust might be needed. 31 refs., 2 figs., 3 tabs.

• OSTI ID: 7181269
• Journal Information: Journal of Toxicology and Environmental Health; (United States), Vol. 41:3; ISSN 0098-4108
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
59 BASIC BIOLOGICAL SCIENCES
CARBOXYHEMOGLOBIN
BIOLOGICAL ACCUMULATION
EXHAUST GASES
CHRONIC EXPOSURE
DOSE-RESPONSE RELATIONSHIPS
METHANOL
TOXICITY
RATS
RESPONSE FUNCTIONS
FORMIC ACID
ALCOHOLS
ANIMALS
CARBOXYLIC ACIDS
FLUIDS
FUNCTIONS
GASEOUS WASTES
GASES
HYDROXY COMPOUNDS
MAMMALS
MONOCARBOXYLIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
RODENTS
VERTEBRATES
WASTES
560300* - Chemicals Metabolism & Toxicology
550500 - Metabolism