The Toxicity of Inhaled Methanol Vapors

Abstract

Methanol could become a major automotive fuel in the U.S., and its use may result in increased exposure of the public to methanol vapor. Nearly all of the available information on methanol toxicity in humans relates to the consequences of acute, rather than chronic, exposu res. Acute methanol toxicity evolves in a well-understood pattern and consists of an uncompensated metabolic acidosis with superimposed toxicity to the visual system. The toxic properties of methanol are rooted in the factors that govern both the conversion of methanol to formic acid and the subsequent metabolism of formate to carbon dioxide in the folate pathway. In short, the toxic syndrome sets in if formate generation continues at a rate that exceeds its rate of metabolism. Current evidence indicates that formate accumulation will not challenge the metabolic capacity of the folate pathway at the anticipated levels of exposu re to automotive methanol vapor.

A Pharmacokinetic Model of Inhaled Methanol in Humans and Comparison to Methanol Disposition in Mice and Rats

“…A worker exposed for 8 (20). Indeed, this inhibition has been used for treatment of acute methanol toxicity, since ethanol slows the conversion of methanol to formate (1). Furthermore, this inhibition is significant at relatively low doses of ethanol.…”

“…Blood toxicant levels are a more relevant determinant of systemic effects (such as teratogenicity) than are ambient environmental toxicant concentrations (12 (1), the primate is the model of choice for both kinetic and toxicologic studies of methanol, and only data obtained from human and nonhuman primates in the published literature were used in this study. Numerical values presented in tables were preferred to values that were scaled from charts or graphs, although the majority of data were scaled.…”

Medical toxicology and public health—Update on research and activities at the centers for disease control and prevention, and the agency for toxic substances and disease registry

“…It is commonly used in varnishes, windshield wiper fluid, adhesives, and antifreeze [7]. Low-level exposure to methanol occurs from ingestion of fresh fruit and vegetables, the artificial sweetener aspartame when it is metabolized [9], and through endogenous demethylation metabolic pathways.…”

“…There are also reports of children who have died from dermal exposure to methanol [13]. Chronic and acute exposures to methanol vapors have been studied at or near the limits of allowable methanol vapor exposure [9,[14][15] …”

“…The optic nerve fibers may be more susceptible, secondary to lower levels of cytochrome oxidase [9,37]. In serious cases, injury may occur in the basal ganglia, with the putamen appearing to be very susceptible [38][39][40].…”