Methanol is a widely used industrial solvent also found in some household chemicals.
Symptoms of Methanol Poisoning:
Upset stomach, dizziness, vision problems.
Symptoms reappear six to 30 hours later with greater severity.
Methanol is a clear, colourless liquid with a faint odor like alcohol. The smell is not very strong and is considered a poor indicator of vapor concentration. You might also know methanol as methyl alcohol, methyl hydrate, carbinol, wood alcohol or wood spirit.
Methanol is used as a solvent for lacquers, paints, varnishes, cements, inks, dyes, plastics and various industrial coatings. It is also used in the production of pharmaceuticals, formaldehyde and other chemical products. Methanol appears as an ingredient in many products, from industrial solvents to windshield-washer fluid and nail-polish remover. It is also used as a fuel.
Inhalation of methanol vapor is the most common route of occupational exposure. Poisonings have also resulted from absorption through the skin; although it is only a mild skin irritant, it can be absorbed through the skin in toxic amounts. Accidental swallowing is also possible.
Methanol tastes and smells much like common alcohol (ethanol) and has been used as a substitute in illegal alcoholic beverages. In March 1997, three people died in northern Ontario as a result of methanol poisoning from a bad batch of moonshine.
Effects of Methanol Poisoning
As little as four milliliters can cause blindness and 80 to 150 milliliters can be fatal; about half a milliliter per kilogram of weight is deadly.
Drinking methanol causes effects similar to common alcohol, such as an upset stomach and dizziness, with the addition of pronounced vision problems. After these effects disappear, they reappear six to 30 hours later, only with much greater severity. Severe symptoms tend to appear 18 to 24 hours after consumption. The relapse time makes it imperative to seek medical help as soon as possible.
The most seriously poisoned lose consciousness and die of respiratory or heart failure. Those who do not die may stay in a coma for as long as a week and may be left blinded.
Accidental swallowing of methanol is not likely in the workplace. Should it happen, get medical help immediately. Never try to make the casualty throw up, but if that does happen hold the person leaning forward to reduce the risk of methanol being drawn into the lungs. You can give 240 to 300 milliliters of water to dilute the methanol in the stomach.
Like common alcohol, methanol is broken down in the liver. Methanol breaks downs to produce formaldehyde and formic acid, which are responsible for many of the toxic effects. The body takes several days to eliminate the methanol.
Short-term exposure to methanol vapor can irritate the eyes, nose and throat and cause headache, nausea, throwing up, dizziness and trouble breathing. Other common symptoms of drunkenness, such as lightheadedness, giddiness, blurred vision and dilated pupils, might also appear. The symptoms depend on the level and length of exposure and can vary from person to person.
Industrial exposures to methanol vapors can cause death or blindness. Many reported incidents have involved working in confined spaces without proper ventilation or respiratory protection. Fortunately, increased awareness of the dangers of methanol, combined with safer work practices, have reduced the number of serious poisonings in recent years.
Long-term exposure to methanol has been linked to headaches, mood changes, eye and skin irritation, trouble sleeping, stomach problems and visual impairment. Repeated short-term exposures can also lead to such symptoms.
Methanol is a flammable liquid and can pose a serious fire risk. It burns with a pale blue flame not usually visible in normal light. Its flash point is 12 c. above this temperature enough vapor is produced to create a flammable mixture with air. The vapor is heavier than air and can travel along the ground to a distant source of ignition and flashback. Containers may explode in the heat of a fire. Although methanol is normally stable, contact with strong oxidizing agents increases the risk of a fire or explosion.
How To Protect Yourself
Wear proper protective clothing to shield yourself against methanol liquid or concentrated vapor. Never make substitutions for the protective clothing designated for use when working with methanol — it can dissolve some materials. Remove contaminated clothing immediately and thoroughly rinse down exposed skin areas.
In some situations, special clothing and respirators are essential. Such situations include working in confined spaces, some maintenance operations, and other work environments where effective ventilation and engineering controls are not possible.
Always wear splash-proof chemical goggles or a face shield whenever there’s a risk of splashing liquid into your eyes.
The above is intended as useful general information to supplement existing occupational health and safety programs. It is not suitable as a replacement for a proper full program.
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