The National Institute on Alcohol Abuse and Alcoholism maintains a database of alcohol-related health effects. [81]
| BAC (mg/dL) | Symptoms[82] |
|---|---|
| 50 | Euphoria, talkativeness, relaxation |
| 100 | Central nervous system depression, impaired motor and sensory function, impaired cognition |
| >140 | Decreased blood flow to brain |
| 300 | Stupefaction, possible unconsciousness |
| 400 | Possible death |
| >550 | Death |
Ethanol is a central nervous system depressant and has significant psychoactive effects in sublethal doses; for specifics, see effects of alcohol on the body by dose. Based on its abilities to change the human consciousness, ethanol is considered a drug.[83] Death from ethyl alcohol consumption is possible when blood alcohol level reaches 0.4%. A blood level of 0.5% or more is commonly fatal. Levels of even less than 0.1% can cause intoxication, with unconsciousness often occurring at 0.3–0.4%.[84]
The amount of ethanol in the body is typically quantified by blood alcohol content (BAC), the milligrams of ethanol per 100 milliliters of blood. The table at right summarizes the symptoms of ethanol consumption. Small doses of ethanol generally produce euphoria and relaxation; people experiencing these symptoms tend to become talkative and less inhibited, and may exhibit poor judgment. At higher dosages (BAC > 100 mg/dl), ethanol acts as a central nervous system depressant, producing at progressively higher dosages, impaired sensory and motor function, slowed cognition, stupefaction, unconsciousness, and possible death.
In America, about half of the deaths in car accidents occur in alcohol-related crashes.[85] There is no completely-safe level of alcohol for driving; the risk of a fatal car accident rises with the level of alcohol in the driver"s blood.[86] However, most drunk driving laws governing the acceptable levels in the blood while driving or operating heavy machinery set typical upper limits of blood alcohol content (BAC) between 0.05% to 0.08%.
Ethanol within the human body is converted into acetaldehyde by alcohol dehydrogenase and then into acetic acid by acetaldehyde dehydrogenase. The product of the first step of this breakdown, acetaldehyde,[87] is more toxic than ethanol. Acetaldehyde is linked to most of the clinical effects of alcohol. It has been shown to increase the risk of developing cirrhosis of the liver,[77] multiple forms of cancer, and alcoholism.
Ethanol can intesify the sedation caused by other central nervous system depressant drugs such as barbiturates, benzodiazepines, opioids, and phenothiazines[84]
Some individuals have less-effective forms of one or both of the metabolizing enzymes, and can experience more-severe symptoms from ethanol consumption than others. Conversely, those who have acquired alcohol tolerance have a greater quantity of these enzymes, and metabolize ethanol more rapidly.[88]
Ethanol is classified as a teratogen. See fetal alcohol syndrome.
Frequent drinking of alcoholic beverages has been shown to be a major contributing factor in cases of elevated blood levels of triglycerides.[89]
Ethanol is not a carcinogen.[90][91] However, the first metabolic product of ethanol, acetaldehyde, is toxic, mutagenic, and carcinogenic. Also, ethanol"s effect on the liver can contribute to immune suppression. Consequently, consumption of alcoholic beverages can be an aggravating factor in carcinogenesis.
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