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Taken internally in low doses, ethanol acts as a mild CNS stimulant and euphoriant, perhaps by enhancing acetylcholine neuroreceptor activity. Larger doses cause a reversible neurotoxicity manifested by altered sensorium, mydriasis, diplopia, nystagmus, dysequilibrium, tremor, slurred speech, incoordination, and general CNS depression proceeding from disorientation and deterioration of judgment to stupor, coma, and death due to respiratory arrest. Suppression of the gag reflex can lead to aspiration of vomitus. Nonneurologic effects of ethanol include tachycardia, vasodilatation, diaphoresis, diuresis, nausea, vomiting, and acute gastritis. Toxic effects of ethanol can be modified or aggravated by other substances (medicines, drugs of abuse) consumed along with it. About 25% of swallowed alcohol is absorbed through the gastric mucosa, and most of the rest from the duodenum. The rate at which ethanol is absorbed from the digestive tract depends on the concentration consumed, the type and quantity of food also present, and collateral factors such as disease or medicine that affect gastrointestinal function and motility. At least 90% of absorbed ethanol is converted in the liver to acetaldehyde, which is in turn converted to acetate. Acetaldehyde is also toxic, and is responsible for some of the symptoms of acute alcoholic intoxication and of a hangover. Small amounts of ethanol are excreted unaltered by the lungs and kidneys. For medical and forensic purposes, the level of ethanol in the blood is measured as the weight of ethanol per volume of blood and expressed as a percentage. Thus, an ethanol concentration of 100 mg/dL (21.7 mmol/L) corresponds to 0.1% (a level widely used in legal definitions of alcoholic intoxication). One ounce (30 mL) of 100-proof whiskey, 4 ounces (120 mL) of wine, or 12 ounces (360 mL) of beer yield a blood alcohol concentration of about 0.02% in a 150-pound human subject. Because this is roughly the amount of ethanol that can be cleared from the blood in 1 hour, consumption of alcoholic beverages at a rate exceeding one such drink per hour leads to a gradual increase of blood alcohol concentration. Women achieve higher blood levels than men with equivalent doses of ethanol. Measurable cognitive impairment occurs at a blood alcohol level of about 0.05%, gait disturbances at 0.10%, slurred speech at 0.15%. A level of 0.3-0.4% leads to unconsciousness, and respiratory arrest occurs around 0.5%. Regular consumption of alcohol in moderation (one drink/day for women, two/day for men) confers a modest reduction in the risk of coronary artery disease and in all-cause mortality, a benefit that is lost with even slightly higher levels of alcohol consumption. Ethanol is the most frequently abused drug in the United States. U.S. residents spend $116 billion each year on alcoholic beverages and the annual cost of alcohol abuse to the national economy is $200 billion. Thirty percent of U.S. adults drink to excess at least occasionally, and 30% of U.S. high school students admit to binge drinking at least once a month. Among young people, there exists a strong association between alcohol abuse and the use of tobacco and illicit drugs. Integral to much drinking behavior is the decline in resistance to further drinking with a rise in blood alcohol level. The chronic abuse of alcohol is associated with an increased incidence of hypertension, stroke, cirrhosis, gastritis, pancreatitis, malnutrition, vitamin deficiency, Wernicke encephalopathy, and Korsakoff psychosis. A child born to an alcoholic mother may bear the stigmata of fetal alcohol syndrome. Regular heavy alcohol consumption is an established cause of cancers of the oral cavity, pharynx, larynx, esophagus, liver, and breast.
Synonym(s): ethanol, ethyl alcohol.