Alcohol intoxication destroys the liver and affects the brain, causing slurred speech, clumsiness, and delayed reflexes. Severe alcohol poisoning can be fatal. A blood alcohol content of .45% in test animals results in a median lethal dose. This means that .45% is the concentration of blood alcohol that is fatal in 50% of the test subjects. That is about six times the level of ordinary intoxication (0.08%), but vomiting or unconsciousness may occur much sooner in people who have a low tolerance for alcohol. The high tolerance of chronic heavy drinkers may allow some of them to remain conscious at levels above .40%, although serious health dangers are incurred at this level. Alcohol also limits the production of vasopressin (ADH) from the hypothalmus and the secretion of this hormone from the posterior pituitary gland. This is what causes severe dehydration when large amounts of alcohol are drunk. It also causes a high concentration of water in the urine and vomit and the intense thirst that goes along with a hangover. All in all drinking alcohol is a highly damaging practice and not recommended.