Alcohol is one of the most problematic drugs that cause traffic accidents. And yes, alcohol is most definitely a drug. Though there is decent education going on targeted against drunk driving, and though the number of deaths by drunk driving has been slowly decreasing, it still remains a tremendous problem. This site is targeted primarily at driving under the influence of alcohol.
What exactly is alcohol? Speaking chemically, alcohols are a class of organic compounds. So under the class of alcohol, there are actually many different molecules. The one that we commonly call alcohol -- the kind found in alcoholic beverages -- is called ethanol or ethyl alcohol. The chemical formula for ethanol is C2H6O. Ethanol is the compound in alcoholic beverages which is absorbed into the bloodstream and affects the workings of the nervous system. Ethanol is a clear, colorless liquid, and is produced by the fermentation of fruits and vegetables. The color of alcoholic beverages comes from other additives and byproducts of the fermentation process.
Different kinds of drinks contain different concentrations of alcohol. These concentrations are usually measured as a "proof" rating. Proof is a lot like percentage, except that a 200 proof drink is 100% alcohol. The proof rating is twice the percentage of alcohol. This fact often breeds the idea that it is safer to drink wine than hard liquor, since hard liquor has a higher alcohol concentration. However, though the hard liquor has a higher concentration, you will notice that it is consumed in lower quantities. Shot glasses only hold about 1½ ounces of beverage, while wine glasses hold on average about 5 ounces of wine. Interestingly enough, one 12 ounce can of beer, one 5 ounce glass of wine, and one 1½ ounce shot of 80 proof liquor all contain approximately the same amount of alcohol! Some exact numbers:
The effects of alcohol on the nervous system and on driving in particular will be thoroughly discussed in the next chapter.