Alcohol can be made by four different methods:

• Fermentation of fruit or grain mixtures (beer, wine). See How Beer Works for details.
• Distillation of fermented fruit or grain mixtures (spirits such as whiskey, rum, vodka, gin are distilled),
• Chemical modification of fossil fuels such as oil, natural gas or coal (industrial alcohol)
• Chemical combination of hydrogen with carbon monoxide (methanol or wood alcohol)

The alcohol found in alcoholic beverages is ethyl alcohol (ethanol).

Alcohol, also called Ethanol, Grain Alcohol, ethyl alcohol, the most important member of a class of organic compounds that are given the general name alcohols; its molecular formula is C2H5OH. It is the intoxicating ingredients of many beverages produced by fermentation.

There are three main processes for the manufacture of ethanol: the fermentation of carbohydrates, the hydration of ethylene, and the fermentation of acetaldehyde (commonly prepared by the hydration of acetylene). Before 1930 all ethanol was prepared by fermentation process, which still remains the most important method in most countries. In the United States, 70 to 90 percent of the total output of ethanol is now produced by hydration of ethylene, however. The fermentation process involves the transformation of carbohydrates to ethanol by growing yeast cells. The chief raw materials for this process are molasses and corn (maize). The hydration of ethylene is achieved by passing a mixture of ethylene and a large excess of steam.

Ethanol produced either by fermentation or by synthesis is obtained as a dilute aqueous solution and must be concentrated by fractional distillation. Direct distillation can yield at best the constant-boiling-point mixture containing 95.6 percent by weight of ethanol. Dehydration of the constant-boiling-point mixture yields anhydrous, or absolute, alcohol. Because ethyl alcohol for beverage purposes is subject to tax in all countries, ethyl alcohol for industrial purposes must be rendered unfit to drink (denatured) to escape taxation. Typical denaturants that are mixed with ethyl alcohol are methanol, camphor, benzene, and kerosene.

Pure ethanol is a colourless, flammable liquid (boiling point 78.5� C [173.3� F]) with an agreeable ethereal odour and a burning taste. Ethanol is toxic, affecting the central nervous system. Moderate amounts stimulate the mind and relax the muscles, but larger amounts impair coordination and judgment, finally producing coma and death. It is an addictive drug for some persons, leading to the disease alcoholism.

Ethyl alcohol is converted in the body first to acetaldehyde and then to carbon dioxide and water, at the rate of about 0.75 ounce per hour; this quantity corresponds to a dietary intake of about 200 calories.

Alcoholic drinks consist mainly of flavouflavoured water and ethyl alcohol (ethanol). They are made by the fermentation of fruits, vegetables or grains. Beer, lager and cider are usually about one part ethanol to 20 parts water although some brands may be twice as strong as others. Wine is about twice to four times as strong and distilled spirits such as whisky, rum and gin are about half water and half ethanol.

The unit of alcohol measure is used to determine medical guidelines as to what are supposed to be safe levels of drinking for men and women per week. These guidelines have recently changed.

In 1986 these were 50 units a week for men and 35 for women. Suggested figures were lowelowered to 21 units a week for men and 14 units for women but have now been increased again to 28 units for men and 21 units for women. There is controversy about how 'scientific' these figures are and some people have suggested regular, moderate drinking may even help prevent heart attacks.

One unit of alcohol is equivalent to:

• Half a pint of beer, cider or lager
• 1 single spirits
• 1 glass of wine
• 1 small glass of sherry
• 1 small glass vermouth

Making and drinking alcohol goes back many thousands of years to the earliest days of civilisation. This probably first happened in the Middle East where grapes grow wild without cultivation. Alcohol is mentioned in the Old Testament when Noah plants a vine yard after the Flood and becomes drunk. The evils of getting drunk are recorded on Egyptian papyrus from 3500BC. The population of ancient Greece was noted for heavy drinking. In ancient Rome getting drunk was almost a national pastime, and it was an offence to be drunk in charge of a chariot.

Many societies and religions have allowed the use of alcohol. The Roman Catholic and Jewish religions include wine in their ceremonies.However, the Islamic faith (Muslims) and some Christian groups such as the Mormons do not allow the use of alcohol.

For centuries 'ale houses' and beer drinking have been a part of everyday life in Britain. Because of the lack of pure drinking water, beer was commonly the main drink to have with a meal.

The manufacture, sale, distribution and purchase of alcohol is mainly controlled by the 1964 Licensing Act.

There are different licences governing the sale of alcohol. Full 'on licenses' are granted to pubs and clubs and mean alcohol can be drunk on the premises. 'Off licenses' are granted to off- licenses, shops and supermarkets where alcohol cannot be consumed on the premises.'Restaurant licenses' permit the sale of alcohol and consumption on the premises if accompanied by a meal. Licensing laws also restrict the times at which alcohol can be sold and consumed.

There are also rather complex laws about the age at which people can drink alcohol:

1. It is an offence to give alcohol to a child under 5 years old.
2. Children of any age can go into parts of pubs that are set aside for meals or as family rooms.
3. Children aged over 14 years can go into pubs unaccompanied by adults but cannot be served alcohol until they are 18 years old.
4. Young people are not allowed to drink alcohol in a bar or buy alcohol in a pub or off licence until they are 18 years old.
5. 6 year olds can buy and drink beer or cider (but not spirits) in a pub but only if they are having a meal.
6. There are slightly different rules in different parts of the UK. In Northern Ireland, for example, nobody can enter any part of a pub if they are under 18 years old.

In order to understand alcohol's effects on the body, it is helpful to understand the nature of alcohol as a chemical, so let's take a look...

Here are several facts:

• Alcohol is a clear liquid at room temperature.
• Alcohol is less dense and evaporates at a lower temperature than water (this property allows it to be distilled -- by heating a water and alcohol mixture, the alcohol evaporates first)
• Alcohol dissolves easily in water.
• Alcohol is flammable (so flammable that it can be used as a fuel).

Alcohol is absorbed into the bloodstream and starts to have an effect within 5 to 10 minutes. The effect can last for several hours, depending on the amount consumed. The effect will also depend on:

1. How quickly it is drunk, whether there is food in the stomach and the person's body weight.
2. How used to drinking someone is, in other words, what their tolerance is to alcohol.
3. How people feel before they are drinking. People who feel relaxed and in a good mood are less likely to become aggressive. Some people 'drown their sorrows' in drink and find they feel worse than ever after.

After about two pints of beer most people feel less inhibited and more relaxed. Alcohol is a depressant drug. It acts on the central nervous system to slow the body down. Some people become aggressive and argumentative, especially men. A lot of violence on the streets and in the home (much of it directed at women and children) happens after people have been drinking.

After about 4 pints of average strength beer, drinkers become uncoordinated and slur their speech.

Drinking alcohol makes accidents more common, especially when people fall over, drive or are operating machinery. Lowering of inhibitions can make it more likely that people will put themselves in sexual situations which they later regret. They are also less likely to practice safer sex and use condoms if they have intercourse. Drinking too much in one go can lead to losing consciousness and death by choking on vomit.

Alcohol can also be very dangerous to take in combination with other drugs, especially other depressant drugs such as barbiturates, heroin, methadone or tranquillisers and drugs such as anti-depressants, anti-histamines and painkillers. Mixing these drugs and alcohol has led to many fatal overdoses.

Long term, heavy drinking can be very damaging. Physical dependence and tolerance develop so people drink more and more and suffer withdrawal symptoms (such as trembling, sweating, anxiety and delirium) if they try to stop. At this point people will be regarded as alcoholics. Heavy, long term drinking can also lead to damage to the heart, liver, stomach and brain and lead to obesity.

Pregnant women who drink six of more units of alcohol a day may give birth to babies who suffer withdrawal symptoms and also have facial abnormalities and possible retarded physical and mental development which together is called foetal alcohol syndrome. However such cases are rare in the UK. Lesser degrees of drinking during pregnancy may result in a baby being born with a low birth weight but there is little evidence that moderate drinking during pregnancy causes harm to the mother or her baby.

Excessive drinking commonly aggravates personal, family, work and financial problems and contributes towards family breakdown, violence and other forms of crime associated with loss of control.

Between 20-50,000 deaths a year in the UK are associated with alcohol. This includes deaths from alcohol related accidents, cirrhosis of the liver and other diseases and death from overdose.