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Introduction

1. Facts about alcohol content of drinks

2. Alcohol metabolism

3. Predisposition to harm

4. Alcohol-related physical harm

5. Alcohol-related social and psychological harm

6. Assessment

7. Brief intervention

8. Specialist services

9. Management of specific problems

10. Prevention

11. The doctor's role

Glossary of terms

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1.  Facts about Alcohol Content of Drinks

The Unit System

The alcohol content of the various alcoholic beverages differs widely. Thus similar quantities of the various beverages can contain markedly different quantities of alcohol. The alcohol content of a given beverage is, however, easily calculated from its percentage alcohol content by volume (% ABV), which is clearly marked on the container, taking the specific gravity of alcohol into account, viz.

% ABV x 0.78 = g alcohol/100 ml

The absolute amount of alcohol in a given drink can then be calculated by reference to its volume (Table 1.1).

Table 1:1 Alcohol Concentrations in Various Beverages

Beverage Type
Alcohol by Volume
(%) ABV
Alcohol Content
(g/100ml)
Beers/lagers/stouts/ciders
alcohol-free
<0.05
0.04
low alcohol
0.05-1.2
0.4-0.9
standard strength
3.0-4.0
2.3-3.1
premium srength
5.0-6.0
3.9-4.7

super strength

8.0-11.0
6.2-8.6
Alcopops
5.0-6.0
3.9-4.7
Wines
5.0-13.0
3.9-10.1
Fortified Wines
sherry, vermouth, cinzano
14.0-20.0
10.9-15.9
Spirits
light (gin, vodka, white rum)
37.5
29.3
dark (whisky, brandy, dark rum)
40.0
31.2
Liqueurs
14.0-40.0
10.9-31.2

 

In order to simplify the quantification and hence to facilitate assessment of alcohol intake, a system, based on defining quantities of beverages containing equivalent amounts of alcohol has been devised for use in Great Britain. A 'unit' of alcohol is the amount contained in 1/2 pint (284 ml) of beer, a single glass (125 ml) of table wine, a single glass (50 ml) of fortified wine, for example sherry, or a single measure (25 ml) of spirits; it approximates to 10 ml or 8 g of absolute alcohol.

Inaccuracies of the Unit System

This system is now used widely by the lay public, by 'alcohol agencies' and by physicians alike. As currently publicized, however, it is greatly over-simplified.

  • the alcohol content of beers and lagers varies considerably (see Table 1.2) so that a pint of beer (568 ml) may contain from 2 to 5 units of alcohol depending on its strength
  • second, beers and lagers, particularly for off-licence consumption, are sold in cans, in volumes varying from 330 to 440 or 500 ml, which bear little relationship to the pint measure
  • there is no standardized measure for wine; a 'glass' may contain from 4 to 12 fluid ounces (114 to 342 ml) and so, depending on the alcohol content of the wine, from 0.6 to 4.5 units
  • until recently the standard 'pub' measure of spirits varied from 1/6 to 1/4 gill (24 to 37 ml) by region; European Community directives have now ensured that the measure is standardized to 25 or 35 ml
  • measures of drinks consumed at home differ from 'standard' measures; beer is consumed from bottles or cans in varying volumes, wine measures tend to be larger while measures of spirits tend to exceed optic measures by a factor of 2.5 to 3.0
  • the unit system is essentially parochial and does not lend itself to international comparisons; thus, in Australia and New Zealand, a 'standard' drink contains 13 ml or 10 g of absolute alcohol while in the United States of America, a 'standard' drink contains 15 ml or 12 g of absolute alcohol.

Improving Accuracy

The accuracy of the 'unit' system can be improved by taking differences in beverage strengths and volumes into account. Thus, the exact number of units of alcohol in a given beverage volume can be calculated from the % ABV using the information that 10 ml of absolute alcohol is equivalent to 1 unit of alcohol. Thus the number of units of alcohol in a given volume of beverage equals:

A half-litre can of 8% ABV lager contains 4 units of alcohol ; likewise, a 750 ml bottle of 13% ABV wine contains 9.8 units of alcohol (Table 1.3).

Newer Drinks

In recent years new ranges of fortified wines, such as MD 20/20 and Mad Dog, strong white ciders, such as Diamond White and Ice Dragon, fruit-flavoured lagers and ciders, such as Desperados and Maxblack and alcoholized soft drinks, the co-called 'Alcopops', such as Hooch alcoholic lemon, have been marketed. The fortified wines have sweet fruit flavours such as cherry, banana and strawberry and a % ABV of between 13 and 21%. The white ciders, which are filtered to remove colour and some flavours, have a % ABV of between 8 and 9%. The lagers and ciders which are additionally flavoured with citrus fruits or blackcurrant and the 'Alcopops' which are essentially soft drinks which have been 'fortified' with alcohol have a % ABV of between 5 to 6%. These drinks are attractively packaged, often in small volumes, which may nevertheless contain several units of alcohol. Their obvious appeal to young people has become a focus of public concern.



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