Little agreement exists between countries on what is considered safe or sensible alcohol consumption, a comparison of drinking guidelines by British researchers has found.
Psychologists from the University of Sussex looked at government advice on drinking in 57 countries, including all 27 EU member states.
Dr Richard de Visser and Nina Furtwangler found a "remarkable lack of agreement" about what constitutes harmful or excessive alcohol consumption on a daily and weekly basis, and when driving.
There was also no consensus on whether it was safe for women to drink as much as men, their study, published this month in Drug and Alcohol Review, found.
Dr de Visser said: "We were surprised at the wide variation in guidelines. There is no international agreement about whether women should drink as much as men or only half as much.
"In some countries, the weekly maximum is simply seven times the daily maximum, whereas in others there is an explicit statement that drinkers should have at least one alcohol-free day a week."
Calls have now been made for internationally-agreed standard definitions of alcohol units and consumption guidelines to help people drink responsibly.
The research found that some countries referred to standard drinks but failed to define them in grams of ethanol. In addition, eight of the 27 EU member states did not have readily accessible guidelines.
Among the countries that allowed drivers to have alcohol in their blood, there was a ten-fold variation between the least generous, Panama, and the most generous, United Arab Emirates.
Dr de Visser acknowledged that guidelines have limited success in encouraging moderation.
But he added: "Despite these caveats, it is important for people who do want to adhere to recommendations to drink responsibly, that there should be internationally-agreed standard definitions of alcohol units and consumption guidelines.
"Agreed guidelines would be useful for international efforts to reduce alcohol-related harm by increasing people's capacity to monitor and regulate their alcohol consumption."
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