By Bryan Christie Edinburgh

Strong sex differences have been found in the health behaviours of school age children across Europe and North America in one of the largest surveys ever carried out into young people's health.

The study, funded by the World Health Organization, is based on interviews with 162 000 young people, aged 11, 13, and 15 in 35 countries. It found that girls are more concerned about their body size, yet boys are more likely to be overweight.

Girls in all countries reported a poorer health status than boys did. Boys drink alcohol more regularly and are more likely to use cannabis and less likely to eat fruit.

When it comes to smoking, 11 year old boys are more likely than girls to have ever smoked, but this changes by age 15: in more than half the countries studied, more 15 year old girls reported ever having smoked, particularly in western Europe.

The survey found common patterns across all countries but also uncovered huge extremes. Some of the main findings are: Only 35% of 15 year old boys and 22% of girls are participating in recommended levels of physical activity (at least one hour of moderate (or higher) intensity activity, five or more days a week). The highest proportions are in United States, Canada, the Czech Republic, and England.

Two thirds of 15 year olds and more than a third of 13 year olds have experimented with tobacco. The highest proportions of regular smokers are in Greenland, Germany, Ukraine, and Slovenia. Cannabis use is common--19% of 15 year olds reported using it in the past year.

Young people who are happy at school and get on well with their parents have the best health and are least likely to engage in risky behaviour. Dr Erio Ziglio, the head of the WHO European Office for Investment in Health and Development, said the report provided a wealth of information, much of which was not previously available in some countries. He said the WHO European Office is planning to establish a forum to bring together young people, parents, policy makers, and researchers to learn lessons from the report.

This is the fourth and by far the most detailed report in a series that began in 1983. The international coordinator of the study, Dr Candace Currie of the University of Edinburgh, said it showed important information, such as widespread sex differences in health behaviours and attitudes that need to be better understood.

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