UK teens are heavily exposed to alcohol and tobacco images and lyrics in digital YouTube music videos, indicates research published in the Journal of Epidemiology & Community Health.
Those exposed the most are 13-15 year olds, and girls, the findings suggest.
Relatively little attention has been paid to YouTube content, despite the fact that some music videos contain extensive alcohol and tobacco content, which is often depicted in a positive light, and that these videos tend to be most popular with younger audiences, say the researchers.
They used the results of two nationally representative online surveys of British adults and teens to calculate viewing figures for the 32 most popular music videos of top 40 chart songs in the UK during the 12 weeks of 3 November 2013 to 19 January 2014.
And they analysed the number of 10 second intervals in each of the 32 videos to estimate the total number of images/depictions/lyrics (impressions) of alcohol and tobacco content.
In all, 2068 teens aged between 11 and 18, and 2232 adults from the age of 19 onwards completed the surveys, and the results suggested that the average percentage of viewing across the 32 music videos was 22% for the teens and 6% for the adults.
The videos were available for an average of 7 to 10 months after release. And based on population census data, the researchers calculated that these delivered a total of 1006 million impressions of alcohol and 203 million of tobacco to the British population during the period between release of the video and the point of the survey.
Most of this content was delivered to 25-34 year olds, but levels of individual exposure were almost four times higher among teens, the figures indicated.
Teens aged 13 to 15 received an average of 11.48 tobacco impressions, while those aged 16 to 18 received an average of 10.5. This compares with 2.85 for adults.
Furthermore, exposure was around 65% higher among girls, with the highest numbers of tobacco impressions delivered to 13-15 year olds.
The pattern of exposure for alcohol was similar to that of tobacco, but the overall number of impressions was five times higher.
An estimated 52.11 alcohol impressions were delivered to each teen compared with 14.13 to each adult. Individual exposure levels rocketed to 70.68 among 13-15 year old girls.
"Trumpets" by Jason Derulo, and "Blurred Lines" by Robin Thicke delivered some of the highest number of tobacco impressions, while "Timber" by Pitbull, and "Drunk in Love" by Beyoncé, delivered the most alcohol content.
"If these levels of exposure were typical, then in 1 year, music videos would be expected to deliver over 4 billion impressions of alcohol, and nearly 1 billion of tobacco, in Britain alone," write the researchers.
"Further, the number of impressions has been calculated on the basis of one viewing only; however, many of the videos had been watched multiple times, so this number is likely to be much bigger," they warn.
A ban on paid-for placement of branded tobacco products has been in force since 2002 in the UK, while alcohol promotion is regulated by the Advertising Standards Authority, the Portman Group, and industry voluntary codes of practice.
But while films are classified, and TV content is subject to controls during periods when children are likely to be watching, no such regulations apply to digital music videos. The British Board of Film Classification has consulted on an age rating system for music videos made in the UK, but this does not cover tobacco and alcohol content.
Instead, it includes drug misuse, dangerous behaviour presented as safe, bad language, sex and nudity, threatening behaviour and violence.
The evidence suggests that teens exposed to depictions of alcohol and tobacco content in films are more likely to start smoking or drinking, and the researchers suggest that music videos pose a "significant health hazard that requires appropriate regulatory control."
They urge: "Owing to the obvious health implications for adolescents, we suggest that overly positive portrayals of both alcohol and tobacco in music videos should be included in both the drug misuse and dangerous behaviour presented as safe rating categories."