Ah, journalistic integrity, how we love you.
Quite aside from the concerns expressed in the thread, it turns out that if you look at the actual study, rather than just The Telegraph BS article, the results are somewhat different. The Telegraph, of course, doesn't mention that at all.
On pages 63-64 of the study, there are TWO sets of answers to the same list of questions. The first covers all teenagers in the survey, a total of 2136, while the second covers the answers of sexually active teenagers only, a total of 713. All of the figures cited in The Telegraph are from the second list.
Sending sexually explicit text messages? 72% of sexually active teenagers, but only 42% of all teenagers.
Sending naked or semi-naked photos or videos of themselves? 50% of sexually active teenagers, but only 26% of all teenagers.
Have received sexually explicit messages by phone or email? 84% of sexually active teenagers, but only 54% of all teenagers.
Don't forget that 'all' teenagers includes 'sexually active teenagers'. The results do not suggest, for example, that 42% of non-sexually active teenagers have sent sexually explicit text messages. Those figures are not given.
Now, you may still think that the 'all teenagers' figures are too high, and you may still think that the 'everyone is doing it so it's fine' suggested in The Telegraph article is dangerous. But the fact is that The Telegraph article picks the most sensationalist results, and then doesn't explain what they actually mean, and that they relate to a subset of the group being surveyed.
Here's the link to the original study, by the way. The Telegraph doesn't provide the link, but it does link to an article on The Times, which although behind a pay wall, happlily has the link in the first paragraph... Yeah, Pulitzer Prize winning stuff, this.
http://www.latrobe.edu.au/__data/assets/pdf_file/0005/576554/31631-ARCSHS_NSASSSH_FINAL-A-3.pdf
EDIT: I should note that The Times article, or what I can see of it, seems much better, saying "Seven in every ten sexually active 15 to 18-year-olds have sent explicit text messages..."