The Observer. Hello, it's Ada here and you're listening to the slow newscast from The Observer. In the

1950s, the first major medical reports linking smoking to lung cancer were published.

It was seismic, revealing an industry built on addiction that caused direct harm to individuals.

But it was the media that caused a shift in attitudes.

One of the most popular magazines at the time, The Reader's Digest, published an article, Cancer by

the Carton, which is widely considered to have led to a steep drop in cigarette sales.

But it would then take more than a decade for health officials to act, with warnings on packaging

not coming until halfway through the 1960s. The response of governments was far too slow. Fast forward to now and experts

are warning that history is repeating itself, not with cigarettes this time, but with social media.

The impact it has on children's mental health is widely documented, but the harms potentially

caused by the tech platforms arguably go even further.

This week, my colleagues Rachel Sylvester and Matt Russell ask,

what exactly are children watching online and how is it affecting them?

Over to Rachel.

So when it's initially dropped, this red versus blue street fights... Earlier this year, there was talk across TikTok and Snapchat of a set of violent battles between schools.

There has to be a joke. There's no way this is real. Someone should put in our leg, like, got you now.

Oh, got you now.

Originally in Hackney in East London, it quickly spread across the capital.

Because we have time to war.

If you want to war, go on Fortnite and do it.

Do you what I mean?

Parents were getting letters from schools, warning about the potential threat of violence.

...