The video that accompanies "S & M", Rihanna's recent musical offering, has the hallmarks of what we've come to expect from today's pop promos. Stockings and suspenders. Tick. Simulated sex. Tick. Sensuous eating of banana and suggestive wiping of the cream from the lips. Tick. Hard-core bondage. Tick.

Tomorrow, the Government-commissioned report into the sexualisation of children, the Bailey Review, will recommend raunchy pop videos such as these should be banned from TV before the 9pm watershed. Of all the measures mooted, this is the one most likely to attract blind fury and accusations of Mary Whitehouse-style prudishness.

But this is much more than an argument about puritanism versus free speech and self-expression. For too long, pop porn has been allowed to slip under the radar of watchdogs – because "it's only rock'n'roll", music stars and industry chiefs have ingenuously persuaded us they are above the law –and beyond responsibility – even though their biggest consumers are our children.

Sex has been a part of popular music since Elvis Presley performed his first hip thrust in the Fifties. But today's music videos are about money. The record industry has cynically used raunchiness to flog its increasingly flimsy products. While images of Christina Aguilera dancing like a lap-dancer on The X Factor are seared into our brains, few of us could name, the song she was singing.

Pop videos are one of the main ways that pornographic images get into our homes and reach very young children before they're ready to understand what they see. Some will say that every generation tut-tuts at the music of its youngsters. Yet it's the relentlessness of these images that is so damaging. Today, videos show women as porn stars, as constantly ready for sex. In the lyrics, a woman is called a "ho" or a slut.

Some of the hottest video directors are hired from porn movies. Crotch displays and butt thrusting are now the most common dance moves. One survey found that, on MTV, a sexual scene appears every six minutes. Music and porn have merged so seamlessly that in a recent TV experiment, members of the public shown stills from videos and hard-core porn couldn't tell them apart.

It is often claimed that our children don't understand what they're seeing. But you only have to see a group of nine-year-olds shimmying at a school disco to realise they get the message loud and clear. The main criticism levelled at the watershed idea is that it's impractical: there are too many outlets for music videos, from YouTube to mobile phones. But I still welcome rating music videos as a clear indication that the commercial sexualisation of children is no longer acceptable, and a message to the music industry to stop taking advantage of its core consumers.

Even if it only works on TV, this is a step towards stopping porn becoming the norm. Katy Perry or Rihanna expressing their sexual selves is fine, but their self-expression will only be seen by an audience legally old enough to have sex. But will dressing up in gimp outfits and hooker heels seem as worthwhile when the audience shrinks, because such videos are only shown after 9pm?

Ultimately though, it's up to us to parent our children. We should have already turned off the video channels in our homes. We have to reclaim our roles as first gatekeepers, and teach our children as they grow to question the sexual stereotypes these videos portray. Beyond that, they need to develop the critical faculties to judge for themselves. And that is our job – not David Cameron's.

Tanith Carey is author of 'Where Has My Little Girl Gone? How to Protect Your Daughter from Growing Up Too Soon' (Lion)