Campaigners say girls are encouraged to copy provocative images and young males react by treating them as sex objects, putting girls more at risk of sexual assaults and domestic violence.
Dr White said parents had a key role to play. 'There's an increasing sexualisation of children. When you see a little girl wearing a T-shirt with a Playboy bunny, that's wrong isn't it? I've seen another that said "Porn star in the making".
'Music videos are extremely influential,' she added.
There was outrage over Britney Spears's video for Hit Me Baby One More Time, which featured her in seductive poses while wearing school uniform.
Dr White said the changing attitude to young girls had an effect on potential abusers, too. 'I think it's all subconscious and there's a drip, drip, drip effect. All together it's having an effect on values.
'For the potential perpetrators, it's about knowing what's acceptable and what's not acceptable.'
St Mary's is Britain's long-estestablished sexual assault referral centre. It opened in 1986. There are now 28 around the country, with eight more planned.
Earlier this year the Government launched a study into the issue, led by psychologist Dr Linda Papadopoulos.
She said she is looking at whether 'there is a link between exposure to these images and boys' expectations about acceptable sexual behaviour'.
