"Youth is beautiful, there's a luminosity, and that is what my eye is trained to see."

Model scout Ashley, whose job sees her travelling between Russia, China and Japan on the hunt for potential young pin-ups, is the linchpin of the acclaimed documentary Girl Model, in UK cinemas this week, which explores the lives of East European girls - some only 13 or perhaps younger - queuing up in their droves for a chance to enjoy the luxuries of a life that a successful career in front of the camera can bring.

Images we in the west see every day persuade us of the impossibly glamorous world of international modelling - Cindy Crawford on a beach, Kate Moss in boho chic, Iman looking eternally seductive through a dusky night-time haze - it all looks effortless, and the women boast a glow of confidence and security.

This film provides the bleak counterpoint, charting Ashley's increasing weariness with her role - recruiting these girls, all pretty but many worryingly blank-eyed, for agents in Russia, China and Japan.

Although she describes the benefits of her job - financially lucrative and definitely not the boredom of any normal 9 to 5 - her loneliness is palpable, travelling alone on the Trans-Siberian Railway between jobs, as well as her increasing discomfort at her role in a commercial enterprise that involves, at best a casual regard for the welfare of teenage girls, at worst, blatant exploitation of their lack of experience, options and advocacy.

It was scout Ashley herself who first approached experienced film-makers David Redmon and Ashley Sabin (not the same Ashley) and summoned them to China to see for themselves what was going on. Redmon and Sabin, with four previous films under their belt including one on post-Katrina New Orleans, were at first bemused by their invitation.

"If she is involved in all this," Redmon remembers wondering at the time, "why should we go and film that? Why is she sending us DVDs of the very same young girls? It made us both very uncomfortable."

Redmon was persuaded by his partner Sabin that it was an important thing to do, and the film-making pair set off for China first, and then Russia three times, where they followed one girl, Nadya, to Japan - "it was important for us to follow one girl all the way through and see what happened to her."

Could the documentary makers be accused of exploitation themselves, in making a documentary about young girls in bikinis? "As soon as you start watching the film and understanding the issue, you can't really enjoy it in that way, and that for me wasn't enough of a reason not to make it," explains Sabin.

Sure enough, the girls we see in the documentary themselves are lovely, vital and energetic, full of hope and ambition from the outset. But we watch them travelling alone to Japan, crying down the phone to their mothers, starving themselves on the orders of agents (who are contractually allowed to send the girls home if they gain 1cm on their waists or hips), and often somehow failing to get paid for their modelling work.

Watching Nadya and Madlen, the two main subjects of the film, at the mercy of overseas agents and clients reminded me of stories of human trafficking, just without the sex.

One of the agents looks appreciatively at the photo of a girl, soon to be 13 apparently, and ascribes to her "something an older girl wouldn’t have - dignity". This is so disingenuous as to be risible if it weren't so disturbing.

The question of blame is one that comes up often in the film - it's obviously not the girls themselves, nor their parents, nor the agents, apparently... so who then?

The filmmakers have their own ideas: 'It's definitely not one person, or one business," reflects Sabin. "In a way, we're all complicit, even consumers, because you see these images. We buy into this idea of fashion being glamorous. For me, it's not about who's to blame, it's about the amazing lack of transparency, and that's to blame - why don't we know how old these girls are?

"In the UK, there's a certain age level which is a recommended guideline within the models' equity union. And if you know how to navigate the industry, it's fine - you can make sure you're being paid enough and not exploited. But how do you know that 13-year-olds aren't getting on the catwalk or in the magazines? There's no bigger, overarching fashion industry protection. So it's possible for these businesses to do whatever they feel like doing."

"These girls want to improve their lives and that's wonderful," adds Redmon. "I'm not going to judge their dreams and their hopes. It's when people take advantage of those things, that's what makes me depressed about it all."

A bizarre postscript to the film is that scout Ashley, despite her clear self-doubt, is no longer in contact with the filmmakers, and is instead firmly back in the fold of a powerful agency in New York. "She now works at Elite Models in New York," explains Sabin. "She now mainly scouts American girls, I don't think she goes to Siberia as much."

Redmon and Sabin consider Ashley's distancing herself from the problems she herself highlighted a huge shame, as she could have been a powerful advocate for change - the stronger representation and protection that they think would improve matters - with her first-hand experience of what is really going on in some parts of the so-called glamorous world of modelling.

But the film-makers are currently not in touch with scout Ashley which, when you watch the remarkably intimate insights she was prepared to share with them on camera during the filming, seems unbelievable.

The saddest part of the film for me? The glimpse we get of teenage Nadya at home with her family in Siberia, her father hoping his daughter's career may bring in some hard-to-find pennies to improve their house. And the family tending their vegetable patch where, Nadya reflects, "for me beauty begins in nature."

Girl Model is now in UK cinemas. Watch the trailer below:

Girl Model Trailer from Ashley Sabin on Vimeo.