Rachel Cooke meets Eric Schlosser, author of Fast Food Nation

Eric Schlosser, author of the best-selling Fast Food Nation, is about the most gentle and unassuming man you could hope to meet. Even when he's talking about the stuff that makes him really mad - the continuing exploitation of immigrant workers by the American meat-packing industry, say - his tone is always mildly perplexed rather than enraged, forensically precise rather than emotively passionate. But there is one thing he can't much stomach, and that's journalists who insist on taking him out to lunch at McDonald's. When his book came out six years ago, this was a regular occurrence. Thrilled by their interest in his work, he went along with their desire to see him perched at a Formica table, taking in the soulless sights and sounds of the mighty chain with which he found himself locked in desperate combat. No longer. Before I meet him, it's made clear to me that, if at all possible, Schlosser would rather dine at a real restaurant: you know, one with cutlery and napkins, and meat that comes from just the one animal rather than several hundred.

Well, thank God for that. I was not exactly a hearty consumer of cheeseburgers before Fast Food Nation was published. Once I'd read it, however, my interest in eating such things didn't just dwindle: it disappeared. I had only to pass a McDonald's or Burger King to feel physically sick. Like lots of people, I became oddly preoccupied with the fact that a fast-food strawberry milk shake contains nearly 50 chemicals, or that Chicken McNuggets used to be injected with beef additives to give them flavour. Schlosser's book, a gripping (and envy-inducing) piece of muck-raking that more than stands up to comparison with the work of Upton Sinclair, is full of horror: of blood, sweat and lost limbs. It also, memorably, included the fateful and disgusting news that some of the meat used to make America's burgers literally contained shit - a revelation that marked the beginning of a movement that has seen fast food chains finally lose a little of their immense power. These companies feared and despised Schlosser, and did all they could to discredit him (though they would never agree to meet him face to face). But none sued. He lived to tell the tale - and to eat lunch in halfway decent restaurants.

So here we are, in King's Cross, at Konstam at the Prince Albert, a restaurant that uses only seasonal ingredients, and somehow manages to source all of them from inside the M25: pork from Amersham, carrots from Brick Lane, honey from Tower Hill. It's as far from being McDonald's as my guest is from being Kitty Kelly. Schlosser is in London to promote the movie of Fast Food Nation, which he has co-written with the film's director, Richard Linklater (Slacker, Before Sunrise, School of Rock), and which has a glammy cast that includes Patricia Arquette and Ethan Hawke. Before I saw it, I wondered how it had been possible to get such a film made; I assumed the movie would be a documentary, and couldn't fathom how the notoriously secretive companies Schlosser attacks could have been portrayed on screen. In fact, he and Linklater have largely put aside his book, using drama rather than fact to score the same points. The film is set in Cody, Colorado, whence Don Henderson (Greg Kinnear), an executive at a chain called Mickey's, has been sent to investigate how contaminated meat has got into the company's burgers. Here, he crosses paths with - though he never really sees - the illegal Mexican immigrants who daily risk their lives to process the meat; the ruthless bullies who run the meat-packing plants; the bored teenagers who staff Mickey's to pay for school; and the small farmers whose livings have ceased to be sustainable in the face of sweeping industrial agriculture. On paper, this might sound a touch preachy. In fact, save for its frustrating lack of a proper ending, it is compelling (though you probably won't feel like dinner afterwards).

'When the book came out, I was approached by lots of documentary companies,' he says. 'It seemed logical. But this was before Bowling for Columbine. There was no theatrical release market for documentaries. So I was being approached by the TV networks and, while I liked the film-makers, I didn't trust what would happen in the end. Not even PBS [America's public broadcasting service]: they're partly funded by McDonald's. So I decided: no film. But then I was on a book tour in Austin, Texas, and I met Rick Linklater. We're roughly the same age [late forties], our sensibilities are similar. So after talking for two years, we went ahead, financed without studio involvement to avoid last-minute interference. It takes people that you never see, and puts them on screen. It's a character study, and I'm proud of it.'

Yes, but it's so bleak! 'Yeah.' Schlosser smiles. 'But to make it otherwise would have been a lie. We could've had Greg Kinnear's character going before Congress, testifying against the industry. We could have had the workers rallying. Except, in the US, you won't see any of that happening. A lot of well-intentioned people are complicit with things that aren't very nice at all. I don't want to sugar the pill. Things are really bad in the US just now.'

But wasn't his book supposed to have made things better? Hasn't Ronald McDonald been busy flogging salads, and closing franchises? Another quiet Schlosser smile. There are two sides to this story. 'McDonald's wasn't doing that well,' he says. 'Though the World Cup helped them a lot. What is good is that, since Fast Food Nation came out, there has been a shift in awareness, primarily among the middle classes. They want to know where food comes from. The rise of organics, celebrity chefs ... I know some of it is irritating, but some of it is good. But what hasn't changed is the diet of the poor. Remember smoking? When the middle classes started to give up, the tobacco companies focused their attention on the urban poor, and on developing countries. That's what the fast food companies are doing. In the US, they're heavily targeting African American and Latino customers. There's all this talk about salads, but in the US, there's also the dollar menu. In the last three years, McDonald's has seen a 33 per cent revenue growth thanks to that. Their huge push now is in China. There's not a great tradition of eating beef there; they favour poultry, which is why KFC is more successful. So McDonald's ads are aimed at young men, and connect hamburger consumption with virility. It's about potency, about women being drawn to men who eat beef. Meanwhile, in the US, they're labelling trans fats. Now, you're kidding yourself if you see such changes as being driven by moral or ethical concerns. They happen only when the company is under pressure.'

But if a few garden salads with ranch dressing do not a more skinny and healthy nation make, what of the other practices exposed in his book? The contamination of meat; the fact that, in the meat rooms, so many people lost so many limbs; or that those injured were made to sign away their right to sue forever for fear of not being able to pay their immediate medical bills. 'Well, McDonald's and Jack in the Box [another American chain] have introduced tough new safety rules for their suppliers, which involves continually testing the meat. That's good. The bad thing is that these are entirely private initiatives, so there's no way to know what the test results are. When you have industries policing themselves, it would be nice to think that they're doing a good job, but how do we really know? There hasn't been a huge outbreak of E.coli in meat in the US in a few years, but there's been salmonella.' He also points to the some 200 people who, in 2006, fell ill in 20 states after contracting E.coli from contaminated, pre-packed spinach, as evidence that this particular story is not over yet. 'Eighty per cent of American spinach comes from California, and one big sink is effectively washing it all. Unfortunately, chlorine doesn't kill E.coli. The industrialisation of agriculture is having unexpected consequences.'

As for the human consequences of America's rapacious meat-packing industry, Schlosser believes that in this area at least there is no doubt: things are much worse. 'The Bush administration is totally supported by the meat-packing industry, and the industry is essentially writing the laws.' He points out that the current chief of staff at the US Department of Agriculture was, until 2001, chief lobbyist for the National Cattlemen's Beef Association, and notes two changes as having special significance. First, the fact that the industry has got rid of the ergonomics standard, designed to prevent cumulative trauma injuries, against which it had been fighting for years. Second, the fact that in 2002, it changed the documentation that must be filled out in a slaughterhouse when injury occurs. In 2001, the meatpacking industry had the highest rates of injury in America - about three times higher than the national average for factories, despite widespread under-reporting of slaughterhouse injuries. The rate of cumulative trauma injury (such as carpal tunnel syndrome) was 33 times higher. Today, it's all but impossible to tell how many people are still getting hurt. The Occupational Safety and Health Administration altered the form used to record injuries, thus miraculously 'reducing' them by 50 per cent. Certain more minor injuries no longer had to be noted at all. 'And they put out a press release celebrating it!' he says, with a slow shake of his head.

And so it goes on. Schlosser recently wrote a piece for The Nation about the plight of workers at the Smithfield Packing Company in Tar Heel, North Carolina - the largest hog slaughterhouse in the world. Working conditions at Smithfield are reportedly so extreme, even the federal government has criticised it. According to the United States Court of Appeals, Smithfield had, over a period of time, violated a variety of labour laws and created 'an atmosphere of intimidation and coercion' in order to prevent workers at the plant from joining a union. Between 2000 and 2005, the chief of security at the slaughterhouse, who carried handcuffs and a gun, ran a company police force that arrested almost 100 workers. Mexicans were always given the worst jobs, often working alongside prison inmates on work release. As an investigative reporter who worked there undercover put it: 'The Smithfield plant will take just about any man or woman with a pulse and a sparkling urine sample, no questions asked.' As Schlosser points out, it is almost impossible to believe that it is 100 years since Sinclair published The Jungle, the original account of greed and exploitation in the meat-packing industry. For so very little seems to have changed.

Schlosser never meant to become an activist - and though he is still more than happy to address, say, the Soil Association, he is also keen to remind me that he is now deep into a book about the US prison system. He grew up in New York, where his father was chairman of the NBC network, and read history at Princeton. Having tried his hand at both novels and plays, he then worked in the film industry, writing scripts with some success. But he wasn't happy. So he became a journalist: Fast Food Nation grew out of a pair of articles he wrote for Rolling Stone. He is a meticulous researcher and interviewer, and his writing, for all that it often ends up being a call to arms, shows the steady, becalming influence of John McPhee, whose non-fiction writing course, The Literature of Fact, Schlosser took at Princeton. Celebrity does not interest him at all; he seems to be motivated solely by finding stuff out. For this reason, he was more than happy to pass the fast-food baton - I picture it as a huge submarine roll stuffed with pastrami, Monterey Jack cheese and watery tomatoes - to the likes of Morgan Spurlock, star of Super Size Me, and Greg Critser, author of Fat Land

How will the film go down with his enemies? 'Lots of companies in the US make use of this whole shadowy network of spies, though I console myself that my office is such a mess, they'd never be able to understand my filing system. When the book came out, these crazy groups emerged out of the woodwork that were surrogates for the fast food companies. At book readings, there were people who had clearly been planted in the audience. There were letter-writing campaigns, and campaigns to stop me speaking at schools. It made life very unpleasant. Have my phone records been copied? Am I under surveillance? I've no idea, but I think about it. It's crazy. I mean, what have I done? I've criticised a company that makes hamburgers, that's all. McDonald's has spent $18 million-$20 million on marketing alone since my book came out. My book, even this film, is nothing compared to that. They should be able to tolerate criticism.'

In response to the film, McDonald's in Australia has already run an ad campaign urging consumers to: make up their own minds. 'It's disingenuous. There's a kid saying: "I heard there's no meat in hamburgers ... let's go find out." He finds the cattle, and then he says: "I'm not going to listen to other people any more." But I never said there wasn't meat in them. I just want to know where that meat is coming from.' Schlosser is not, and never has been a vegetarian.

You might imagine that, in the face of all this, the man who brought us Fast Food Nation would find it hard to get out of bed in the morning. But not a bit of it. 'Oh, I feel optimistic,' he says, finishing his Mersea sea bass. 'I always do. I think there are limits as to how far shopping can change the world, and I never tell people what to think. But what I would say is: open your eyes. Don't lead a life that's unexamined. Realise that how you spend your money has a ripple effect. If you eat or shop in a certain place, that's like a vote - a vote for what they're doing. You're supporting that business. So be conscious and informed and give your money to the people who are doing things the right way. Open your eyes. Mine are wide open.' As he tells me this, Schlosser has the benign look of one who leads a good life, or has eaten a good lunch, or perhaps both - since in his eyes at least, they amount to pretty much the same thing.

· Fast Food Nation is released on 24 March

Thanks to guardian.co.uk who have provided this article. View the original here.