A Tesco supermarket sign in London. The chain acknowledged that its low-cost beef lasagna had in fact been 60 percent horse.

LINDA WERTHEIMER, HOST:

Britain's environment secretary arrives in Brussels today, for an emergency meeting on a widening scandal about horsemeat. European Union ministers want to know just how horse meat and pork found its way into processed beef products and how to stop that practice. As Vicki Barker reports from London, Britain appears to be hardest hit by this scandal so far.

VICKI BARKER, BYLINE: Britons had just sat down to their evening meal when the latest revelation broke: The Tesco supermarket chain admitted that its low-cost beef lasagna, pulled off the shelves last week after testing positive for horse DNA, had, in fact, been 60 percent horse.

Officials insist the adulterated meat poses not threat to human health. Food-safety campaigners aren't so sure. Some horses are given a powerful and dangerous veterinary drug called phenylbutazone, or bute. The fear that unscrupulous processors prepared to adulterate beef with horse might also be prepared to buy horses without valid health certificates.

But food law expert Michael Walker claims any threat from bute is vanishingly small.

MICHAEL WALKER: If it is found, it will be present, if at all, at parts per trillion levels, very low amounts. And the risk there is very low.

BARKER: British regulators have been accused of doing too little, too slowly. Ten weeks to get a test result on a food product, and when the crisis first broke they admitted they hadn't actually tested for horse in 10 years. But the government's point man in the crisis, Environment Secretary Owen Patterson, told British lawmakers it's the Tescos and the Burger Kings that need to be testing more, not regulators.

OWEN PATTERSON: The prime responsibility for dealing with this, lies with retailers and food producers, who need to demonstrate that they've taken all necessary actions to ensure the integrity of the food chain in this country.

BARKER: One thing the scandal has shown, though, is just how long and winding that food chain really is, and how little oversight is exercised within Europe's open borders. Stores in Ireland, France and Sweden have also had to pull suspect products off their shelves.

Here in Britain, the adulterated meat has been traced to big processing plants in Ireland, France and England and they may have bought it from suppliers as far away as Poland and Romania. At least one plant owner has claimed he was pressured to get ground beef from Eastern Europe to keep prices low.

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UNIDENTIFIED MAN: There we go. That one's 11.30.

BARKER: There have been some beneficiaries of this crisis: local British butchers. Lee Mullett casseroles an organic free range chicken. Speaking across the counter in his shop in Chiswick, West London, he says he's seen a trickle of new customers and has fielded some penetrating questions from old ones.

LEE MULLETT: For our customers, it's what they're always concerned about: It's about provenance. It's about where the meat comes from, and what it's fed. They want to know that there's no drugs, no additives, no nasties, and what they're buying is what it's supposed to be.

BARKER: But Mullett says the public tidal wave of revulsion over the thought of inadvertently eating their beloved horses has generally not sent people up market. He says the vast majority of his fellow Brits really don't seem to care what's in their burgers, meatballs or lasagna - as long as they're cheap. For NPR News, I'm Vicki Barker in London.

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