Organic broiler chickens are three times as likely as conventionally-bred poultry to be contaminated with a bacterium that causes food-poisoning, say Danish vets, the New Scientist reports this week. The team at the Danish Veterinary Laboratory in Aarhus found that all 22 organic broiler flocks they investigated were infected with Campylobacter - the most common cause of food poisoning in the UK. Only one third of 79 conventional broilerhouses were infected. "The organic movement is sound, but this is unwelcome news," says Karl Pedersen, who supervised the project. He says the result is not entirely surprising, since organic birds are allowed to roam outside and are more likely to be exposed to food and water contaminated with infected faeces from wild animals. "But it turns out that the difference was far higher than we expected," he claimed. Conventionally-bred birds are slaughtered after around 38 days, whereas organic birds live twice as long, and so are more likely to pick up infections. And in most European countries, conventional broiler farmers grow and slaughter all their chickens at the same time, so empty broilerhouses can be thoroughly disinfected before the next batch of day-old chicks arrives. Campylobacter is the most common cause of food poisoning in Britain. Although infections have levelled out over the past few years, cases have doubled since 1986, from 25,000 to 54,000 in 2000. Pedersen says that there is little that can be done to prevent infection if birds roam freely outside. He says the bacteria will not survive cooking, but could spread to other food items if contaminated carcasses are unhygienically handled in the kitchen.