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Caging Hens Poses Serious Public Health Threat

Salmonella is the leading cause of food-related U.S. deaths

The Humane Society of the United States

chickens crowded in a battery cage

A bill to improve the lives of egg-laying hens (seen above in barren battery cages where the birds can't even spread their wings) enjoys considerable support from newspaper editorial boards across the country. photo: Compassion Over Killing

Every year, the egg industry is responsible for an epidemic of human disease. "Egg-associated illness caused by Salmonella is a serious public health problem," the U.S. Food and Drug Administration wrote in a 2009 press release. The FDA estimates that Salmonella-infected eggs sicken 142,000 Americans annually. In fact, Salmonella is the leading cause of food-related deaths in the United States.


One reason millions of Salmonella-infected eggs reach American supermarkets every year is the mistreatment of hens by the egg industry. Cramming 100,000 birds or more under a single roof in tiny battery cages creates an immense volume of contaminated airborne fecal dust that can rapidly spread Salmonella infection between the birds.

In Europe, where these intensive confinement systems are being banned, 30,000 samples from more than 5,000 egg operations across two dozen countries were taken to compare the Salmonella risk between battery cage operations and cage-free farms. Without exception, for every subtype of Salmonella reported and every type of production system examined, there was a significantly lower risk of Salmonella infection in cage-free production.

A European Food Safety Authority analysis of the data found that factory farms caging hens had up to 25-times greater odds of Salmonella infection than cage-free farms.


More Evidence

Since the European investigation was published, there have been seventeen additional studies published in the peer-reviewed scientific literature comparing Salmonella risk between caged and cage-free flocks. Without exception, each of the eighteen found a higher rates of Salmonella in typical battery cage production units [[1],[2],[3],[4],[5],[6],[7],[8],[9],[10],[11],[12],[13],[14],[15],[16],[17],[18]]. A study published in the December 2009 issue of Poultry Science even found that cage-free hens experimentally infected with Salmonella may clear the infection faster than caged hens.

An article in the trade publication World Poultry entitled "Salmonella thrives in cage housing" acknowledged that "the majority of the studies clearly indicate that a cage housing system has an increased risk of being Salmonella-positive in comparison to non-cage housing systems."

The United Egg Producers, the U.S. egg industry trade group, claims to base its assertions on science but, like the tobacco industry before it, the egg industry appears willing to twist the facts regardless of the human cost. The UEP claims that caging hens is "safer for food safety" but, following the landslide vote in California to ban the practice, the industry was forced to finally come clean with the dirty truth: the editor-in-chief of the trade journal Egg Industry admitted that such claims are "invalid and unsupportable."

The science is clear: Caging hens means more Salmonella, which means more human illness. A 2002 study published in the American Journal of Epidemiology found that people who ate eggs from caged hens had about twice the odds of coming down with Salmonella food poisoning compared to those who did not eat cage eggs.

How many more sicknesses, hospitalizations, and deaths will it take for the U.S. egg industry to modernize its production to safer, higher welfare cage-free systems?

Keep yourself safer and spare animals suffering by learning to eat more humanely and trying new alternatives to eggs.

Study citations updated May 5, 2011.

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