Widespread antibiotic use in animal agriculture is drawing increasing fire as a primary cause of the growing prevalence of drug-resistant and ever more lethal superbugs.

“There is clear evidence of the human health consequences [from agricultural use of antibiotics, including] infections that would not have otherwise occurred, increased frequency of treatment failures (in some cases death) and increased severity of infections,” the World Health Organization wrote in 2003.

Seventy percent of all antibiotics used in the United States are used promote growth or prevent infection in healthy farm animals — in other words, animals that are not showing any signs of disease.

“The heavy reliance on routine antibiotic use is a byproduct of the way we raise animals for food: packed into dim and dirty enclosures where they live amid their own filth, eat food that they haven’t evolved to digest, and are pretty much stacked atop one another,” writes columnist Ezra Klein in the Washington Post.

The food industry claims that such antibiotic use is necessary to keep food prices low for consumers.

“That really is a strange defense,” said U.S. Rep. Louise Slaughter. “We keep animals in such deplorable conditions that they’ll become sick as a dog if we don’t dose them?”

The industry’s argument is weak on financial grounds as well, Klein says. According to a study conducted by researchers at Tufts University, antibiotic resistant infections cost the U.S. health-care system $50 billion per year. In contrast, the National Academy of Sciences concluded that ending non-therapeutic antibiotic use in farm animals would raise the cost of meat consumption by $5 to $10 per person per year.

“I’d pay that for a lower risk of super-staphylococcus,” Klein writes.