While the most commonly known use of antibiotics is to kill bacteria fight off sickness, for the past 60 years they've also been given to healthy farm animals to promote growth and prevent disease, CBS' Katie Couric reported.
But this practice is increasingly putting people's health at risk, and the FDA is now saying the overuse of antibiotics in animals has to stop, Couric said.
For one, there have been numerous cases of MRSA, drug-resistant bacteria, hitting farm workers who handle animals:
A University of Iowa study last year, found a new strain of MRSA -- in nearly three-quarters of hogs (70%), and nearly two-thirds of the workers (64%) -- on several farms in Iowa and Western Illinois. All of them use antibiotics, routinely. On antibiotic-free farms no MRSA was found.
And it's not only those who handle livestock who are in danger-- the bacteria could spread in many ways, from the food supply to water runoff in farms, Shelley Hearne, managing director of PEW health group, said.
WATCH how antibiotics in animals can pose a threat to human health:
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