Considering that 80% of all antibiotics sold in the U.S. are used on farm animals, and that most of those drugs are used primarily for growth promotion, you’d think we’d be happy to see a state like California introduce legislation that appears to ban the use of antibiotics to get fatter cows, pigs, and chickens. But it’s what that bill doesn’t do that has us concerned, and why California Governor Jerry Brown has vetoed it.

State Senate Bill 835 [PDF] would forbidden the use of antibiotics specifically for growth promotion. It would also require any antibiotics given to animals be prescribed by a veterinarian.

The bill is basically identical to the FDA’s 2013 guidance; the only real difference is that the California legislation seeks to make these rules law instead of the useless, voluntary guidelines given at the federal level.

But ultimately, both the state and FDA plans share the same critical problem — they leave a loophole for supposed disease prevention.

Just like under the FDA guidance, farmers in California would simply be compelled to change the reason for using antibiotics without actually reducing the amount they feed to their animals. And since many of the antibiotics approved for growth-promotion are also approved for disease prevention, this is effectively just a matter of checking off a different box.

The livestock and drug industries contend that the drugs are needed to prevent outbreaks of disease. But the continuous low-dose use of the same antibiotics has been proven to not only be ineffective in preventing disease but actually gives rise to drug-resistant superbugs.

Gov. Brown agreed with advocates, including our colleagues at Consumers Union, who argued that this bill should be vetoed with the hopes of ultimately resulting in a piece of legislation that could reduce the amount of antibiotics being used without any therapeutic purpose.

“Scientists around the world are warning that we are over-using these life-saving medicines in both human medicine and to raise animals,” wrote Gov. Brown in his veto message [PDF]. “I am directing the Department of Food and Agriculture to work with the Legislature to find new and effective ways to reduce the unnecessary antibiotics used for livestock and poultry.”

The veto was applauded by groups seeking stronger regulation on antibiotics.

“The overuse of antibiotics in food production is making antibiotics ineffective for treatment of human disease. Antibiotics should be used on the farm only for the treatment of sick animals, for a limited period of time, as antibiotics are used in human disease treatment,” said Elisa Odabashian of Consumers Union. “We congratulate Governor Brown for his unwillingness to codify weak FDA guidance that allows antibiotics to continue to be overused on healthy farm animals for disease prevention instead of disease treatment.”

“In vetoing this bill, the Governor has called for stronger action to curb unnecessary antibiotic use in California,” said Jonathan Kaplan of the Natural Resources Defense Council. “We face a rapidly accelerating public health crisis due to antibiotic resistance. Clearly, the Governor is not going to accept good intentions and fig leaf solutions to tackle this problem. Instead, we need to lift the curtain of secrecy that now shrouds the industry’s abuse of these drugs and eliminate unnecessary antibiotic use so that these precious medicines keep working for people who need them.”

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