piggie thx to nick saltmarsh on flickr creative commons

Ever since the FDA announced plans nearly two years ago to strengthen oversight of antibiotic use in food-producing livestock, critics have complained that a gaping loophole exists that could undermine the program. California, however, may adopt a first-in-the-nation law designed to plug that gap in the next few days. A bill may be signed by California Gov. Jerry Brown by Sunday.

The effort comes amid increasing concern over antibiotic resistance among humans, which has been blamed for at least 2 million illnesses and 23,000 deaths in the United States, according to federal health officials. Importantly, about 70% of antibiotics used to treat Americans are also used in food-producing livestock, according to the Natural Resources Defense Council, an advocacy group.

So the FDA plan calls for drug makers to voluntarily curtail antibiotic use for growth promotion by 2016. They are also supposed to remove language from labeling that indicates antibiotics can be used for weight gain, which makes livestock better suited for increased food production. An industry trade group has maintained the companies will comply.

But here’s the rub: many antibiotics that are approved for bulking up are also approved for preventing disease in animals. Approximately 60 of nearly 300 different medicines that are to be regulated as part of the FDA plan have product labeling that would allow for such use, according to the Pew Charitable Trusts.

The California bill contains language to mitigate the possibility antibiotics could also be used to fatten livestock under the guise of thwarting an illness, according to Avinash Kar, a senior attorney at the NRDC. “The problem is that the FDA does not put any limit on prophylactic use,” he told us. “This would prevent regular use of the drugs for growth promotion. It goes a long way toward closing that loophole.”

The bill also requires the California Department of Food and Agriculture to collect on-the-ground data on how antibiotics are used in livestock. “There aren’t many specifics,” Kar said, “but having a monitoring program for usage is important.”

By contrast, the FDA has only proposed reporting requirements on the amount of antibiotics that are sold for use in different types of food-producing livestock. By collecting such data, the FDA contends it can better track antibiotic use by farms that raise hogs, cattle, chickens, or turkeys for human consumption.

The bill, by the way, also calls for greater oversight of veterinarians, who may suggest antibiotics but fear losing farming clients if they recommend less usage.

What do drug makers think about the bill? We asked the Animal Health Institute for comment, but have not received a reply from the trade group. We will update you accordingly.

Whether other states will adopt similar legislation is uncertain. But Kar believes that any move by California may set the tone for others to follow, given that agriculture is a large component of the state economy. Based on cash receipts, California is the largest agricultural producer, according to the US Department of Agriculture in 2013, and livestock was the fourth-largest commodity.