By Sabrina Tavernise

New York Times News Service

WASHINGTON — The Food and Drug Administration said Wednesday that it was beginning to phase out the use of some antibiotics in animals raised for meat, a major policy shift that could have far-reaching implications for industrial farming and human health.

The change, which will take effect over the next three years, is the first serious attempt by the federal government to curb the broad use of antibiotics in farm animals in decades. Pressure for action has mounted as the effectiveness of drugs important for human health has declined, and deaths from bugs resistant to antibiotics have soared. Food producers said they will abide by the rules, but some public health advocates voiced concerns that loopholes could render the policy toothless.

“This is the first significant step in dealing with this important public health concern in 20 years,” said David Kessler, a former FDA commissioner who has been critical of the agency’s track record on antibiotics. “No one should underestimate how big a lift this has been in changing widespread and long-entrenched industry practices.”

Antibiotics, one of the wonder drugs of the 20th century, were initially used indiscriminately in people and animals, experts say. By the 1970s, public health officials had become worried that overuse was leading to the development of infections resistant to treatment in humans. But for years, modest efforts by federal officials were thwarted by the powerful food industry and its lobbying power in Congress. The issue of antibiotic overuse in animals and drug resistance has since become one of the leading public health concerns worldwide with at least 2 million Americans falling sick every year and about 23,000 dying from antibiotic-resistant infections.

The agency has changed the rules so that food animal producers would no longer be able to use antibiotics to make animals grow faster. It will accomplish that by asking manufacturers of the drugs to change the labels in a way that would make it illegal for farmers to use the medicines for growth promotion.

The changes, which were originally proposed in 2012, are voluntary for drug companies. But FDA officials said they believed the companies would comply, based on discussions during the public comment period. The two drugmakers that represent a majority of such drug products have already stated their intent to participate, FDA officials said Wednesday. Companies will have three months to tell the agency whether they will change the labels, and three years to carry out the new rules.

Additionally, the agency is requiring that licensed veterinarians supervise the use of antibiotics, effectively requiring farmers and ranchers to obtain prescriptions in order to be able to use the drugs for their animals.