The U.S. Food and Drug Administration (FDA) released today the first-ever government tally of the quantities of antimicrobial drugs sold domestically for use in food animals. The total — 28.7 million pounds for calendar year 2009 — affirmed earlier estimates by advocacy groups.

The agency did not, however, report the data in a way that makes it possible to distinguish the quantities of drugs used to treat sick animals from those used to promote growth or prevent disease — a key factual dispute between the public health community and organizations representing meat production, pharmaceuticals and food-animal medicine, including the American Veterinary Medical Association (AVMA).

In a statement on its website, the FDA said breaking out the data in that way would have disclosed confidential business information. The agency declined to comment further.

The AVMA, the nation's largest veterinary organization with roughly 80,000 members, does not plan to publicly respond to the report, spokesman David Kirkpatrick said.

Thursday’s figures are the first released under a data-reporting provision passed by Congress in 2008. The new requirement was meant to inform the national debate about the proper use of antimicrobial drugs in food animals, and its link to drug-resistant infections in humans.

Many in the public health community believe that the practice of giving low doses of antibiotics to cattle, pigs and poultry that are not clinically sick promotes the development of antibiotic-resistant bacteria and could be phased out without significant consequences. The meat and poultry industry, drug makers and the AVMA oppose curtailing such uses, maintaining that doing so would compromise animal health and food safety while delivering little or no benefit in the fight against drug-resistant infections in humans.

For years, two competing estimates of food-animal drug use have been commonly cited: a 2001 report from the Union of Concerned Scientists, an environmental advocacy group; and figures released by the Animal Health Institute (AHI), which represents the interests of pharmaceutical giants. The Union of Concerned Scientists used publicly available information about antimicrobial treatment practices to estimate total use in food animals at 29.6 million pounds, with nearly all that amount — 27.6 million pounds — administered for growth promotion and disease prevention. The AHI’s most recent data, drawn from surveys of its drug-making members, indicated that total food-animal antimicrobial use in 2007 was 27.8 million pounds, including 3.6 million pounds used for growth promotion. The AHI did not report a figure for quantities used for disease prevention.

An AHI spokesman said the group likely would release a statement on the FDA's findings. The Union of Concerned Scientists did not immediately respond to a request for comment.

The federal government does not report official estimates on the quantities of antimicrobial drugs used by humans. The 2001 Union of Concerned Scientists report used outpatient and hospital prescribing data to estimate annual human use at 3 million pounds.

Legislation to restrict the use of drugs for growth promotion and disease prevention in food animals has been introduced in Congress several times but has never advanced beyond committee.