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Where’s the beef on farm antibiotics?
By Steven Milloy “The ticking time bomb” is what the Union of Concerned Scientists calls the use of antibiotics on farm animals. UCS’ new report, “Hogging It: Estimates of Antimicrobial Abuse in Livestock” claims antibiotic use in farm animals has been drastically underestimated and, worse, “evidence... mounts indicating the human health consequences...” UCS paints a picture of infectious diseases such as typhoid, whooping cough and scarlet fever being just around the corner unless farm animal antibiotic use is curbed. Farm animals are administered antibiotics usually to treat and prevent disease (therapeutic), and sometimes to promote growth (subtherapeutic). Most of these antibiotics have no application to human medicine. Controversy exists about whether such uses will cause drug-resistant bacteria that may one day pose a public health problem. The controversy aside, though, “Hogging It” is more aptly named “Dogging It.” The UCS has set fear way ahead of the facts. The UCS claims industry underestimates the use of antibiotics in farm animals by 40 percent (24.6 million pounds versus 17.8 million pounds). The industry estimate is based on sales of ingredients, according to the Animal Health Institute. The UCS claim, in contrast, is extrapolated from herd size numbers and approved drug dosages. It’s facts versus alarmist guesswork. More problematic is the “mounting evidence” of human health consequences claimed by the UCS, which spotlighted -- and misrepresented -- two recent studies published in the New England Journal of Medicine. A May 1999 study reported a foodborne outbreak of salmonella poisoning that made 27 people ill and caused two deaths in Denmark. The bacteria were resistant to fluoroquinolones, a class of antibiotics. Danish investigators were able to trace back the outbreak to a slaughterhouse, where a herd of swine were infected with the same antibiotic-resistant strain of bacteria. “Hogging It” quotes the president-elect of the American Society for Microbiology describing the study as “the closet that anyone has come to a smoking gun” linking farm use of antibiotics to antibiotic resistance. But contrary to the UCS’ implication, the study’s researchers admit it’s impossible to determine how the swine became infected with resistant salmonella. They don’t know whether the bacteria were introduced by pigs outside of Denmark, wild animals or equipment. Flurorquinolones weren’t used in those herds that year. Prior use of fluoroquinolones couldn’t be blamed either. Smoking gun? Someone’s certainly been smoking something. An April 2000 study doesn’t fare any better. That study reported “evidence that antibiotic resistant strains of salmonella in the U.S. evolve primarily in livestock.” It involved a 12yearold Nebraska farm boy who suffered salmonella poisoning. The salmonella strain identified was resistant to ceftriaxone, the antibiotic of choice for invasive salmonella disease. Cattle from boy’s farm and three other local herds were tested for salmonella. The boy’s salmonella strain reportedly matched the strain of salmonella from one of the tested herds. The researchers concluded the boy’s infection was acquired from one of the herds. But the study has gaping holes preventing that conclusion from being reached. The researchers couldn’t determine how the boy became infected with salmonella. There was no evidence he consumed contaminated meat or came into contact with contaminated animal feces. Although the salmonella strain isolated from the boy matched a strain in one herd, the match apparently wasn’t from the family’s herd. The researchers reported the boy did not accompany his father on visits to the other herds during the twoweek period before his illness. So how the boy became infected with salmonella is a mystery. The researchers could not rule out “unknown environmental factors” as the source of the resistant salmonella. Cattle can acquire salmonella from birds or other wildlife. There wasn’t even any evidence the cattle were treated with ceftriaxone, the antibiotic in question, or any other antibiotics. It’s jumping-to-conclusions that’s mounting; not evidence. Bacterial resistance to antibiotics is on the rise. The bacteria streptococcus pneumoniae, the cause of most acute ear infections in U.S. children, was susceptible to all penicillins and cephalosporins until 1974. By 1996, 21 percent and 9.3 percent of pneumococci resisted those drugs. So far, the only cause that everyone agrees about is that physicians hand out antibiotics like candy. A study in the Journal of the American Medical Association recently reported that doctors wrote in a single year 12 million antibiotic prescriptions for colds, bronchitis and other respiratory infections. But the study noted more than 90 percent of such infections are caused by viruses impervious to antibiotics. Another recent study concluded as many as half of all antibiotic prescriptions are not needed. Development of bacterial resistance isn’t unexpected and, most importantly, isn’t a crisis. We’re lucky resistance is developing so slowly. Researchers have plenty of time to develop new antibiotics. It’s a problem that needs attention. Government and industry research is ongoing. Hysteria is unwarranted. Why the UCS attack on farm use of antibiotics? The crusade is part of its anti-technology, anti-business agenda. UCS advocates “sustainable” or “holistic” agriculture — euphemisms for agriculture without labor-saving machinery, biotechnology, fertilizers and pesticides. Ever the extremists, the UCS even claims the energy used to refrigerate and transport the products of so-called “industrial agriculture” contributes to alleged global warming. It is certainly legitimate to have a constructive dialogue about farm use of antibiotics to promote their proper use. If some physicians overuse antibiotics, some farmers may, too. “Hogging It’ is not constructive though. It’s an inflammatory report simply designed to terrorize the uninformed. Steven Milloy is a biostatistician, lawyer, adjunct scholar at the Cato Institute and publisher of JunkScience.com. |