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DON’T EAT THE BEEF! The Obama Administration in mid-March boasted of “closing a loophole” that risked public health by allowing animals not obviously ill, but nevertheless unable to walk into the packing plant, to enter the food chain. USDA claimed it will keep animals infected with “mad cow” out of the food chain. (All four to seven of them, that is, theoretically hiding somewhere in the U.S. cattle herd, according to best estimates.)
Just how risky? In the United Kingdom, where mad cow disease did measurably exist in the cattle herd (unlike the U.S.) and where human disease linked to beef occurred, (unlike in the U.S.), the Centers for Disease Control estimates beef eaters there faced a 1 in 10 billion chance of getting the disease — roughly one half of one thousandth of a percent of the likelihood Earth will be hit by an asteroid.
As one anonymous Internet pundit suggested, skipping meat to avoid BSE is sort of like moving to Antarctica to avoid Komodo Dragons.
DON’T DRINK THE WATER! The Associated Press in mid-2008 reported results of its own “investigation” of minute amounts of pharmaceuticals in U.S. drinking water, saying it had discovered traces of not only antibiotics, but also pain killers, anticonvulsants, mood stabilizers and sex hormones. Headlines splashed conclusions that the drinking water of “at least 41 million Americans” was “contaminated,” and that compounds “lurking” in their water were “heightening worries among scientists” about health consequences.
AP failed to add to its exposé that such reports date back nearly four decades now. But, according to Shane Snyder, PhD, Southern Nevada Water Authority, the reports are connected less to increasing contamination then they are to detection technology that’s become so good it’s now “possible to detect and quantify nearly any compound known to humankind at diminishingly minute concentrations in water.”
Dr. Snyder’s recent scientific review of the issue showed that while some pharmaceuticals were indeed measurable in trace quantities in water supplies, none have occurred at levels relevant to human health.Their presence must be contextualized with those levels, he says. Otherwise, if mere presence becomes the litmus test for risk, we chance spending scarce resources and contributing to global warming by overtreating water unnecessarily.
RISKY BUSINESS. Farm antibiotics, too: “Each year we fail to take action on this critical issue increases the risk that drug-resistant bacteria will threaten the health of the American people,” according to Sen. Olympia Snowe, R-Maine, who in March cosponsored yet another round of federal legislation to ban most antibiotic use on farms.
Meanwhile, scientists and product manufacturers have been doing the real heavy lifting behind the issue, conducting the science to determine whether any risk really exists, at what level, and whether the talk of risk amounts to anything of substance.
Scientific Risk or Political Risk?
“The risks to public health are immense.... Congress should... eliminate the use of antibiotics in animal feed.”
Akron Beacon Journal Nov. 26, 2007.
“Congress must act now to [force accelerated reviews of existing antibiotics]. If it fails to do so, it risks passing a bill that compromises America’s public health.”
Baltimore Sun, July 10, 2008
“The nation is clearly at risk of an epidemic outbreak of food poisoning caused by drug-resistant bacteria....”
Sen. Edward Kennedy, Feb. 12, 2007
Clearly some politicians sense there’s risk about antibiotic use in farm animals. But is it scientifi c risk or political risk?
WHAT THE SCIENCE SAYS Consider the case of penicillin, the 50-year-old poster child for the panic surrounding farm antibiotic use — panic as in: “Drugs such as penicillin and tetracycline, used routinely to treat respiratory disease and heart infections in humans, are also fed routinely to farm animals — not to treat diagnosed disease, but to promote growth and to compensate for the overcrowded, stressful, unsanitary conditions on factory farms,” as penned in July’s Baltimore Sun by the activists Margaret Mellon and David Wallinga.
The fact is, according to manufacturer data compiled by the nonprofi t Animal Health Institute, the amount of penicillin sold to U.S. farmers is only a fraction of all such antibiotics, and the portion of that portion used solely to improve performance amounts to a rounding error on the tonnage of human antibiotics prescribed every year. The specifi c form of penicillin approved for anything other than disease prevention and treatment is not used at all in cattle, and USDA survey data show 99.5 percent in swine is given for disease treatment, control or prevention.
IS HUMAN HEALTH AT RISK? Still, it’s theoretically possible farm use of penicillin could impact effectiveness of penicillins in humans. So risk-assessment specialist and theoretical mathematician Tony Cox, PhD, and systems modeling specialist Douglas Popken, PhD, compiled the available numbers on hospital intensive care unit Enteroccocus case loads and their rates of resistance to human penicillin. Then, using a set of better-safe-than-sorry estimates about other factors, they attempted to tease out which portion of deaths can correctly be attributed to an infection that likely came from animals, which was made harder to treat with penicillin because on-farm use of penicillin made it more resistant to the drug.
Drs. Cox and Popken’s calculations predict continuing use of penicillin risks leading to an additional 0.135 deaths per year in the entire U.S. population — or about one additional death every seven to eight years, if current conditions persist. Using less conservative assumptions, the estimated risk falls to about 0.04 excess deaths annually, or about one every quarter century. Assuming the average American lives 80 years, that means he faces an increased risk that’s about 3,600 times lower than the risk normally considered acceptable for cancer-causing compounds in the environment. And since Drs. Cox and Popken modeled the risk for all penicillin uses, the risk attributable solely to low level use in feed is almost certainly even lower.
GETTING BEYOND BLAME Such careful, quantifi able risk assessments are a necessity if we’re going to move from simply blaming to developing management strategies that make a difference, Dr. Cox says. “Scientists who want to affect policy have an obligation to do much more than raise potential threats. They should have an obligation to say something useful about the magnitude of those potential threats,” he says. “Providing only a little information, charged with emotional triggers, but without quantitative risk information that helps clarify basis for effective action, can manipulate people into wasting limited resources in ways that do very little or no good.”
Antibiotic Risk Analysis Research Highlights
HOW EFFECTIVE IS A BAN? Risk assessment expert and author Tony Cox, PhD, used existing data on treatment failures due to Enterococcus faeceum resistant to the antibiotic vancomycin and worked back to use on farms of the related antibiotic virginiamycin. His model then predicted the number of human treatment failures that could have been prevented assuming the antibiotic were banned. The result? 1.8 cases in the entire population over five years following a ban, saving an estimated 0.29 lives.
Cox LA, Popken DA. Quantifying human health risks from virginiamycin used in chickens. Risk Analysis, 2004; 24(1):271–288.
RARE RISKS. Iowa State veterinary epidemiologist Scott Hurd, DVM, PhD, modeled the risk of continuing to use macrolide antibiotics in the U.S. His study shows that even using conservative estimates, the estimated risk of compromised treatment outcomes are vanishingly low:
RISK IN NOT MEDICATING. Other work by Dr. Cox estimates ending the use of virginiamycin in animals would likely cause an additional 6,660 human illnesses per year caused by Campylobacter. Since the number of illnesses avoided by not using the antibiotic would be less than two per year, the model demonstrates that withdrawing animal antibiotics can cause far more human illness-days than it would prevent.
Cox LA Jr. Potential human health benefi ts of antibiotics used in food animals: a case study of virginiamycin. Environ Int. 2005 May;31(4):549-63.
BAN CAUSED DISEASE? Dr. Cox again draws on existing human health data to predict that ending use of the fl uoroquinolone enrofl oxacin (which FDA mandated in 2005) and macrolides in U.S. broiler production would be expected to cause an added 1,000 cases of Campylobacter- related illness for every one case it avoided.
Can We Rely on the Media to Report it Right?
Lawmakers, too, read the media, (both House and Senate bills to ban farm antibiotics, for instance, quote the supermarket checkout magazine Consumer Reports). So it’s worth asking: Do they get it right when it comes to reporting on health risks? Minnesota journalism professor Gary Schwitzer, PhD, reviews health journalism research, surveys health care journalists and interviews journalists for his annual report on the state of health reporting. His conclusion this year: Financial stress in the media has contributed to some “troubling” trends. They include “quick hit” stories, often based on summarized medical studies, which tend to sacrifi ce quality, fewer in-depth or complex stories, especially about health policy, and more lifestyle and consumer healthrelated fluff stories.