We all know (or should know) that factory meat farming is violent and environmentally destructive. You don't have to be a vegan activist to be disturbed by the conditions in which most meat animals live and die. And you probably already know that a large percentage of pesticide use, water pollution, and groundwater depletion is caused by the intensive cultivation of grain used to feed livestock, especially cattle. The environmental damage caused by the cattle themselves--the enormous expanses of land required, the destruction of native vegetation, the problem of what to do with all that poop--has fundamentally altered entire ecosystems. So that every supermarket can be packed with cheap beef and milk, every town can have scores of fast-food chain restaurants, and most Americans can comfortably participate in the fallacy that a meal is not a meal unless it contains meat, we feed, pump full of drugs, and confine about 96 million cattle every year. We kill about 30 million.

We would all be better off without so much meat. Still, the cattle industry has proved as resilient as most Americans are oblivious to the process by which that burger came to their table. Despite a decade's worth of bad news about beef, the average American still eats 66 pounds [in 1999], and beef consumption typically goes way, way up in the summer months. How many hamburgers have you had since Memorial Day?

A new player, however, has emerged in this game and could force the issue and destroy the multibillion-dollar beef industry: the infective prion, the agent that causes mad cow and similar diseases. Unfortunately, prions also have the potential to cause human suffering on an enormous scale. The recent discovery of mad cow disease in Canada and a good look at the ineffectual efforts to avoid it here show that the disease is not far away from us at all.

Meat Market Prions

Until the 20th century, most people who ate meat either grew or hunted it themselves; the animals you ate lived where you did and ate what they had evolved to eat. Now, though, we have the factory meat industry, to which it is difÞcult to offer any compliments. From the near-extermination of American buffalo to the return of the low-paying, dangerous slaughterhouse job to the present treatment of living creatures as commercial products packed in tight boxes and fed everything from cardboard to chicken shit, its unsavory history goes back more than 100 years.

But the meat industry may yet be undone--not by squads of vegetarian activists, but by itself. All evidence suggests that the power of the infective prion has been fortiÞed and widely spread in the past 30 years by the practices of the factory meat farm. No simple cousins of the E. coli bacteria, prions apparently have their own biological category, are undetectable by ordinary tests, and resist all normal methods of disinfection. They cause fatal degenerative brain diseases that have no treatment and no cure, cross species barriers, and have killed more than 130 people in the U.K. who ate infected beef, and there is a possibility that many more will die. If anything is going to bring down factory meat farming, the prion is it.

Unfortunately, if this happens, it may also bring down anyone who's been exposed to meat or animal-derived products in the last 30 or 40 years--that is, for all practical purposes, everyone. Vegetarians and vegans are not immune; prions may exist in the bovine materials used in common vaccines. Did you chew on Altoids mints in the 1980s? They used to be made with beef gelatin. Had surgery? Prions survive standard medical autoclaving disinfection procedures, and prion disease has been spread from human to human via contaminated equipment. If a slaughterhouse processes one cow infected with mad cow disease, the meat of those that follow may become infected too, making even organic beef suspect. And many cosmetics and other pharmaceuticals contain bovine products.

There is some good news in prion research: It seems that tetracycline antibiotics may slow the incubation period, so that it might, say, take you 15 years to develop symptoms rather than 10. Of course, since there is currently no way to diagnose prion disease until symptoms appear, this may be less useful than it sounds. There's also evidence that part of the population may be genetically resistant.

Still, it does seem that anyone who's devoted enough time to the subject is deÞnitely not casual about the possibilities, especially when the woefully inadequate United States Department of Agriculture (USDA) and Food and Drug Administration (FDA) efforts to prevent American mad cow disease are considered. Canada's rules were similar to ours. The only reason mad cow hasn't been found here yet, I believe, is that we are not looking for it.

What is a prion anyway? The word "prion" (pronounced "pree-on") was coined by Nobel Prize-winner Stanley Prusiner for the agent that causes transmissible spongiform encephalopathies, also known as TSEs (be ready for many more acronyms). A combination of the words "infective" and "protein," "prion" is a word that Prusiner apparently made up partly for its media-friendly sound. Probably the most famous TSE is bovine spongiform encephalopathy (BSE), or mad cow disease, which showed up in England in 1986. A close second might be kuru, also known as the cannibalism disease. There is also a naturally occurring prion disease in humans called Creutzfeldt-Jakob disease (CJD), which researchers say spontaneously arises in one in a million people; animal versions apparently appear at the same rate. However, like much of the research done with TSEs, this rate is basically an educated guess. (Creepily enough, while I was researching this story, the father of a friend died of CJD in California.) When BSE spread to people in England during the 1980s and 1990s from eating infected beef, the human version was called Variant Creutzfeldt-Jakob disease, or vCJD. It differs from regular CJD in a number of ways, but perhaps the most significant is that it strikes the young; British teenagers have died of vCJD, whereas regular CJD is a rare disease of the elderly. However, there is evidence that some cases of Alzheimer's disease are actually incidents of misdiagnosed CJD.

Prions are highly unusual disease agents, and researchers admit that we don't know much about them. We do know that prions are most densely concentrated in the brain and central nervous system, but they are also found in muscle tissue; depending on the species, prion disease can be spread through eating infected tissue (as in cows) or by casual contact (as in deer). But an infective prion is not an organism; it has no DNA. Yet, somehow, it still manages to infect a host and reproduce itself, which places it outside most known biology; as one researcher put it, prions "differ from all known microorganisms and viruses." The most widely accepted theory is that infective prions are mutated versions of the normal proteins found mostly in the brain. The mutant prions--which seem to have the same chemical formula but a different structure than nonmutant proteins--somehow join the normal ones and cause them to fold themselves into the mutant structure. This then spreads throughout the brain and causes spongiform encephalopathy; the brain becomes a mass of spongy holes. Loss of motor control and dementia set in, and in humans, the patient dies in about six months to a year. An infected host shows no immune response; there currently is no way to definitively test human beings and most animals for prions until the subject is dead and a brain biopsy is performed.

Though prions may have always existed, it is clear that human activity has fortified and multiplied them in ways that would not have happened without the factory farm. Rendering, "turning animal wastes into marketable products," as John Stauber and Sheldon Rampton put it in their book Mad Cow U.S.A., was the crucial element in the dissemination of the BSE prion. The rather disturbing but extremely common practice of feeding cattle, as a protein supplement, meat and bone meal (MBM) made up of rendered animal bodies (including the meat and bones of cows--only about half of a cow can be used for food) went on in England and the United States for decades. In the U.S., a modified version of the practice, which is held directly responsible for the spread of BSE in Britain, still exists on a wide scale.

In England, after the first case of BSE was reported in 1986, more than 180,000 English cows contracted the disease--far more than official projections. British researchers discovered that a cow had to eat only one gram of infected cow tissue--a piece the size of a peppercorn--to be infected. If it is rendered and made into feed, one infected cow can infect thousands of others.

Rendering has a long history--think soap made from beef tallow--but 20th-century industrial agriculture took the process to a whole new level. Animal bodies are dumped into huge vats and cooked down to create, as one byproduct, MBM; it looks like cornmeal. This includes not only millions of leftover farm animal parts but also road kill and the remains of hundreds of thousands of cats and dogs euthanized by animal shelters. So in the United States, dogs are eating dogs, pigs are eating pigs, and until very recently, cows were eating cows. According to Stauber and Rampton, four billion pounds of rendered animal goes into animal feed every year. If you have eaten nonorganic beef in the past 30 years, you have eaten the meat of cannibal cows.

Why are cattle fed this stuff anyway? For one, something has to be done with the remains of millions of cattle slaughtered here every year. For another, cows fed protein supplements produce more milk and grow to a larger size in a much shorter period of time, and MBM protein is cheaper than soy. Dairy cows, most of which are now pumped up on productivity-enhancing drugs, must be fed high-protein supplements. Giving a cow bovine growth hormone, or BGH, requires that you also give it MBM; retired dairy cows become hamburger themselves, and, making a neat circle, their unused body parts are rendered into MBM again.

In 1997, years after it was clear what was causing the spread of BSE in Britain, the FDA finally banned the feeding of protein supplements derived from cows to cattle in the United States. Canada's feed ban took effect the same year. Nevertheless, cattle-derived feed is still widely available; according to FDA regulations it must only be clearly labeled with the warning "not to be fed to ruminant animals," like cows, sheep, and deer, and feed mills must store it separately. Whether or not farmers follow these directions is up to them. Also, pigs, dogs, and cats can still be fed cattle MBM, and when these animals die, they can be fed to cows. This is why recent research on the way prions can cross the species barrier--and the fact that animals infected with a TSE do not necessarily show symptoms--is so disturbing. Even more disturbing is the fact that the body of the Canadian mad cow, which was not originally suspected of having BSE, was rendered, joined with the bodies of thousands of others and made into animal food shipped to the U.S. and elsewhere.

Last summer at a national conference for wildlife professionals in Denver focusing on the deer and elk TSE known as chronic wasting disease (CWD), Rick Race, a researcher with the National Institutes of Health, asked a very important question: "What's happening in animals that don't get sick?" His team injected mouse brains with a large dose of a hamster TSE. After a few years, a few of the mice got sick and died of prion disease, but most did not. Then the "healthy" mice were killed and their brain tissue was injected into new mice. The entire second group of mice contracted a fatal TSE. A new strain of the hamster prion disease had been created, one that was particularly deadly to mice. Race's research shows that even though the infective prion can exist in a host without causing disease, this does not diminish its infectivity should that host's nonsymptomatic body become a means of transmitting the agent.

So if an apparently healthy animal is killed, rendered, and fed to other animals, not only might the apparently healthy animal be carrying a TSE, but the TSE may then cross the species barrier to infect and sicken a new animal. Granted, these experiments used intracerebral inoculation to transmit the infective prions, a method far more effective in transmitting TSEs than eating infected tissue or having contact with it. Still, they demonstrate something very disturbing, something to which government officials and meat-industry executives in this country have been extremely slow to respond.

BSE in the USA
In November 2001, the Harvard Center for Risk Analysis (HCRA) published a report analyzing the risk of BSE occurring in the United States. The group reached the conclusion that "there is little chance that the disease will be a serious threat either to the American cattle herd or to public health." Why? Because even if BSE were introduced into the American cattle population, "in all cases, the disease fails to take hold and dies out, usually within a matter of a few years." According to the press release, HCRA's computer modeling showed that even in the worst-case scenarios, the number of sick animals would remain small, and the amount of contaminated meat entering the human food supply and causing vCJD would be "minute."

It is very important, however, to understand the essential condition for Harvard's conclusion to be truly reassuring. That condition is the enforcement of the 1997 FDA ban on feeding cattle-derived meat and bone meal to cattle.

Despite the feed ban, compliance and enforcement among renderers and feed mills have been less than rigorous. When the GAO, the Congressional General Accounting Office, looked into the matter for a report issued last year, it found that the FDA's enforcement of the feed ban was limited, and the inspection data was "significantly" flawed. Their report noted that there are no penalties for violating the feed ban and that the FDA has no enforcement strategy for feed-ban compliance.

The FDA's database is also filled with serious problems; for instance, entries for about 45 percent of all inspections lack the information that would connect them with an individual feed mill or renderer--crucial if a BSE case were to be traced--and 438 entries did not mention whether prohibited proteins were included in cattle feed, the point of the whole ban in the first place. The GAO wrote, "Even if the FDA were to actively enforce the feed ban, its inspection database is so severely flawed that--until corrected--it should not be used to assess compliance." Last summer the FDA website's most recent "update" on the BSE situation was dated June 2001, and it revealed that 22 percent of all feed mills and renderers inspected that handled the forbidden proteins were in violation of the feed ban.

Then there is the predictable (and, in my opinion, irresponsible) response of the Cattlemen's Beef Association, the marketing arm of the cattle industry. Their official media statement on the Canadian situation lists six reasons why BSE is not a problem here, all of which I consider misleading and manipulative. For instance: "BSE affects older cattle.... The vast majority of cattle going to market in the U.S. are less than 24 months old." "The surveillance system targets all cattle with any signs of neurological disorder." "The U.S. banned imports of cattle and bovine products from countries with BSE beginning in 1989." "The BSE agent is not found in meat. It is found in central nervous system tissue such as brain and spinal cord."

Okay. The reason BSE "affects older cattle" is that usually only older cattle live long enough to show visible signs of BSE. A cow younger than 24 months could easily be infected, and therefore be infective, without showing symptoms. If our surveillance system targets only cattle with obvious signs of disease, we are still potentially missing many animals with BSE. And banning imports does nothing about our domestic situation.

And let's take a long look at that last misleading statement "The BSE agent is not found in meat. It is found in central nervous system tissue such as brain and spinal cord." True, prions are found in the highest concentrations in central nervous system tissue rather than in muscle. But cattle spinal cord and brain tissue are still allowed to enter our food supply, usually in processed meat like hot dogs. Beef stock and beef flavoring are made by boiling skeletons, including the spinal column. The USDA has opted not to tell consumers if the meat products they are buying might contain these tissues, because "labeling and warning statements should be reserved for known hazards, which BSE is not in the United States." Meat processing plants also still use mechanical "advanced meat recovery systems" designed to get the very last bits of meat off a carcass, including the head; this goes into hamburger and processed meats. And the bolt-gun method used to kill meat cattle has been shown to splatter brains all over the rest of the carcass. In any case, recent research shows more clearly than ever that prions are found in muscle tissues--in meat.

The Cattlemen also mention the Harvard study, the one that argued the risk of BSE in the United States was low provided the feeding-cows-to-cows ban was being enforced. The three-year, $500,000 Harvard study was funded by the USDA, it should be pointed out, which is quite friendly with the American cattle industry; many upper-level USDA officials were formerly executives in the meat business and vice versa. George Gray, director of the Harvard study, says the study was peer reviewed and that new regulations have been proposed for industry because of it. "Our task was to characterize the state of U.S. BSE risk management. Testing of cattle does nothing to increase protection against the disease." This is arguable--in the U.K., BSE has been nearly eliminated, largely due to intensive testing of even healthy-looking cattle, as well as enforcement of a much more severe feed ban. The rules are similar in Europe. In the Old World, cows no longer eat meat. (To be fair, the USDA and the FDA--most likely in response to the GAO report, not the Harvard report--have started to take action. Never fear: Advance notices of proposed rulemaking on the people-eating-cattle-brains problem are scheduled to begin soon!)

There are additional problems with the Harvard study: It looked only at the effects of introducing between one and 500 BSE-infected cattle into the country. But we have imported millions of cattle from Canada, and as author John Stauber told me, we don't know if there is one mad cow there or a thousand. We also import cattle from Mexico, where our feed-ban labels are written in English. The Harvard study also focused on the possibility of BSE being introduced into the United States, not on the possibility that it might already be here unreported. But given the long incubation period for TSEs, as well as the fact that testing actual American cows for the disease did not start until 1990, it is quite possible that we have our own strain of BSE. Though bans on British beef and cattle went into effect almost immediately when BSE was first found in the U.K., we lived in the identical meat-processing situation as the Brits for decades, on a much wider scale. Stauber says the Harvard study is "garbage."

Is it possible that the USDA is deliberately not testing as much as it should? The USDA performs important marketing work for the multibillion-dollar American beef industry. If even one case of BSE were made public, it would likely be decimated, much as the English industry was and as the Canadian probably will be.

Finally, the USDA tells us that our BSE testing "vastly exceeds international standards." This statement is pure bunk. Between 1994 and 2001, the USDA tested only 4,870 cattle brains for BSE--.0005 percent of our 96 million cows. The USDA now announces that it has "tripled" the number of BSE tests, to 20,000 in the past year. But between 2001 and 2003, England--a country dwarfed by our western cattle-raising states--tested more than 500,000 cows. In Japan, where BSE was found a few years ago, all cattle are tested. Stanley Prusiner says that U.S. testing standards are "appalling." I believe it is safer to eat beef in the U.K. than it is here.

Chronic Wasting Disease
Since I believe prions are a new kind of environmental pollutant created, disseminated, and denied by industry, much like PCBs or pesticides, it makes sense to look at our native wildlife TSE, chronic wasting disease, a prion disease affecting deer and elk all over the country. CWD, formerly endemic to a section of Colorado and Wyoming for 35 years, has advanced throughout the Rocky Mountain and plains states as well as Canada, and recently jumped 900 miles to Wisconsin. The disease has yet to be found in Washington State, but Washington has 300,000 deer and is much closer to Wyoming and Colorado than Wisconsin is.

All signs point to CWD originating in deer and elk farming. In many states, wild animals are raised in captivity to provide the clients of the "canned hunting" industry with the privilege of shooting a large, hand-fed bull elk (at $20,000 a pop), or to grow exotic products like antler velvet, used in Asian herbal medicines. And nothing seems to be prohibiting deer farmers from feeding their deer whatever they please, including MBM feed. Another problem is the practice of feeding or baiting deer, either for hunting or for recreational purposes. Since CWD (unlike BSE) is spread by casual contact, the overpopulation of white-tailed deer almost everywhere augments the problem.

Deer overpopulation is, of course, as American as apple pie. Government and industry efforts in the first part of the 20th century to eradicate "varmints"--any perceived predator of cattle or sheep--also created a world in which deer could multiply like rabbits. The transformation of forests into farms and suburbs also vastly increased ideal deer habitat. And too much of any animal causes the environment to change. For example, to feed themselves, deer now routinely mow down all kinds of tree seedlings, resulting in fundamental alteration of forest botany.

Most wildlife biologists agree that CWD was released into the wild in 1967, when it appeared at a Colorado research station. The disease was not then known to be as serious as it is, and experimental animals were set free. However, even after being recognized as a TSE in the late 1970s, CWD did not seem to be having a major effect on the deer and elk population, and nothing much was done about it. Now, though, in the endemic area of Colorado and Wyoming, up to 15 percent of the deer and elk are infected. Until two years ago, CWD was unknown in Wisconsin. It is thought to have been introduced to the state when an infected Colorado game-farm animal was imported.

Deer hunting is a family tradition there, and almost a million Wisconsin hunters used to kill more than 300,000 deer every season--something that still did little to alter a population estimated at more than 100 deer per square mile. Now, though, an "eradication" effort is in place to remove as many deer as possible from the hot zone in southwestern Wisconsin. Projections show that if nothing is done about CWD, within 20 years Wisconsin's white-tailed deer population will crash.

But though hunting seasons were extended and bag limits removed, last season, the hunter turnout was less than impressive. There are different kinds of hunters, and many feel hunting is an ethical pursuit, bringing man closer to nature. When deer hunting became deer killing, this illusion was lost.

Even though about a dozen young hunters from CWD areas have died of CJD, wildlife officials have taken pains to reassure us that there is no evidence that CWD can be transmitted to humans by eating venison. Still, hunters are being told not to consume meat from obviously diseased animals; of course, the problem with prion diseases is that an animal can be infected but show no symptoms. (Remember those "healthy" mice?) This means that just as with cows, simply looking at deer to see if they are sick is not adequate to detect TSEs--their brains must be removed and tested. The current Wisconsin infection rate is about 3 percent. Studies are currently being organized to see whether scavenger animals can also catch the disease.

So, along with spreading prions among wild animal populations, CWD also potentially creates another environmental problem. Whether by disease or fear of disease, if deer hunting is destroyed, state wildlife management agencies will lose millions of dollars in fees and licenses. Nationally, hunting fees contribute about $1.3 billion every year to fund wildlife resource management; this benefits more than just particular game species. However you feel about hunting, sportsmen passed laws to protect wild animals decades before many people had even dreamed of such a thing, and they continue to contribute significantly to the well-being of wildlife habitat.

What about the cows? So far it seems that CWD does not transmit to cattle, at least not through casual contact. However, plenty of deer since 1967 have been hit by cars, rendered, and made into cow food.

The mood at the chronic wasting disease conference in Denver was quite sober. Since sportsmen and wildlife workers tend to be pretty good-natured, the atmosphere lifted during breaks, but it was clear that among the room of hearty-looking men and tomboyish women the issue was of grave concern. When one researcher presented his findings that the CWD prion was, in fact, weakly transmissible to human cells in the test tube, at about the same rate as BSE, I could feel the burden that had just fallen on the shoulders of all those listening. More than 400 were present, but the room was very quiet.

Conservatives and corporate interests have put a lot of energy into creating the impression that wanting something other than the status quo--a status quo that is increasingly dangerous to public health--is akin to being communist. But it is absurd to think that wanting food free of fatal disease agents, from animals that did not spend their lives being tortured, makes you into some kind of hippie freak. It's partly our own fault for being ignorant and complacent; we have spent a long time accustomed to cheap food, too long uncurious about where it comes from and indifferent to the suffering our habits have created for other creatures. Should a BSE disaster come to pass, I can't help but consider that we are simply reaping what we have sown. Our environmental problems may come to include the effects of biological agents not previously known--or, in the case of genetic engineering, not previously in existence. Imagine creatures akin to PCBs that can fly or swim, or dioxin that can reproduce itself.

This is science-fiction doom mongering, of course, but there are still many questions worth answering. The primary one should be: Why do we not follow the precautionary principle in this country? That is, why are we repeatedly told by industry and politicians that harm must be unequivocally and "scientifically" proven--a process that can be drawn out almost indefinitely--before any action regulating industry can be taken?

At the Denver conference, organizers almost begged the media not to write hysterical the-end-is-near articles about CWD or about prion disease. They also, however, ended the two-day event with serious requests that everything known about them be told, including the possible risks, both to benefit the public and to avoid the PR nightmare that happened in England after years of government denials. (Obviously the prime minister of Canada, who went on TV to eat a big steak in a scene reminiscent of that in England when John Major fed a hamburger to his daughter on camera, learned nothing from the English experience. The leaders of BSE-infected countries eating beef in front of TV cameras has already become a cliché.)

Nothing much seems to have happened yet, and nothing much may happen; still, when some of the most prominent people in the field believe there is a real possibility for very negative consequences, it is hard to ignore them. I asked Harriet Ritvo, an environmental historian at MIT, if she thought the media was being hysterical about mad cow disease.

"I don't think the media is being hysterical enough," she said.