Photograph by Jim Richardson
Republished from the pages of National Geographic magazine
The chief topics of discussion one midsummer afternoon in a conference room at the Centers for Disease Control and Prevention (CDC) are ground beef, eggs, salad, almonds, and cilantro. This is no conversation about the lunch menu but a review of outbreaks nationwide of disease caused by food. At the table are 26 epidemiologists—medical detectives charged with investigating the mysterious links between contaminated food and the illness it causes.
The stories are not those I expect to hear, of people getting sick from drinking unpasteurized milk or eating deviled eggs left too long in the hot sun at a picnic, but tales of people sickened by contaminated parsley and scallions, cantaloupes, leaf lettuce, sprouts, orange juice, and almonds; refrigerated potato salad, eggs, chicken, salami, and beans; hot dogs, hamburgers, deli meats. The food culprits were served in kitchens, restaurants, and nursing homes, on cruise ships and farms, at churches and temples, family reunions, county fairs, casinos, day-care centers. They were distributed among many towns, in many states.
According to the CDC, each year in the United States 76 million people suffer from food-borne disease; 325,000 of them are hospitalized and 5,000 die. In the developing world contaminated food and water kill almost two million children a year. The epidemiologists in this room are keenly aware that behind the numbing, cold-potato statistics are real people, particularly the very young and the very old, who have suffered debilitating, even lethal, disease from what most of us consider one of life's less risky activities: eating.
On the face of it, it seems that "risk" should not be in the same sentence with "food"—that essential and wholesome component of life, so mixed and mingled with comfort, security, even love. But often it is. In recent years we've heard about the dangerous adulterants contaminating our food: pesticides on our grapes, carcinogens on our strawberries, chemicals on our apples, poisonous metals in our fish. We've heard dire warnings of the long-term effects of taking in too much fat or salt or cholesterol. In fact, in the past 30 years or so, there have been so many findings about the possible ill effects of our meals—some of them refuted shortly after being announced—that many of us have become inured to the red flags raised over food dangers.
I consider myself knowledgeable about safe eating. I thought I knew how to buy safe foods; how to clean, cook, and eat them properly; which dishes to order in restaurants and which to avoid. But the stories I have heard from food safety experts and the tales swapped among the epidemiologists at the CDC have swept away my assumptions. I'm starting to rethink the way I shop, cook, eat, feed my children, even the way I define food and see its place in the world.
Among the agencies that oversee the safety of the U.S. food supply is the Department of Agriculture (USDA), charged with regulating meat and poultry and foods that contain them. It also regulates pasteurized egg products. The Food and Drug Administration (FDA) addresses the safety of all other foods, including fresh produce, canned and imported foods, milk, shell eggs, seafoods, and any processed foods that do not contain meat and poultry. These agencies post periodic alerts about hazards in food—chemical contaminants, food additives, unlabeled allergenic ingredients. These are matters of serious concern. But most government officials and health experts agree: The greatest hazards today in the American food supply are not pesticide residues or dioxins or even hidden allergens but food-borne pathogens—bacteria, viruses, parasites—with the potential to harm or kill us.
Once, while on assignment for this magazine, I fell ill in an oceanside town in California after a hotel dinner of seafood and salad. That night I broke into a feverish sweat and suffered abdominal cramps and multiple bouts of diarrhea. By morning I was weak and depleted, but my symptoms were gone. If the statistics hold true, most Americans suffer in this way from time to time. We get a bad stomach for a brief spell or a bout of vomiting or diarrhea. These short-term ailments of our alimentary tracts are typically caused by viruses—often foodborne—and can spread from one person to the next by what is known as the fecal-oral route (contact with human waste and unwashed hands). The symptoms are usually mild and are gone in a day or two.
For some, however, experience with tainted food has another ending, no less chilling for its relative rarity.
A week before Christmas 1992 Lauren Beth Rudolph ate a cheeseburger from a Jack in the Box restaurant in California. On Christmas Eve, suffering from severe cramps and bloody diarrhea, Lauren was admitted to the hospital. There she endured three massive heart attacks and fell into a coma before dying on December 28. She was six years old.
The burger Lauren ate was contaminated with the virulent bacterium Escherichia coli 0157:H7. Her death was what epidemiologists refer to as an index case, the first in an outbreak that caused 732 illnesses in five states and killed four children. Every year some 73,000 Americans become ill and 60—most of them children—die from E. coli 0157:H7. The bug is a close cousin of the beneficial E. coli that normally reside in our own digestive systems. But so virulent is this version that it takes no more than a few organisms to cause deadly infection.
"We used to think of foodborne illness as little more than a stomachache," says Joseph Levitt, director of the FDA's Center for Food Safety and Applied Nutrition. "After the Jack in the Box incident we realized this was no issue of stomachaches, but a serious and compelling public health problem.'
There are 200 times as many bacteria in the colon of a single human as there are human beings who have ever lived. Most of these microbes coexist peacefully with our own cells and even assist them, helping with digestion, synthesizing vitamins, shaping the immune system, and fostering general health. Nearly all raw food, too, harbors bacteria. But the microbes that produce foodborne illness are bugs of a different order, capable of causing severe illness and even lasting damage—disorders ranging from temporary paralysis to kidney disease.
Many of these microbes are present in the animals we raise for food. When a food animal containing pathogens is slaughtered, its stomach contents or manure can taint meat during processing. Fruits and vegetables can pick up the pathogens if washed or irrigated with water contaminated with manure or human sewage.
And since a single bacterium, given the right conditions, divides rapidly enough to produce colonies of billions over the course of a day, even only lightly contaminated food can become highly infectious. The microbes can also hide and multiply on sponges, dish towels, cutting boards, sinks, knives, and countertops, where they're easily transferred to food or hands.
A century ago typhoid fever, cholera, botulism, and trichinosis were common. The incidence of these diseases has fallen, at least in the developed world, thanks to improvements in food sanitation and safety—better animal husbandry, refrigeration, the pasteurization of milk, sophisticated canning and food preservation techniques. Consumers are better educated about how to clean and cook meats and produce, and standards put in place by the federal government have largely rid dining tables in the U.S. of food that is spoiled, contaminated with filth, or derived from sick animals.
But other foodborne infections have taken the place of the old ones—among them, a troubling cluster caused by bacteria with unwieldy names: Campylobacter jejuni, Salmonella enteritidis, E. coli O157:H7, Shigella sonnei, Listeria monocytogenes. Some of these are new forms of old microbes; others are the same as they've always been but are popping up in new places. The foods contaminated with this nasty set of pathogens tend to look, smell, and taste normal, and the offending microbes, we are learning, can survive the traditional heating and cooling techniques we once thought did away with them.
Growing up in the 1960s, I remember the first thing I ever tasted that I wanted to taste again was cookie dough, a sweet, melting mix of butter, brown sugar, and raw eggs. I licked the dough bowl frequently over the years with no ill effect. The wisdom used to be that one should avoid only those raw eggs with cracked shells, which might allow pathogens in.
But now food experts agree that even a perfect egg may not be safe. Salmonella enteritidis—bacteria that can cause diarrhea, cramps, fever, and, in those with weakened immune systems, life-threatening infection—can get inside the ovaries of a laying hen and contaminate her eggs before the shells are formed. Beginning in September 2001 the FDA required that all egg cartons carry a safe-handling label stating: "To prevent illness from bacteria: keep eggs refrigerated, cook eggs until yolks are firm, and cook foods containing eggs thoroughly." Soft-boiled eggs, eggs fried sunny-side up, and even softly scrambled eggs are now on the "unsafe" list along with classic versions of many egg-containing recipes touted in the cookbooks of the past few decades: Caesar salad, mousses, hollandaise sauce, French toast, omelettes, eggnog. It's not wise to make mayonnaise or ice cream with eggs at home anymore either.
In my childhood I also ate with impunity the semi-raw hamburgers served at family picnics, undercooked either because of impatient appetites or a fashion for rare meat. It's clear now that E. coli O157:H7 can survive the gentle heating we give our rare hamburgers. The USDA advises cooks at home to heat ground beef until it's no longer pink and reaches a temperature of 160 degrees Fahrenheit. The standard for commercial food services, where equipment is more reliable, is 155 degrees Fahrenheit.
Other potential troublemakers include patés, hot dogs, sliced deli meats, smoked fish, blue cheese, or soft cheeses such as Brie and Camembert because of the dangers of Listeria. This organism multiplies at refrigerator temperatures. In one study the microbe turned up on the inside surfaces of the refrigerators of two-thirds of the patients infected with Listeria. It doesn't always get into our food, but when it does, it can cause encephalitis or meningitis in people with vulnerable immune systems and, in pregnant women, miscarriage or stillbirth.
Whether the overall incidence of foodborne disease has risen over the past generation is not known because we can't track all foodborne illnesses," says Patricia Griffin, chief of the CDC's Foodborne Diseases Epidemiology Section. "What is clear is that the incidence is high, that some foodborne illnesses have clearly increased, and that dramatic changes in our food production system are likely to be playing a major role."
Until the Jack in the Box outbreak, many consumers believed that people got sick from food they didn't cook right. "Now," Griffin says, "we are more aware that the responsibility does not rest solely with the cook. We know that contamination often occurs early in the production process—at steps on the way from farm or field or fishing ground to market."
Griffin has been in the foodborne-disease business for 15 years. Her job is to look for trends in food-related illness through analysis of outbreaks. Her staff of epidemiologists at the CDC investigates outbreaks by comparing those who have become ill from food with closely matched individuals who are well and by comparing what the two groups ate. In this way they can identify both the food source of an outbreak and the contaminating microbe.
To link cases together, the scientists use a powerful new tool called PulseNet, a network of public health laboratories connected by computer that matches strains of microbes through DNA fingerprinting. PulseNet allows epidemiologists to associate an illness in Nebraska, say, with one in Texas, tying together what might otherwise appear as a sea of sporadic and unrelated cases.
Then it's the job of the investigators to track down the nature and mechanism of the contamination—what changed or went wrong in the food's journey to the table—and to determine whether to recall a particular food or to change the process by which it's produced.
In January 2000 public health officials in Virginia noted an unusual cluster of patients sick with food poisoning from one strain of Salmonella. Using PulseNet, the CDC identified 79 patients in 13 states who suffered infection from the same strain of the microbe. Fifteen had been hospitalized with severe bloody diarrhea; two had died. The common factor? All had eaten mangoes during the previous November and December.
An investigation of the implicated fruit led to a single large mango farm in Brazil. When a team of health officials visited the farm, they discovered that tanks used to dip the mangoes in warm water to control fruit fly infestation, and then in cold water to cool the fruit, were open to the air. There were toads and birds around the tanks and feces in the water. It likely was the cold rinse that caused the mangoes to absorb the tank water and the pathogens it contained, including a strain of Salmonella.
It was a small problem, easily fixed. "That's one reason we investigate outbreaks," explains Griffin, "to find the little things that need to be corrected. These are not generally flukes; they're problems in the way food is produced. They're likely to have happened before and—if they're not fixed—will happen again. Since the mango incident, the farm in Brazil has enclosed its warm-water tanks, and the fruit is air-cooled with fans.
But the mango outbreak had a larger lesson: In the U.S. we no longer eat only fruits and vegetables in season and grown locally, as we once did. Instead, we demand our strawberries, peaches, mangoes, and lettuce year-round. As a result, we are depending more and more on imports. Over 40 percent of all fresh fruit consumed in the U.S. comes from Mexico, Chile, Guatemala, Costa Rica, and other foreign countries, traveling hundreds, even thousands, of miles to reach our grocery-store shelves.
Eating food grown elsewhere in the world means depending on the soil, water, and sanitation conditions in those places and on the way their workers farm, harvest, process, and transport the products. (This is true, as well, for other nations that consume food exported from the U.S. Last spring, almonds from a farm in California infected 160 Canadians with Salmonella.) Because of the globalization of our food supply, the health hazards of one nation easily become those of another.
Not only do we like our foods diverse and available year-round, but we also like them convenient—prepackaged, preferably, and ready-to-eat. This means that we're leaving to commercial foodmakers the peeling, chopping, and mixing of our food. We're buying lettuce in plastic packages and potato salad, tabbouleh, and hummus in deli containers. We're eating out more: Forty cents out of every U.S. dollar spent on food is spent outside the home in restaurants and other commercial food services, where young or inexperienced, and often underpaid, workers are preparing our meals. All of this raises our risks of food poisoning. "The more untrained people handling food, the greater the risk of inadequate cooking or of cross-contamination of safe foods from unsafe or uncooked foods," notes Griffin.
We also like our food cheap. No developed nation spends less of its wealth on meals than the U.S. Advances in technology spurred by pressure to keep food prices low have shifted the balance of food production in the U.S. from many small plants to fewer but larger ones. This magnifies the extent of harm that can arise from a single failure in food safety. In fact, some of the largest and most serious outbreaks of foodborne illness have resulted not from imported foods but from the factories and farms within our own borders, which provide food to huge numbers of consumers.
A 1994 case involving contaminated ice cream constitutes one of the largest outbreaks ever recorded. Trucks transporting the premix for Schwan's, a widely distributed brand of ice cream, carried traces of raw eggs contaminated with Salmonella enteritidis. The outbreak sickened an estimated 224,000 people in 48 states.
One of the deadliest outbreaks on record involved various brands of hot dogs and cold cuts made with meat from a Sara Lee processor. The microbe, an unusual strain of Listeria, sickened scores of consumers in 1998 and was linked to 15 deaths and 6 miscarriages or stillbirths. The outbreak ended after the company recalled 15 million pounds of meat—one of the largest meat recalls in U.S. history.
In the name of efficiency and economy, we have also changed the way we raise our food animals. Our fish, cattle, and broiler and laying chickens are raised in giant "factory" farms, which house large numbers of animals in tight quarters. Griffin and others at the CDC worry that the conditions in these concentrated animal cities favor contamination and the spread of disease.
This is true in cattle feedlots, where animals are held in large groups for fattening before they're brought to slaughter. "Have you ever seen one of these places?" Griffin asks. "The cattle are jammed together, standing on black stuff, which is all feces. By the time they reach the slaughterhouse, they're covered with feces and crowded together. Even if only one animal is carrying E. coli O157:H7, under these conditions it will probably spread to others "
The Jack in the Box outbreak is a case in point. When beef is processed into ground beef, the chances of contamination rise significantly. Processing meat contaminated by one animal can spread the pathogen to all the hamburger that passes through the machinery in one day.
The USDA inspects every carcass in every meat and poultry processing plant—but without checking for microbial pathogens. "Meat inspectors still rely on sight, touch, and smell to spot disease," says Mike Taylor, former administrator of USDA's Food Safety and Inspection Service. "But the real problem in food, the bacteria that make people sick, can't be found that way."
In the summer of 1999, scientists from the USDA visited four large slaughterhouses in the Midwest to test beef cattle for E. coli O157:H7 contamination. The team found that 28 percent of the cattle entering slaughterhouses were infected and 43 percent of the skinned carcasses were contaminated. By the end of processing, however, only 2 percent of the tested meat was tainted, suggesting that measures taken by meat processors may be helping to reduce contamination.
One such measure, put in place in the past several years by food-processing companies, is a system called Hazard Analysis and Critical Control Point (HACCP) plan. This system, overseen by government regulatory agencies, scrutinizes threats to the safety of meat, poultry, seafood, and juice during processing. With HACCP, companies identify the key vulnerable points where contamination can occur in their slaughterhouses or processing plants. They must take steps to minimize the risk of pathogens invading at these points, after which they undergo government auditing.
Many U.S. meat processing plants also address contamination problems with procedures that include chemical baths, rinses, or sprays; bathing carcasses in steam; or irradiating processed meat to kill microbes. But while these measures have likely helped reduce the amount of contamination in meat products, it could be lower still, say scientists, if farmers reduced infection in their livestock. That's no easy task: E. coli O157:H7 is already widespread among cattle herds, and so far there's no proven, effective treatment. Researchers are exploring the possibility of using vaccines against the bug, treating livestock drinking water, even inoculating food animals with healthy gut bacteria to keep the pathogens out.
Patricia Griffin believes that finding E. coli in produce is an even more compelling argument for addressing the food-animal issue than finding it in meat. The problem arises for the most part from manure. "As a society," notes Griffin, "we're extremely careful with human feces. But cattle feces works its way into streams and groundwater, which we use to irrigate and wash our produce. Manure is also used as fertilizer. If it contains E. coli and Salmonella, we are recirculating these pathogens through our environment.
"At least you can kill E. coli in ground beef by cooking it at high enough temperatures," she continues. "But these organisms stick to produce. By washing, you can reduce contamination, but if the pathogenic organisms are there, it's unlikely that you'll get them all off. What are you going to do, not eat lettuce?"
Just how our food animals are becoming infected with these pathogens in the first place remains a mystery. But the answer may lie in what they eat.
Farmers have in the past 50 years shifted the diets of beef cattle from hay to grain in order to boost growth rates and reduce costs. "When ruminants are fed fiber-deficient rations," write USDA's James B. Russell and Jennifer Rychlik of Cornell University, "microbial ecology is altered, and the animal becomes more susceptible to metabolic disorders and, in some cases, infectious diseases."
In addition, new technologies have encouraged the feeding of a wider range of materials to cattle, including wastes. "Chickens in the U.S. eat a variety of feed, including fish meal from Asia," explains Frederick Angulo of the CDC. "Cattle eat such agricultural by-products as peanut hulls, almond shells, waste from bakeries, and poultry manure. These commodities are shipped all over the world.”
By recirculating animal by-products and waste, we may be creating new niches and opportunities for foodborne pathogens to enter the food supply and spread. In Great Britain evidence of the dangers of using animal by-products in livestock feed surfaced in the outbreak of mad cow disease, or bovine spongiform encephalopathy (BSE). The rapid spread of the illness, which likely resulted from feeding cattle meat and bonemeal from animals that already had the disease, was linked with more than a hundred cases of deadly Creutzfeldt-Jakob brain disease in humans who had consumed the infected meat. Since the outbreak among cattle in Great Britain in 1986, BSE has been found in animals in several European countries and Japan.
In 1997 the FDA banned the use of rendered remains of dead cattle and sheep in feed for U.S. ruminants, and there is no sign of BSE yet in the U.S. But many consumer groups are concerned that the government rules for animal feed include too many loopholes. Regulations still allow the use of animal blood and blood products as well as pig and horse protein. They also allow poultry to be used in cattle feed and cattle to be used in poultry feed. Is this an effective recycling of animal protein or a breach in a basic ecologic relationship—with serious consequences for our food supply?
Also present in the troughs of our food animals may be an even greater health hazard than pathogens themselves: antibiotics.
In the summer of 1998 a 62-year-old Danish woman was admitted to the emergency room at a hospital in Copenhagen after suffering diarrhea for nine days. She was diagnosed with foodborne Salmonella and immediately treated with ciprofloxacin, the antibiotic used to treat anthrax and one of the drugs of choice for Salmonella infection. But the drug did little good, and bacteria perforated her intestines. Surgery was unsuccessful, and the woman died of organ failure.
The Salmonella that infected the woman is known in the code language of epidemiologists as DT104. It is a relatively new strain that has evolved resistance to five antibiotics and sometimes shows resistance to those most commonly used to treat the infection it causes. Danish epidemiologists found the DT104 strain of Salmonella in 25 patients, all of whom had either eaten contaminated pork, handled it, or been exposed to someone sickened by it. The meat was traced through a slaughterhouse on the Danish Island of Zealand to two different swine herds. The pigs were carrying bacteria that had acquired resistance to the quinolone class of antibiotics. However, scientists were unable to determine how the pigs had become contaminated.
Farmers have been adding antibiotics to animal feed for more than half a century, after it was discovered that the drugs were effective in accelerating the growth of animals. Now by some estimates the volume of antibiotics used in animal feed equals or exceeds that used in human medicine.
"The promiscuous use of antibiotics as food supplements for farm animals is a serious threat to human health," says CDC's Alicia Anderson, an epidemiologist for the National Antimicrobial Resistance Monitoring System (NARMS). Anderson and others believe that use of the drugs in healthy animals is playing a role in changing the very nature of foodborne bacteria, creating strains that are resistant to antibiotics used in human medicine.
Since the early 1990s infections with the "superbug" DT104 and other foodborne antibiotic-resistant bacteria have turned up in several countries. A report published in 2001 after scientists at the University of Maryland and the FDA sampled ground beef, turkey, chicken, and pork from supermarkets in Washington, D.C., revealed that a fifth of the samples contained Salmonella, and 84 percent of these organisms were resistant to at least one kind of antibiotic. Some were resistant to as many as 12.
Officials in the animal drug industry argue that antibiotics are critical for keeping food animals healthy, and experts agree that overuse of antibiotics among people, not animals, is the true cause of antibiotic resistance in humans. But many scientists say that dosing animals with the same antibiotics we rely on in human medicine is a bad idea. The World Health Organization has advised against the practice, and in 1999 the European Union prohibited four antibiotics used to treat human illnesses from use as livestock growth promoters.
Three of those four antibiotics are still used to treat human illness and to promote livestock growth in the U.S. And at least 13 more are approved for both uses. "We're out of sync with the rest of the developed world in how antibiotics are used," says Anderson.
There are, however, signs of change. In early 2002, three poultry companies announced that they had greatly reduced their use of antibiotics in healthy chickens. Consumer groups and public health officials are hoping that other companies in the poultry, pork, and beef industries will follow their lead.
Government officials and industry representatives are fond of boasting that despite the many threats we have discovered, Americans have the safest food supply in the world. This may or may not be true.
There are indications that since 1996 infections from Campylobacter, Salmonella, and Listeria have dropped slightly—perhaps as a result of consumer awareness combined with new programs in government and industry to ensure the safety of meat, eggs, juice, and fresh produce. Recently government agencies and the food industry initiated a food safety curriculum for students and a "Fight BAC!" campaign to inform consumers how to keep foods safe from harmful bacteria by cleaning them, separating them, cooking them to proper temperatures, and chilling them promptly. And the FDA has launched a training program called Good Agricultural Practices to help other nations train agricultural workers and food producers in safe methods of farming, harvesting, and producing food.
But critics of the nation's food safety net say that gaps created by antiquated, inconsistent laws and regulations as well as fragmented oversight are still allowing too many pathogens to slip into our food supply. Since 1996 more people have gotten sick from Shigella, and the number of deadly E. coli infections has held steady. FDA studies completed in 2001 reported finding either Salmonella or Shigella in 12 out of 1,028 samples of domestic fresh produce, from cantaloupes to scallions, cilantro to celery to lettuce. According to the CDC contaminated eggs caused 82 percent of the cases of Salmonella enteritidis between 1985 and 1998. A study by the Consumers Union a few years ago reported that two-thirds of chickens in U.S. grocery stores carry Campylobacter, bacteria that live in the intestines of healthy birds. When the bacteria survive because of improper cooking of chickens or when cross-contamination occurs in the kitchen, they can cause abdominal pain, fever, diarrhea, and vomiting in humans.
Food is not sterile, and it cannot be made risk-free. But I'm asking myself, Do I accept some level of contamination as inevitable and increase my vigilance in the kitchen? Or do I insist on cleaner meat, poultry, eggs, and vegetables? And how far would I go to get them?
The Swedish chicken industry virtually eliminated Salmonella from their flocks by cleaning up their chicken houses and heating feed to rid it of the pathogen. Now Swedes buy Salmonella-free chickens. Are American consumers willing to pay extra for safer food of higher quality? "Many food producers say no," says Frederick Angulo, director of CDC's NARMS. "But do Americans really know that 10 percent of chickens have Salmonella and 60 to 80 percent have Campylobacter? And that 20 percent of Campylobacter is resistant to fluoroquinolones—the antibiotics of choice for treatment of Campylobacter infections?" he asks. Consumers may understand that cooking chicken properly will kill pathogens, but if they don't know how prevalent those pathogens are in the first place, can they make an informed choice about what to pay for?
Safe food is a moving target—in part because we are moving targets. Our eating habits and our ways of producing food change. We change. In this country the number of people most vulnerable to foodborne disease is growing. Within the next three decades a fifth of the population will be over 65, and many of them will be particularly susceptible to serious infection from Salmonella, Listeria, E. coli. Young children are more likely to be exposed to these bugs than they were a generation ago, not only because the production of food has changed but also because families eat out or take home prepared food more often.
And the microbes themselves are changing, evolving, taking hold in new populations, through new food vehicles, causing more or new disease. We still have limited understanding of how these foodborne pathogens work. After nearly 20 years of research, we still can't consistently treat advanced E. coli O157:H7 infections. We still are searching for clues to how food pathogens spread among cattle, egglaying hens, and broiler chickens.
How can we make safer the food and water that animals consume? How can we dispose of animal manure without threatening the environment and the food supply? How can we ensure the safety of imported foods and foods handled in our restaurants and kitchens?
These are some of the big questions that still need to be addressed to minimize our risk of infection from foodborne disease. In the meantime I am cooking my egg yolks thoroughly, washing my hands and countertops to avoid cross-contamination, and forbidding my children pink hamburger. And I am considering what choices we may have in the future about the safety of our own food, and how much extra I might be willing to pay to have my chicken guaranteed free of Campylobacter—or my salad free of deadly E. coli.
Phenomena: A Science Salon
National Geographic Magazine
Our genes harbor many secrets to a long and healthy life. And now scientists are beginning to uncover them
All the elements found in nature—the different kinds of atoms—were found long ago. To bag a new one these days, and push the frontiers of matter, you have to create it first.
Burn natural gas and it warms your house. But let it leak, from fracked wells or the melting Arctic, and it warms the whole planet.