Experts disagree about whether food is safer today than it was in the past, but they agree that ensuring safe food has become more complex than at any other point in history. Although we have solved many of the food safety challenges of the past, new problems have developed. We farm, live, and eat differently than we did in the past, and this creates new niches for food-borne illnesses to occupy. In addition, there are other potential threats such as food additives, pesticides, hormones in milk and cattle, overuse of antibiotics in farm animals, genetically engineered plants, and risks associated with bioterrorism.
II. U.S. Department of Agriculture
III. Risk Assessment
IV. Hazard Analysis and Critical Control Points
V. Epidemiology and Food-borne Illnesses
VI. Bacteria and Food
D. Escherichia coli
H. Clostridium perfringens
VII. Parasites, Viruses, and Aflatoxins
VIII. Mad Cow Disease
IX. Food Additives and Contaminants
B. Aspartame / NutraSweet
C. Mercury in Fish
XII. Growth Hormones in Beef Cattle
XIII. Recombinant Bovine Growth Hormone
XIV. Genetically Engineered Food
As food safety issues have changed, so have society’s methods for making food as safe as possible. Before manufacturing, traditional farming practices and preserving techniques were used to ensure safe food. During the industrial revolution, food began to be processed and packaged. Lacking regulation, manufacturers were free to add whatever they liked to their products. Sweepings from the floor were included in pepper, lead salts were added to candy and cheese, textile inks were used as coloring agents, brick dust was added to cocoa, and copper salts were added to peas and pickles (Borzelleca 1997, 44). In the 1880s, women started organizing groups to protest the conditions at slaughterhouses in New York City and adulterated foods in other parts of the country. In 1883, Harvey W. Wiley, chief chemist of the U.S. Agricultural Department’s Bureau of Chemistry, began experimenting with food and drug adulteration. He started a “poison squad,” which consisted of human volunteers who took small doses of the poisons used in food preservatives of the time. Wiley worked hard to get legislation passed to regulate what could go into food. Meanwhile, Upton Sinclair spent several weeks in a meat packing plant investigating labor conditions and turned his discoveries into a book, The Jungle, published in 1906. Although the focus of that book was the conditions immigrants experienced in the early 20th century, there were graphic descriptions of the filth and poor hygiene in packing plants. These descriptions of packing plants—not the poor working conditions of immigrants—caught the public’s attention. People began complaining to Congress and to President Theodore Roosevelt. Pressure was also mounting from foreign governments that wanted some assurances that food imported from the United States was pure and wholesome. Two acts were passed in 1906, the Pure Food and Drug Act and the Beef Inspection Act, to improve food safety conditions.
Regulation came only in response to problems: outbreaks and health hazards were followed by new laws. In 1927, the U.S. Food, Drug, and Insecticide Administration (the name was shortened to the Food and Drug Administration, or FDA, in 1930) was created to enforce the Pure Food and Drug Act. However, in 1937, over 100 people died after ingesting a contaminated elixir. The act proved to have penalties that were too light, and the laws were superseded in 1938 by the Pure Food, Drug, and Cosmetics Act. This act prohibited any food or drug that is dangerous to health to be sold in interstate commerce. The Public Health Service Act of 1944 gave the FDA authority over vaccines and serums and allowed the FDA to inspect restaurants and travel facilities. In 1958, concern over cancer led to the adoption of the Delaney Amendments, which expanded the FDA’s regulatory powers to set limits on pesticides and additives. Manufacturers had to prove that additives and pesticides were safe before they could be used. The Fair Packaging and Labeling Act of 1966 standardized the labels of products and required that labels provide honest information. The next major act was the Food Quality Protection Act of 1996. It set new regulations requiring implementation of Hazard Analysis and Critical Control Points (HACCPs) for most food processors. (HACCP is a process where a manufacturing or processing system is analyzed for potential contamination, and systems are put in place to monitor and control contamination at crucial steps in the manufacturing process.) The Food Quality Protection Act also changed the way acceptable pesticide levels are calculated. Now total exposure from all sources must be calculated.
U.S. Department of Agriculture
Growing in parallel to the FDA was the U.S. Department of Agriculture (USDA). The USDA is responsible for the safety of most animal products. In the 1890s, some European governments raised questions about the safety of U.S. beef. Congress assigned the USDA the task of ensuring that U.S. beef met European standards. In 1891, the USDA started conducting antemortem and postmortem inspections of livestock slaughtered in the United States and intended for U.S. distribution. The USDA began using veterinarians to oversee the inspection process, with the goal of preventing diseased animals from entering the food supply.
During World War II, more women entered the workforce and consumption of fast food increased. Ready-to-eat foods like processed hams, sausages, soups, hot dogs, frozen dinners, and pizza increased dramatically. The 1950s saw large growth in meat and poultry processing facilities. New ingredients, new technology, and specialization increased the complexity of the slaughter and processing industry. Slaughterhouses went from being small facilities to large plants that used high-speed processing techniques to handle thousands of animals per day. As a result, food technology and microbiology became increasingly important tools to monitor safety. The Food Safety and Inspection Service, the inspection arm of the USDA, grew to more than 7,000 inspectors. But because of the growth in the number of animals slaughtered and processed, it became impossible to individually inspect each carcass. Without individual inspection, governments and processors must rely on risk-assessment techniques and HACCP to manage these risks. Inspectors must now focus on the production line for compliance, and processing techniques must be strong to compensate for the lack of individual inspection (Schumann et al. 1997, 118).
There are several types of food risks. Eating too much of certain types of foods, such as fats, can be harmful. Eating spoiled or contaminated food can be very dangerous, even deadly. Pesticides and food additives can also pose risks. Risk assessment is the process of evaluating the risks posed and determining whether a food ingredient or pesticide can safely be consumed in the amounts likely to be present in a given food.
In order to compute risks, scientists must consider both the probability and the impact of contracting the disease. A disease with high probability but little impact is of less concern than a disease with high probability and high impact. The object is to either reduce the probability of contracting the disease or the severity of impact. Either action will reduce risk. To evaluate risks, a four-step process is used: hazard identification, exposure assessment, dose-response assessment, and risk characterization.
During the first step, hazard identification, an association between a disease and the presence of a pathogen in a food is documented. For example, contracting dysentery is associated with eating chickens contaminated with Campylobacter jejuni, a type of bacteria. Information may be collected about conditions under which the pathogen survives, grows, causes infection, and dies. Data from epidemiologic studies is used along with surveillance data, challenge testing, and studies of the pathogen.
After the hazard is identified, exposure is assessed. This step examines the ways in which the pathogen is introduced, distributed, and challenged during production, distribution, and consumption of food. Exposure assessment takes the hazard from general identification to all the specific process-related exposures. For example, chickens might become exposed to C. jejuni by drinking unchlorinated water or from other chickens on the farm; the carcass might be exposed during defeathering or on the processing line; the number of pathogens may be reduced in number during the chilling step and increase in number during the packaging step. By examining potential exposure points, the pathogen population can be traced and the likelihood of it reaching the consumer can be estimated.
The third step, dose-response assessment, determines what health result is likely to occur when the consumer is exposed to the pathogen population determined in the exposure assessment step. This step can be very difficult because there may not be good data about what levels of pathogen exposure have health consequences. Another significant factor is the strength of the immune system of the particular consumer. Immune-compromised populations—such as young children, the elderly, AIDS patients, and chemotherapy patients—may react to lower exposure levels and have more severe health consequences.
Risk characterization, the final step, integrates the information from the previous steps to determine the risk to various populations and particular types of consumers. For example, children in general may have a different level of risk exposure than children who consume three or more glasses of apple juice per day. Computer-modeling techniques are often used in this step to ease the computational burden of trying many different scenarios (Lammerding and Paoli 1997). With so many variables, risk assessment does not produce exact, unequivocal results. At best it produces good estimates of the impact of a given pathogen on a population; at worst it over- or underestimates the impact.
Hazard Analysis and Critical Control Points
Hazard analysis and critical control points (HACCP) is a method of improving food safety developed by Pillsbury for the National Aeronautics and Space Administration (NASA) in the late 1950s. HACCP requires determining food safety hazards that are likely to occur and using that knowledge to establish procedures at critical points that will ensure safety. HACCP can be applied at any point in the food cycle from field to fork. The steps, which are modified for each setting, include analyzing the setting for potential problem areas, examining inputs to the system such as suppliers, determining prevention and control measures, taking action when criteria are not met, and establishing and maintaining recordkeeping procedures. Some settings require microbial testing for bacteria.
HACCP is very adaptable to different settings. Rangeland where cattle graze can be managed with HACCP techniques to prevent cattle wastes, which may contain parasites and other potential pathogens, from entering water supplies. The techniques used in this setting include managing stocking rates of cattle to maintain enough vegetative cover, excluding calves from areas directly adjacent to reservoirs, locating water and supplemental feed away from stream channels, maintaining herd health programs, and controlling wild animal populations, such as of deer and feral pigs, that might contaminate the water supply. Regular testing of streams will indicate whether the measures are working, and whether further safeguards need to be undertaken.
Fruit and vegetable producers who grow foods that are often served raw must be especially careful. Their HACCP plans must include worker hygiene plans such as rules for regular hand washing and supplying clean field toilets, adequately composted manure so that pathogens from animal wastes are not spread, testing of incoming water sources, and control of wild animal populations to ensure contaminants are not infecting produce (Jongen 2005).
In a manufacturing plant, HACCP is very compatible with good manufacturing practices (GMPs) that include proper sanitation procedures. HACCP takes GMPs a step further by looking at other potential problem areas. For example, a juice producer following GMPs emphasizes fruit washing, plant cleanliness, and strict adherence to sanitary policies and procedures. To implement HACCP, the plant adds pasteurization to some products, ensures a cold chain by making sure the product always stays cold, and performs microbial testing to make sure the procedures are working.
Jack in the Box restaurants has developed HACCP to a highly refined system since the 1993 Escherichia coli outbreak that resulted from tainted meat from one of its suppliers. Now the restaurant chain does extensive microbial testing—testing the ground beef off the production line every 15 minutes. The distribution company has installed time- and temperature-recording boxes that record the temperature in the delivery trucks to ensure that the beef is always stored at the proper temperature (Steinauer 1997).
In retail food service operations such as restaurants, cafeterias, and in-store deli counters, recipes and procedures must be examined to make food as safe as possible. This examination could result in changing a recipe to ensure that foods that are added raw are chopped in a separate place from other items that are chopped before cooking. Suppliers are carefully examined, food is maintained at the proper temperature, and the length of time foods are left out is closely monitored. For example, a policy that unsold chicken nuggets will be thrown out every half hour might be implemented with a timer that beeps on the half hour. Employees might have to initial a log stating that they had disposed of unsold food.
HACCP has been mandatory since the 1970s for the low-acid canned food industry and went into effect for domestic and imported seafood processing in 1997. Meat and poultry processors had to implement HACCP plans in January 2000. Since requiring producers to implement HACCP plans, the USDA’s Food Safety and Inspection Service (FSIS) and the FDA have used HACCP as a powerful tool to monitor contaminant levels and require changes to plans in order to reduce hazards. For example, in late 2003, after the FSIS required ready-to-eat-food processors to improve their HACCP plans, the FSIS released data showing that regulatory samples showed a 70 percent decline in the number of samples testing positive for Listeria monocytogenes. And in October 2002, the FSIS required all raw beef processing plants to reassess their HACCP plans to reduce the prevalence of E. coli O157:H7 bacteria in ground beef. As a result, 62 percent of the plants made major changes to their processing lines. Percentages of regulatory samples testing positive dropped almost two-thirds from 0.86 percent in 2000 to 0.32 percent in 2003 (U.S. Department of Agriculture, Food Safety and Inspection Service 2004).
Epidemiology and Food-borne Illnesses
Most of what is known about food-borne illnesses started with epidemiology, the study of disease in a population. John Snow, a London physician, used deductive reasoning, research, and interviews in the 1880s to determine the cause of a cholera epidemic that had killed more than 500 people in one week. Scientists used Snow’s techniques to investigate primarily infectious disease until the 1920s, when the field broadened to include clusters of all factors that apply to the incidence of disease among people.
Epidemiological techniques have improved over the years. In the 1970s, Dr. Paul Blake developed the case-control method. This method compares those who became ill with closely matched individuals who stayed well. By examining what those who became ill did differently from those who stayed well, the source of infection can often be revealed. In the case of food-borne illness, an ill person is questioned about where and what they ate and matched as closely as possible in age, health status, and eating patterns to someone who stayed well in an effort to pinpoint differences.
In the United States, the Centers for Disease Control and Prevention (CDC) works to help treat and prevent disease at the national level, and has increased its scope to lend epidemiological assistance worldwide because of the overlap between the developed and less developed worlds. The people who pick and pack fruits and vegetables in foreign countries that are imported to the United States are handling the U.S. food supply. If foreign workers have illnesses that can be transmitted through food, their illnesses have a direct bearing on our health.
Food-borne illness is most often linked to bacteria, but there are other agents that can cause food-borne illness, including viruses, parasites, prions, and molds. Bacterial illness is the most prevalent, but viruses and parasites are being spread through food more commonly than in the past. Each type of disease agent has different characteristics that must be considered in implementing food safety strategies.
Bacteria and Food
The Centers for Disease Control and Prevention estimate that 79 percent of food-borne illness is caused by bacteria. Bacteria, small microorganisms that do not have a nucleus, can replicate in food, water, or in other environmental media. Some bacteria do not grow well in cold temperatures, while others flourish. Some bacterial strains are extremely virulent, causing infection with as little as two bacteria. Other bacteria must be present in large numbers to cause any problems. The most common way food-borne bacterial illness is transmitted is the fecal–oral route, where fecal matter from an animal or person contaminates foodstuffs. This contamination could result from inadequate hand washing, fecal matter from animals being transferred to meat during the slaughter or processing steps, or even unsterilized manure being used to fertilize crops. Harmful bacteria can also be carried in animals and, even without fecal contamination, can be present in meat or eggs.
One of the most helpful tools scientists have developed to investigate bacterial illnesses is DNA fingerprinting. Each strain of bacteria has a unique genetic fingerprint. By comparing bacteria from ill persons with bacteria from suspected foods, it is possible to definitively conclude whether that particular food is the causative agent of the disease. This tool has helped health departments tremendously to trace the source of infection and limit outbreaks. The following list identifies the major bacterial illnesses.
Campylobacter is the most common bacterial food contaminant, prevalent in a variety of food animals but most often associated with poultry. Meat becomes contaminated when it comes in contact with fecal matter from an infected animal. In humans, Campylobacter can cause bacteremia (bacteria gets into the bloodstream), hepatitis, pancreatitis, septic arthritis (bacteria gets into the joints and causes stiffening), and Guillain-Barre syndrome (GBS).
Listeria monocytogenes is a particularly pernicious bacteria found in soil and water that can survive refrigerator temperatures and even freezing. It can be found on some vegetables as well as on meat and dairy products. Listeria can cause septicemia, meningitis, encephalitis, and intrauterine or cervical infections in pregnant women that may cause miscarriages or stillbirths. Of the 2,500 cases reported annually in the United States, about 500 die.
Salmonella is the second most common source of food poisoning in the United States after Campylobacter. It is most often associated with raw eggs and undercooked poultry, although it also can contaminate vegetables, fruits, and other products. Salmonella generally causes sudden headache, diarrhea, nausea, and vomiting. Symptoms may be minor or severe, causing dehydration or even death. The CDC estimates there are 2 to 4 million cases each year resulting in 500 to 1,000 deaths. (U.S. Food and Drug Administration 2005). Some strains of Salmonella are becoming resistant to antibiotics.
Escherichia coli is a type of bacteria that thrives in our intestines and helps digest food. Most strains are beneficial, but a few release harmful toxins that can cause great discomfort and even death. There are four classes of E. coli that cause illness in humans, the most toxic being O157:H7. Scientists believe the toxin first destroys blood vessels in the intestines, causing bloody diarrhea. Most people recover, but about 2 to 7 percent develop hemolytic uremic syndrome (HUS). About 5 percent of those who contract HUS die, and many survivors of the disease are left with lasting problems such as diabetes, kidney damage, visual impairment, or a colostomy (Kluger 1998). E. coli O157:H7 is most commonly associated with cattle, transmission usually occurring during the slaughter process when fecal matter from the intestines can contaminate the meat. Heat kills the bacteria, but the cooking of meat must be thorough and must reach an internal temperature of 160 degrees Fahrenheit to be safe.
Shigella causes a little less than 10 percent of all food-borne illness in the United States. Shigellosis (the disease caused by Shigella) can cause abdominal pain, cramps, diarrhea, fever, and vomiting. It is often found in prepared salads, raw vegetables, milk, other dairy products, and poultry (U.S. Food and Drug Administration 2005).
Yersinia pseudotuberculosis is rare in the United States but can be found in meats, including beef, pork, lamb, oysters, and fish, and also in raw milk. Although most people recover quickly from yersiniosis, about 2 to 3 percent develop reactive arthritis (U.S. Food and Drug Administration 2005).
Foods that require lots of handling during preparation and are kept at slightly elevated temperatures after preparation, including prepared egg, tuna, macaroni, potato, and chicken salads, and bakery products like cream-filled pastries, are frequently carriers of Staphylococcus aureus. The usual course of the disease is rapid onset of symptoms including nausea, vomiting, and abdominal cramping. Although the number of reported cases is relatively low (usually less than 10,000 per year in the United States), the actual number is probably much higher since many cases go unreported because the duration of the illness is very short, and the symptoms are not that severe (U.S. Food and Drug Administration 2005).
Clostridium perfringens is an anaerobic bacteria present in the environment and in the intestines of both humans and domestic and feral animals. Since the bacteria are so prevalent, most foods are contaminated with it, especially animal proteins such as meat. However, the small amounts of C. perfringens in foods do not cause any problems unless the food is not cooled down quickly enough or stored properly. The CDC estimates that about 10,000 cases occur each year, most of them in institutional settings like hospitals, school cafeterias, prisons, and nursing homes. The illness causes intense abdominal cramps and diarrhea (U.S. Food and Drug Administration 2005).
Parasites, Viruses, and Aflatoxins
Perhaps the best-known parasite in the United States is Trichinella spiralis, a small roundworm found in raw pork that causes trichinosis. Early symptoms include diarrhea, vomiting, and nausea. These can be followed by pain, stiffness, swelling of muscles, and swelling in the face. Thiabendazole effectively kills the parasites in the digestive tract, and anti-inflammatory drugs can ease the symptoms (U.S. Food and Drug Administration 2005).
Although Trichinella has been well understood for years, it does not cause as much food-borne illness as three other parasites: Giardia lamblia, Cryptosporidium parvum, and Cyclospora. These waterborne parasites can be transferred to food from infected food handlers or from contaminated water used to irrigate or wash fruits or vegetables.
Another source of parasites is raw seafood. The Japanese suffer from high rates of nematode infection resulting from high rates of consumption of raw fish. It occurs less frequently in the United States, where raw fish consumption is moderate. One of the worms, Eustrongylides species can be seen with the naked eye and causes septicemia. Other worms are much smaller. Well-trained sushi chefs are good at spotting the large parasites, but other techniques are necessary to protect against the smaller ones. Blast freezing is one of the techniques that kills parasites. The USDA Retail Food Code requires freezing for all fish that will be consumed raw. The exception is tuna, which rarely contains parasites. Often fish get parasites from eating smaller fish that have the parasites. Fish raised in captivity and fed fish pellets rarely have parasites. High-acid marinades do not affect parasites, so they should not be used as a substitute for cooking or freezing (Parseghian 1997).
Viruses, like parasites, pose great problems for food safety because they are environmentally stable, are resistant to many of the traditional methods used to control bacteria, and have low infectious doses. So virtually any food can serve as a vehicle for transmission. It is not clear just how pervasive food-borne viral illnesses are, partly because viruses are difficult to test for. The most common viral diseases spread by food are hepatitis A and noroviruses.
Over one hundred dogs died early in 2006 from Diamond-brand dog food contaminated by aflatoxins (Aflatoxin Poisoning 2006). Aflatoxins are naturally occurring toxic byproducts from the growth of Aspergillus flavus fungi that grow on grains and groundnuts such as corn, wheat, barley, oats, rice, and peanuts. The toxins are a sporadic problem for U.S. farmers.
Mad Cow Disease
Bovine spongiform encephalopathy (BSE) is a disease that strikes cows causing them to develop spongy areas in their brains and suffer neurological damage. It seems likely that the cows get the disease from eating sheep brains contaminated with scrapie, a similar disease found in sheep. (Sheep’s brain tissue is rendered into cattle feed.) When BSE was first noticed in the United Kingdom in 1986, some cows were found staggering around in circles, hence the name mad cow disease. By 2006, more than 184,000 cows in 35,000 different herds had been diagnosed with the disease and more than 4 million had been destroyed in an attempt to wipe out the disease (U.S. Department of Health and Human Services 2006). In addition to the toll on cattle, humans began developing a related disease, Creutzfeldt-Jakob disease. Scientists determined that people who had consumed brain or spinal tissue from cows were getting the disease (Easton 2005). Today, both internationally and in the United States, there are safeguards in place to prevent BSE from infecting herds and to keep prions (protein molecules thought to lie at the heart of the disease) from entering the food supply.
Food Additives and Contaminants
Before the U.S. Food and Drug Administration (FDA) approves a new food additive or ingredient, its safety must be demonstrated. Animal feeding studies are performed to determine safety. Large doses are fed to a small number of rats to see whether they develop cancer or other diseases. Olestra and aspartame (marketed as Equal or NutraSweet) have caused the most debate in recent years.
Olestra, a fat substitute, was first synthesized at Procter & Gamble in 1968. Chemically, olestra is a table sugar (sucrose) molecule to which as many as eight fatty acid residues are attached. The molecule is so large and fatty that it cannot be broken down by the intestinal enzymes and absorbed by the body. Since it cannot be absorbed by the body, it is used as an indigestible fat substitute in the manufacture of low-calorie foods. Although in the early 1990s researchers discovered that eating even small amounts, such as the quantity in one ounce of potato chips, could cause digestive problems (diarrhea, abdominal cramping, gas, and fecal incontinence), the FDA approved olestra in 1996 for savory snacks such as chips, crackers, and tortilla chips. Because of the adverse effects, however, products had to carry a warning label. Consumer complaints nevertheless began to roll into the FDA; the agency had received almost 20,000 complaints about olestra by 2002, more than all other consumer complaints about other food additives combined (Center for Science in the Public Interest 2006). In 2003 Procter & Gamble lobbied the FDA to remove the warning label for foods containing olestra. The FDA granted the request despite lobbying by consumer groups that wanted the labels to stay.
Aspartame / NutraSweet
Aspartame, sold under the brand NutraSweet, was discovered accidentally by a scientist at Searle in 1965 (Bilger 2006). Today, it is a widely used sweetener that is part of more than 6,000 processed foods including sodas, desserts, candy, and yogurt. There have been some concerns about the safety of aspartame, however. Some people have reported dizziness, hallucinations, and headaches after drinking diet sodas made from aspartame. An independent study confirmed that aspartame can cause headaches in some individuals. Ongoing research suggests that aspartame is probably safe, especially in moderate quantities, like one packet of Equal or one diet soda per day, but individuals who experience headaches or those with the rare disease phenylketonuria (PKU) should avoid it.
Mercury in Fish
Mercury, a toxic metal, makes its way into our oceans from the atmosphere. Mercury is emitted by some natural processes, but it mostly enters the atmosphere from mining and smelting of mineral ores, combustion of fossil fuels, incineration of wastes, and from the use of mercury itself. Mercury is extremely hazardous and causes both neurological and heart problems. The FDA set guidelines for permissible levels of mercury in 1969 (Hawthorne and Roe 2005).
Mercury is a chemical which bioaccumulates, so older fish and fish that live higher on the food chain have higher concentrations of mercury in their systems. In 2004 the EPA and FDA issued a joint warning statement about fish. Children, pregnant women, and women of childbearing age are advised to avoid shark, swordfish, king mackerel, and tilefish because of high levels of mercury and to eat no more than 12 ounces of fish per week total. Further, the agencies recommend that this group of consumers eat only low-mercury fish such as shrimp, canned light tuna, pollock, and catfish. Albacore tuna is higher in mercury and should be avoided by this group.
Many states have issued their own safety warnings to further protect their citizens. Washington State reviewed the FDA’s data and concluded that women of childbearing age and children younger than six should not eat fresh or frozen tuna at all, and should limit their canned tuna consumption based on body weight. California requires supermarkets to post warnings in their stores, and Wisconsin and Minnesota recommend at-risk groups limit consumption of halibut, tuna steak, and canned albacore to two meals per month (Hawthorne and Roe 2005).
Salmon is the third most popular fish food in the United States behind canned tuna and shrimp. Ninety percent of the salmon consumed is farm raised (Burros 2005b). In 2003, the Environmental Working Group tested farm-raised salmon for PCBs, an industrial pollutant and known carcinogen. These tests revealed that whereas PCB levels in wild salmon averaged 5 parts per billion (ppb), farmed salmon levels averaged 27 ppb. EPA guidelines recommend eating fish with PCB levels that are no higher than 4 to 6 ppb, based on consuming two fish meals per week (Burros 2003a). In follow-up studies, including a large study funded by the Pew Charitable Trust’s Environment Program, scientists found large differences in contaminant levels between farmed and wild salmon. The Pew study sampled about 700 salmon from around the world and analyzed them for more than fifty contaminants, including PCBs and two other persistent pesticides, dieldrin and toxaphene. All three of these contaminants have been associated with increased liver and other cancer risk. Using EPA guidelines, the scientists determined how much salmon could be consumed before cancer risks increased to at least 1 in 100,000. For the most contaminated fish, from farms in Scotland and the Faroe Islands, that amounted to 55 grams of uncooked salmon per month, about a quarter of a serving. The cleanest fish are raised in Chile and the state of Washington. One serving can be consumed per month without increasing cancer risk.
There are more than 865 active ingredients registered as pesticides in the United States. These are formulated into thousands of pesticide products. The EPA estimates there are 350 different pesticides that are used on the foods we eat and to protect our homes and pets (U.S. Environmental Protection Agency 2006). Pesticides can be naturally occurring substances such as nicotine, pyrethrum (found in chrysanthemums,) hellebore, rotenone, and camphor, or synthetically produced substances such as inorganic chemicals, metals, metallic salts, organophosphates, carbamates, and halogenated hydrocarbons.
Before a company can market a pesticide in the United States, it must demonstrate to the FDA that it is safe. The FDA determines what concentration levels of a pesticide or its breakdown products are safe. The tolerance levels, the amount allowed to be present on food at harvest, were adjusted by the 1996 Food Quality Protection Act to be based on what levels are safe for children. Some researchers, however, have criticized the methodology used by the EPA and the FDA to determine pesticide safety because it is limited to testing for cancer, reproductive outcomes, mutations, and neurotoxicity. Further, the EPA does not consult the scientific peer-reviewed literature of studies done on pesticides, but relies on the manufacturer’s gross feeding studies instead. For example, one meta-study analyzed the results of 63 separate studies that showed that certain pesticides affect the thyroid. (The thyroid controls brain development, intelligence, and behavior.) Yet the EPA has not acted to ban any pesticides due to thyroid effects (Colborn 2006).
In 1949 Dr. Thomas Jukes, then director of Nutrition and Physiology Research at Lederle Pharmaceutical Company, discovered that animals fed small doses of antibiotics gained weight faster. In the early 1950s farmers began to incorporate antibiotics into livestock feed to both promote growth, and thus cut production costs, and also to treat subclinical diseases—diseases that do not cause obvious symptoms but nevertheless are taxing to the animal. Use of antibiotics remained strong, and according to a 2001 report, approximately 70 percent of the 24.5 million pounds of antibiotics used in the United States are administered to livestock for nontherapeutic purposes (Union of Concerned Scientists 2001). Scientists began to realize that the use of antibiotics in this way was not without consequences, however. In 1969 the Swann committee in England recommended that antibiotics only be used to treat animals when prescribed by a veterinarian. Further, the report stated that penicillin and tetracycline should not be used at subtherapeutic doses for growth promotion. In the early 1970s, most Western European countries banned the two drugs for livestock use, but the United States did not. Since the Swann report, many other research bodies have made similar conclusions about antibiotic use in livestock including the National Research Council Committee on Drug Use in Food Animals, which identified uses of antibiotics in food animals that could enhance development of antimicrobial resistance and its transfer to pathogens that cause human disease (Swartz 2002).
The European Union decided to phase out antimicrobials in food for growth promotion. The final phase went into effect in 2006, and now drugs are no longer allowed. In Denmark, where use of antibiotics in healthy animals was banned years earlier, farmers were able to reduce their use of antibiotics by over 50 percent (some antibiotics are still needed to treat sick animals), and the costs of additional feed were minimal (Wegener 2002). The National Academy of Sciences estimated that eliminating antibiotics in healthy animals would cost consumers from $5 to $10 annually in higher food costs (Keep Antibiotics Working 2006).
In the United States, many groups like the American Medical Association, the American Pediatrics Association, and the American Public Health Association, as well as more than 350 consumer, environmental, and sustainable agriculture groups, do not think the FDA has gone far enough in regulating antibiotics. Two consortium groups, Keep Antibiotics Working and the Alliance for the Prudent Use of Antibiotics, put together a Senate bill in 2007 to ban the use of seven classes of antibiotics for growth promotion that are used to treat humans: penicillins, tetracyclines, macrolides, lincosamides, streptogramins, aminoglycosides, and sulfonamides. It would also restrict any use of a drug that subsequently became important in human medicine. Sick animals, however, could still be treated with the drugs when prescribed by a veterinarian.
Today, four of the nation’s top chicken producers, representing 38 percent of the total chicken market, have stopped using antibiotics for growth promotion. Tyson Foods, Gold Kist, Perdue Farms, and Foster Farms also restrict antibiotic use for routine disease prevention. McDonald’s Corporation and other large-scale purchasers, such as Bon Appetit Management Company, the fourth-largest food service company in the United States (the company services colleges and universities as well as corporate food service operations), were part of the impetus to reduce antibiotic use (Weise 2006).
Growth Hormones in Beef Cattle
Since the 1950s, growth hormones have been used to increase meat production. Three naturally occurring hormones—estradiol, progesterone, and testosterone—and their synthetic equivalents—zeranol, melengestrol acetate, and trenbolone—are injected into calves’ ears as time-release pellets. This implant under the skin causes the steers to gain an extra two to three pounds per week and saves up to $40 per steer in production costs, because the steers gain more weight with the same amount of feed. Two-thirds of U.S. cattle are treated with hormones, but the European Union banned the practice in 1988 and bans imported beef unless it is certified hormone-free (Raloff 2002).
There is wide disagreement about whether the practice is safe. Hormone-like chemicals (DDT, PCB, dioxin, etc.) in large enough concentrations or at critical points in fetal development disrupt functioning of the natural hormones in both animal and human bodies. The U.S. government has been studying the endocrine disruptive effects of certain estrogenic (estrogen-producing) pesticides and food contaminants known as xenoestrogens (substances that behave like estrogens), but has only begun to study the effects of hormones in meat and its impact for food safety and the environment. There has been escalating incidence of reproductive cancers in the United States since 1950. However, it is difficult to say whether added hormones in beef are linked to additional cancer cases, as some believe, or whether the causes are from something else entirely, such as eating a diet rich in animal protein. The hormones in meat are trace amounts. Nevertheless, the European Commission Scientific Committee for Veterinary Measures Relating to Public Health concluded that adverse effects from hormones include developmental, neurobiological, genotoxic, and carcinogenic effects. They further concluded that existing studies do not point to any clear tolerance level, and thus banned the hormones outright (European Commission Finds 1999). The U.S. beef industry argues that the natural hormone levels in the aging bulls and dairy cows used for beef in Europe can be many times higher than from steers treated with hormones.
Recombinant Bovine Growth Hormone
Similar controversy surrounds recombinant bovine growth hormone (rBGH), also called recombinant bovine somatotropin (rBST), administered to dairy cattle to help them produce more milk. Developed by the Monsanto Corporation and marketed under the name Posilac, it has generated a lot of debate since it was approved by the FDA in 1993. The United States is the only major industrialized nation to approve rBGH. Health Canada, the food and drug regulatory arm of the Canadian government, rejected rBGH in early 1999 and stirred up more controversy in the process. They rejected the drug after careful review of the same data that was submitted to the U.S. Food and Drug Administration, finding that it did not meet standards for veterinary health and might pose food safety issues for humans.
The hormone is injected into the pituitary gland of dairy cows every two weeks because it can increase milk production by as much as 15 percent. The mechanism by which rBGH works may, however, create dangerous hormones for people consuming the dairy products from treated cows. As a by-product, rBGH causes cows to produce more insulin growth factor 1 (IGF-1). IGF-1 is present in milk at higher levels in cows that take rBGH. IGF-1 causes cells to divide. Elevated levels have been associated with higher rates of breast, colon, and prostate cancer. Studies show that IGF-1 survives the digestion process, and the added levels in milk may cause additional cancers in humans. As part of the Nurses Health Study conducted by Harvard University, researchers analyzing the study data concluded that “the results raise the possibility that milk consumption could influence cancer risk by a mechanism involving IGF-1” (Burros 2005a).
The U.S. Department of Agriculture (USDA) estimates that approximately 22 percent of the dairy cows in the United States are treated with rBGH, but FDA rules do not permit a dairy to declare its milk rBGH free. Only milk labeled organic is assured to have no rBGH. Most milk is pooled so almost all the U.S. milk supply has at least traces of rBGH.
Genetically Engineered Food
The latest method of improving productivity is genetic engineering: the transfer of DNA from organisms of one species into organisms of a different species. These DNA transfers can be used to make crops pest-resistant, unaffected by herbicides, or with enhanced nutritional qualities. For example, Monsanto inserted a bacterium into potatoes that causes the potato to be starchier. These starchier potatoes absorb less fat during frying, creating lower-fat french fries and potato chips. Monsanto is also currently experimenting with soybeans to change the type of oil found in soybeans to the omega-3 fatty acids found in fish, but without the fish taste, giving consumers the possibility of getting the health benefits of omega-3s without consuming fish. (The American Heart Association recommends consumers eat two servings of fish weekly, yet only 17 percent of the U.S. population eats that much fish) (Melcer 2006).
So far scientific studies have not shown major problems with genetically engineered foods, but there may be long-term, unforeseen consequences when the environment is changed. In many other areas, changes in the ways food is grown and processed have created niches for harmful bacteria and viruses. Genetic engineering has much to offer in increasing the amount of food available to the world’s expanding population, but the process should be carefully reviewed and tested to avoid creating new food risks and environmental catastrophes.
Just as science has brought us new food production techniques, it has also brought new food safety strategies, such as irradiation. Irradiation is the process of subjecting food to electron beams or gamma rays to kill bacteria. The radiation damages the bacteria so that it cannot reproduce. By killing the bacteria, spoilage is also delayed. The amount of radiation is not enough to make the food radioactive, only to kill bacteria. Currently irradiation is used to sterilize medical supplies and cosmetics and a limited number of foods.
Irradiation is the only way to kill E. coli O157:H7 besides heat. After the four deaths of children from E. coli O157:H7 that were traced to Jack in the Box restaurants in 1993, enthusiasm for irradiation grew and the USDA approved irradiation of beef in 1999. Irradiation raises the cost of meat by up to 20 cents per pound (Gersema 2003).
Meat producers have been cautious about introducing irradiated beef because of the added cost and because it can darken meat and change the flavor enough to be noticeable. High-fat foods can develop a rancid smell. Irradiated food must be marked with the Radura symbol or it must say irradiated on the food label. The marketing departments of the grocery and meat trade organizations have found that considerable education of consumers is needed before they will accept irradiated food. The FDA expanded the definition of pasteurization in 2004 to be “any process, treatment, or combination thereof that is applied to food to reduce the most resistant microorganism(s) of public health significance to a level that is not likely to present a public health risk under normal conditions of distribution and storage” (Sugarman 2004). This new definition allows irradiated food to be labeled “pasteurized” as well as food sterilized by a host of new and old technologies such as pulsed electric fields, ohmic heating, high-pressure processing, and regular cooking processes. However, the word irradiation would still have to appear, as in “pasteurized with irradiation.” Market demand will have to be seen in order for investment to be made in the large-scale facilities that would be needed to process large quantities of food.
Besides increased cost and potential reduction of food taste, there are several drawbacks to irradiation. When the food is bombarded with radiation, some of the electrons are freed and attach to other atoms forming new compounds, some of which are harmful, like benzene and formaldehyde. There is also significant vitamin loss from irradiation. Vitamins A, B1, B3, B6, B12, C, E, and K and folic acid are affected. In some foods, as little as 10 percent of the vitamins are destroyed, but in others it can be as high as 50 percent. If irradiated foods become a major part of people’s diets, overall nutritional quality will suffer. And while irradiation kills most bacteria, it does not affect viruses, and any bacteria that get onto food after treatment suddenly have a food supply without any competitors. This creates the potential for very toxic food (Fox 1998).
Since the terrorist attacks of September 11, 2001, all sectors of the United States have considered vulnerability to terrorism, and the food industry is no exception. Food and the agricultural industry do provide a potential avenue for terrorist attacks, although no one knows how likely such an event is to occur. Some researchers think it would be unlikely to occur, but others think there is potential for bioterror depending on the objectives terrorists were trying to achieve.
Agricultural and food-chain assaults do not have the immediacy and impact of human- directed atrocities such as bombings. The impacts are delayed, and may lack a single focus-point for media attention. The hostility and panic surrounding the September 11 attacks were derived in part by the drama of the suicide bombings, whereas agricultural terror and food tampering are slower to get going but can still be quite devastating. Controlling access, using tamper-resistant or tamper-evident systems such as tape or wax seals, and keeping records so that tracing and recall of animal feeds can occur all enhance food security at the product level. The FDA created industry recordkeeping requirements in 2004 so that in the event of an outbreak officials will be able to track the source of the food (Alonso-Zaldivar 2004).
Nina E. Redman
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