SECTION 3: Hazards in the Food System

  • Overview of the Hazards
  • Chemical Hazards
  • Physical Hazards
  • Biological Hazards
  • Potential Pathogens in Food



    Overview of the Hazards
            The concept of HACCP was developed by National Aeronautics and Space Administration (NASA) and the Natick Laboratories in the early 1960s with the cooperation of the Pillsbury Company to supply safe food products to be used by astronauts in space (179).  In 1971, the concepts of risk assessment (hazard analysis) and critical control points were merged at the National Conference on Food Protection (146).
            The Pillsbury Company was the first company to employ HACCP as a means of increasing the probability to near 100% that foods produced by the company would be safe.  The Pillsbury Company developed a HACCP program (13, 144) that included the assessment and control of chemical, and physical hazards in food as well as microbiological hazards.  The ICMSF (International Commission on the Microbiological Specifications for Foods) Microorganisms in Foods 4:  Application of the Hazard Analysis Critical control Point (HACCP) System to Ensure Microbiological Safety and Quality, (90) focuses only on microorganisms (biological hazards) in food.
            Actually, many hazards are found in the food environment.  Hazards are identified from insurance liability claims and medical records showing what has caused illness and injury in people in a specific environment.  The goal of HACCP is to provide safe food for consumers today, and continually reduce the risk of a critical control failure so that the food will be even safer tomorrow.  When this goal is met, the risk of causing a foodborne illness is near 0%, producer liability costs are diminished, and the resources of governmental and medical agencies are conserved.
            Note that discussion of chemical and physical hazards is first, because these hazards are typically handled by the prerequisite programs, whereas the biological hazards are handled by the food process controls.  What are the hazards to be controlled?  Table 3-1 provides an overview of the hazards in food that can harm people.

    Chemical Hazards
                Hazards in food include chemical compounds that, when consumed in sufficient amount, can inhibit absorption and/or destroy nutrients; are carcinogenic, mutagenic, or teratogenic; or are toxic and can cause severe illness and possibly death because of their toxological effect on the human body.
            Poisonous substances.  The following is a summary of poisonous substances that may be present in food.
          Toxic plant material.  This includes solanin in potatoes; hemagglutinins and protease inhibitors present in raw beans and peas; cyanogens in fruit kernels; and phytoalexins in sweet potatoes, celery, and parsnips.  Fortunately, many of these compounds can be eliminated by preparation methods.  For example, solanin is eliminated when the green surface portion of potatoes is peeled or trimmed.  Fruit seeds and fruit pits containing cyanogens are usually discarded.  Hemagglutinins and protease inhibitors in raw plant seeds are altered by cooking with moist heat and thus, become harmless.
          Intentional food additives include GRAS (Generally Recognized As Safe) compounds that may have inadvertently been added in excessive amounts.  Examples include excessive addition of nitrites and nitrates in processed meats, excessive use of monosodium glutamate in prepared foods, and excessive use of sulfites in permitted-use items such as dried fruits and wine.  Another example is the intentional addition of an undisclosed ingredient.  For instance, addition of peanut butter to a product without disclosure could result in fatal anaphylactic shock for sensitized individuals.
          Chemicals created by the process include those created when meat is broiled excessively over hot charcoal and chemical compounds created when fat or oil has been heated excessively or for a long time.
          Agricultural chemicals include pesticides and herbicides.  In 1985, Foster and Kaferstein (60) pointed out that, with the increased utilization of chemicals in agriculture and animal husbandry, the chances of chemical food contamination are growing throughout the world.  Agricultural chemicals have a great impact on water systems.  When it rains, these toxic substances are carried into rivers and lakes, affecting fish and aquatic plant life as well as water supplies.
            Animal antibiotics and other drug residues are also a problem in terms of foodborne illness hazards.  In 1990, the USDA sampled 35,561 livestock for drug residues and found residual levels in 132 samples.  The USDA examined 9,132 poultry samples and found residues in 12 samples (26).  Drug residues in food can cause violent allergic reactions in sensitized people who consume these products.
            Unintentional additives or accidental addition of toxic substances during food handling in the foodservice and food production operations can also occur. This type of hazard is often traced to storage of caustic or toxic cleaning and sanitizing chemicals in food storage containers.
            Equipment material such as copper or lead from pipes or soldering material can leach into food and water to cause heavy metal poisoning.
            Package material can leach as well.  In the U.S., in the past, there was concern about the leaching of lead from the solder of can seams and polychlorinated biphenols from cardboard packages.  These concerns have decreased in the U.S., because these compounds have been almost completely eliminated from packaging systems.  However, these types of packaging material may still exist in other regions of the world.  There is also concern over the safety of certain plastics, especially those that may be used in the heating or reheating of foods in a microwave oven.
            Heavy metals and radioactive isotopes from the industrial environment can also find their way into food, usually through water sources.  An example of this is the level of mercury in fish taken from lakes and rivers.
            Sometimes a poisonous substance in food can be controlled (diminished to a minimal risk) if the food is washed or is heated (cooked) sufficiently.  However, the best strategy is for the food operator to keep harmful substances out of food by purchasing supplies produced under controlled or known growing, harvesting, processing, and storage conditions.
            Adverse food reactions.  About 1% of the population is allergic to compounds (usually certain proteins) found in food.  Allergic reactions may be caused by many types of foods, including milk, eggs, fish, seafood (particularly shrimp), legumes (peanuts), tree nuts, and wheat.  Other foods, including citrus fruit, melons, bananas, tomatoes, corn, barley, rice, and celery, can cause allergic reactions in a few sensitized individuals (183).  In hospitals especially, the medical personnel develop sensitivities to latex in gloves, and if a food worker prepares food using latex gloves, that can be enough transfer of latex to cause a reaction in the food consumer.
            Allergic reactions vary with each individual's sensitivity.  Some allergic reactions are mild (e.g., watery eyes, nasal discharge, headaches, etc.).  However, some people are very sensitive.  If they consume an offending food, life-threatening anaphylactic shock can occur within minutes after the food is consumed.  There must be emphasis on training staff to understand the serious nature of food allergies.  Personnel must know, or be able to find, an accurate list of all ingredients in food served to customers.  Complete disclosure of ingredients used to prepare food should be available to hypersensitive individuals if they request this information.  Personnel must recognize that even cross-contact of one food by another can pose a problem for highly sensitive individuals.
            In the United States, prepared foods must have an ingredient label.  Labeling of food and disclosing recipe ingredients enables hypersensitive people to avoid foods with offending components.  The use of kitchen chemicals such as MSG (monosodium glutamate), food color (yellow dye #5), and aspartame in food items should be disclosed if customers request this information.
            Nutrition, or lack of it, is a health problem.  The health of people is particularly important in disease prevention and is partially dependent on a properly balanced, nutritious diet.  If this is not provided to people, the quality of life and life expectancy are seriously diminished.  Both macro- and micro-nutrients, in required amounts, are necessary to promote and maintain health in humans.  In many developing countries, lack of an adequate supply of food contributes to malnutrition and a decreased health status of the general population, particularly infants and children.  As a result of this, a large portion of the population is susceptible to infection and disease.
            Nutritional hazards in food products include:
    1. Nutritional deficiencies and/or inaccurate formulation of a food can cause illness complications and possibly death in infants, elderly, and critically ill or injured individuals.
    2. Anti-nutritional factors such as phytates in green, leafy vegetables and trypsin-inhibitors in legumes, and soybeans must be taken into account in food production and food preparation.
    3. Destruction and unnecessary loss of nutrients occur when foods are processed for long periods of time and stored improperly.  The nutrient most notably susceptible to destruction is ascorbic acid.  Ascorbic acid loss in cooked vegetables is high if these foods are left on steam tables for long periods of time.  The B-vitamins are also unstable under various process conditions.
    Physical Hazards
            Hard foreign objects include:  fragments of glass; wood; stones; metal fragments; packaging materials; bones and bone fragments; building material; filth from insects, rodents and any other unwanted animal parts or excreta (that is already on the food from the farm); and personal effects (earrings, jewelry fragments).
            The most definitive report on this subject is that of Hyman et al., 1993 (89).  This report was a careful analysis of 10,923 complaints about food registered with the FDA for one 12-month period.  Of these complaints, 25% (2,726 cases) involved foreign objects in food or drink, and 14% (387 cases) of these involved illness or injury associated with foreign objects ingested in beverages or food.  Most of the injuries involved cuts or abrasions in the mouth and throat, damage to teeth or dental prostheses, or gastrointestinal distress.  The foreign objects were rank ordered from most to least common, as follows:  glass, slime or scum, metal, plastic, stones / rocks, crystals / capsules, shells / pits, wood, and paper.  Foreign-object complaints involving injury and illness were associated most often with soft drinks, baby foods, bakery products, cocoa / chocolate products, fruits, cereals, vegetables, and seafood.  For travelers, injury from hard foreign objects can cause a lot of problems if the injury is sufficiently serious to require the attention of a doctor or dentist.
            The Federal Food, Drug and Cosmetic Act (FD&C Act) does not mention the hazards of such items as metal shavings, bits of glass, or metal bolts in food.  "When such items happen to be found in food or drink by regulatory officials, each incident is evaluated and if deemed actionable under the FD&C Act, it is because the foreign object rendered the food unfit [FD&C Act 404(a) (3)] for human consumption due to the offensive mouthfeel of the adulterated food, or has rendered it injurious to health [FD&C Act 404(a) (4)]," (71).
            Functional hazards occur when particle size deviates from that normally produced or supplied, when there are packaging defects (e.g., improper seals or holes in packaging materials), and when food is sabotaged by employees or consumers.  These hazards can be controlled by careful inspection and surveillance techniques by both the supplier of food and the consumer.
            Choking or food asphyxiation hazards include hot dogs, gum drops, nuts, taco chips, steak, or any food that is not chewed sufficiently to be swallowed and hence, becomes lodged in the pharynx, blocking the opening to the esophagus and larynx (11, 78).  Even grapes given to very young infants or children have caused a number of fatalities.  People must chew food adequately before swallowing.
            Old age, poor dentition, and alcohol consumption also contribute to fatal food asphyxiation or choking on food (129).  People should not give large pieces of food to children and the elderly, or to any individuals who are incapable of chewing the food before it is swallowed.  It is also beneficial to be trained to perform the Heimlich maneuver and Cardio Pulmonary Resuscitation, and to travel with other individuals who are trained in these procedures.
            Thermal hazards include serving foods so hot that, when consumed or are spilled on people, can cause severe burns or tissue injury.  When hot foods are served, people must be warned to handle them properly, or foods should be served at temperatures that will not cause injury or harm.  Examples of food causing injury to consumers include:  pizza; cream soups, chocolate, and coffee served at 170°F (76.7°C) or above; jelly Bismarcks over-heated in a microwave; and baby food or baby formula over-heated in a microwave oven to temperatures exceeding 120°F (48.9°C).

    Biological Hazards
            Microorganisms and toxins.  These hazards include pathogenic bacteria, yeasts and molds, viruses, and parasites.  Bacteria can have two basic forms:  vegetative cells and spores.  The vegetative stage is the growing form and stage.  They are sensitive to kill at temperatures as low as 130ºF (54.4ºC).  Vegetative cells are controlled by thermal pasteurization or by double washing.  In the spore state, the Bacillus and Clostridia can dry up, hibernate, and become very resistant to kill.  Sterilization is used as the control, and the common process time is 250ºF (121.1ºC) for 3 minutes.  Some pathogenic bacteria (e.g., salmonellae, shigellae) cause illness due to their proliferation in the intestinal tract of the human body after consumption in food.  Other pathogenic bacteria (e.g., S. aureus, C. botulinum) cause illness when food containing toxins produced by the multiplication of these pathogens in the food is ingested.
            Most yeasts are non-pathogenic, with the exception of Candida albicans (a cause of thrush in infants, elderly people, and other individuals with a compromised immune system).  Some molds produce compounds in food that cause allergic reactions in some people.  Growth of the mold, Aspergillus flavus, in grain produces deadly aflatoxins.  Viruses (e.g., hepatitis A virus and Norwalk virus) may be transmitted through food and water, and in the case of Norwalk virus, air.   Parasites (Giardia lamblia, Cryptosporidium spp., Toxoplasma gondii, and Trichinella spiralis) are transmitted through food and water and are causes of foodborne illness and disease in the United States and other parts of the world.
            Fish and shellfish as sources of toxic compounds.  Fish and shellfish products may contain some of the most potent toxins known.  These toxins are unaffected by cooking, and no antidotes or antitoxins exist to reduce the toxicity of some of these toxins.  Poisonings through eating toxic fish and shellfish are significant causes of human illness.  Outbreaks are usually due to three types of poisoning:  histamine poisoning, paralytic shellfish poisoning, and ciguatera poisoning.  The best controls are to obtain fish and shellfish certified by a supplier with a HACCP program to have been taken from safe waters, and then to store these products under conditions that do not allow deterioration.
            Pests.  Birds, insects, and rodents are a nuisance as well as potential carriers of disease and illness.  In areas without adequate sewage control, flies can be a major source of Shigella contamination.  Pests must be controlled in any facility through cleanliness, both inside and outside.  Debris should never be allowed to accumulate and provide a nesting and/or breeding area for pests.  Facilities must have screens and tight-fitting doors and windows to prevent their entry.  There should be a documented pest control program.
            It is important to realize that pathogens from pests are a very remote hazard in the retail system.  The problem of pest contamination of food usually occurs during growing and harvesting.  Consequently, the retail system must provide control.  Controls include washing the raw fruits and vegetables to remove pathogenic microorganisms, chemicals, and filth, and cooking raw meat and poultry to temperatures that are adequate to destroy pathogenic microorganisms.

    Potential Pathogens in Food
            Since there are many different pathogens of concern relating to pasteurized retail food, what is a simple approach to microbiological hazard control?
            Table 3-2 separates the most important pathogens in various food groups into infective organisms (vegetative cells), which can be controlled by pasteurization, using heat, acid, washing, fermentation, ionizing radiation, etc., to safe levels as defined by Snyder (169).  The safe levels for infective organisms are 10 CFU per gram to 1 CFU per 25 grams.  Toxins and spore-producing microorganisms are not controlled by pasteurization.  The food must be handled so that toxins are not produced, and spores, if they germinate and multiply after cooking, do not increase to an unsafe level.

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