SECTION 3: Hazards in
the Food System
Overview of the Hazards
Potential Pathogens in
Overview of the
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.
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.
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
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.
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.
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
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.
such as copper or lead from pipes or soldering material can leach into
food and water to cause heavy metal poisoning.
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
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
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
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.
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.
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.
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
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).
Microorganisms and toxins.
These hazards include pathogenic bacteria, yeasts and molds,
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.,
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,
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.
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.
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.
to Section 2 (part
to Section 4
to Table of