Lecture 8: Foodborne Hazards and Human Health
• There are two major forms of foodborne illnesses.
• Transmissible diseases
-examples: bacteria, viruses, and parasites (worms, etc.).
• Non transmissible diseases
-examples: Shellfish-associated toxins (something that can cause poisoning), Colour
additives, Bioengineered foods, Obesity, Diabetes.
• Cardiovascular diseases can also be associated with food.
TRANSMISSIBLE FOODBORNE ILLNESSES
Types of Food
• Canada has one of the safest food supplies in the world. However, every year significant
number of people get sick as a result of the contaminated food.
• Some examples of food that could turn out to be the reason of poisoning include: Meat
(number one cause), milk, dairy products (cheese, in summer ice cream can be very risky
from some sources), unpasteurised fruit and vegetable juices (pasteurised fruits and food
material is not that bad for our health, as most the bacteria and contaminants are killed during
pasteurization. But, unpasteurized material can be very toxic if they are contaminated), raw
or undercooked eggs, chicken, tuna, potato and macaroni salads, cream filled pastries, fresh
produce (like some vegetables, spinach can cause food poisoning or salmonellosis), spices,
chocolate (has milk in it), seafood.
• It is not only up to the type of the food, it is also up to how we handle and process the food.
For example, food standing too long in the room temperature (maybe it needs to be in the
refrigerator right away), improper cooking, contaminated cutting boards and kitchen tools.
Symptoms of Foodborne illness
• All of these symptoms are related with your stomach. These include diarrhoea, abdominal
cramping, fever, vomiting, headache, sometimes blood in the stool.
• It could also be that you could have all of these symptoms together. Usually these symptoms
occur after one or two hours of consuming the contaminated food. However, sometimes when
viruses or parasites are the cause of the contamination, then it can happen after a couple of
days or couple of weeks, but not right away. If bacteria are the cause, these symptoms will
start very quickly after you eat the contaminated food.
• Your symptoms will not last for very long, usually no longer then a week. In more severe
cases, the duration can be longer for 7 – 10 days.
• For most people, these diseases are not life threatening if the person does not face the
• They can be very severe for young children as they can de-hydrate very quickly, they cannot
drink as they vomit all the time
• They also can be dangerous for old people as they already have weak immunity. Also they
can be dangerous for people with certain diseases and conditions such as liver disease, iron
disorder (people with lower iron in blood can cause problems if it lasts for a long time),
diabetes, and cancer.
Prevention of Foodborne illnesses
• Prevention of food borne illness starts with your trip to the supermarket. • In the supermarket: Pick up your packaged and canned foods first, don't buy food
in cans that are bulging or dented or in jars that are cracked or have loose or bulging lids,
check the expiration date, avoid seafood (if you have weak immune system), choose eggs that
aren’t cracked and refrigerated in the store. Select frozen foods and perishables such as meat,
poultry or fish last to avoid melting, and put in separate bag so that drippings don't
contaminate other foods
• In the home: properly store your food. You have to keep certain foods in
refrigerator and some food frozen. Meats can last about 2 – 3 days in a fridge, but after that it
has to be frozen. Basically keep food in safe place.
• Food preparation: Never cut meat (first processing meat) on a cutting board, and
then use the same board for cutting vegetables without washing the cutting board. A good
solution to wash the cutting board is bleach. Basically, 5 millilitres of bleach for one hour in
water. To sum this all up, you need to keep everything clean. You must wash hour hands
before you touch food or anything food related. Keep hot food hot and cold food cold.
• Cook food properly: raw food can cause food borne illnesses. This is because
inside raw meat you do not kill bacteria.
• You must properly store leftovers: leftovers must be closely packed and placed in
the fridge. It is supposed to be consumed in the next 3 days. Brushes, sponges or cloths used
in the kitchen can be source of contamination as well. Always disinfect them with bleach, or
simply buy new ones.
Bacteria: Escherichia coli
• It can cause contamination in water. Food poisoning usually associated with eating unwashed
vegetables and meat contaminated post-slaughter (contaminated in kitchen boards, after you
buy the meat).
• The biggest source of contamination is grounded beef.
• Common symptoms include diarrhoea, vomiting, abdominal (stomach) cramps. Basically,
these are common symptoms for any food borne disease.
• Face complications such as Hemolytic Uremic Syndrome (where the red blood cells are
destroyed). This means that the immune system is destroyed as the red blood cells are part of
our immune system. As a result of that, kidneys fail. It will lead to death if we are not treated
• Around 2% – 7% of all cases will have these complications.
• It is very similar to Escherichia coli, as the symptoms are very similar.
• Only medical doctors can realize what is really happening, by analyzing the stool and
detecting what kind of bacteria caused this illness.
• Closely associated with animals. That is, it is related to feces of certain types of animals.
When food comes in contact with animal feces, it might result in salmonellosis.
• Small turtles are common source of the illness.
• Often we get warnings to not to eat certain types of spinach or some other leafy vegetable.
However, spinach is more common as it gets contaminated somewhere between growing and
our kitchen table.
• There is usually no need for treatment. It will last 2-3 days with its symptoms and finished.
No medication is necessary.
Bacteria: Botulism • Food borne illness that is very rare but very serious and fatal.
• In US, every year there are only five or ten cases.
• It is caused by nerve toxin produced by bacterium called Clostridium botulinum. This
bacterium does not cause illness by itself, only toxin causes the problem
• Associated with home- canned foods (not commercially canned foods).
• Commercially canned food has to go through certain process that is called “botulinum cook".
Each can is cooked at 121 °C (250 °F) for 3 minutes. This means that Clostridium botulinum
bacteria and their spores will be killed.
• Usually home-canned food are not pasteurized long enough or maybe not treated under
• Some unusual sources
1) Garlic or herbs stored covered in oil.
2) Improperly handled baked potatoes wrapped in aluminium foil.
3) Home-canned or fermented fish
Main Kinds of Botulism
There are three major kinds of botulism.
1. Food borne botulism – when the food already contaminated with toxin (produced by
Clostridium Botulinum) is consumed
2. Wound Botulism - contamination of wound by the bacteria, it has similar symptoms but
entrance is different
3. Infant Botulism - very rare, when kids can consume spores of Clostridium botulinum, not the
toxin, and then in their body that bacterium produces toxins. Consumed (accidentally) in some
dirt or sand