Non-Bacterial Food Contamination
Discuss the non-bacterial sources of food contamination
1. Bovine Spongiform encephalopathy (BSE): Mad cow disease
As of 2008, there have been a dozen cases of BSE reported. BSE is an example
of a transmissible spongiform encephalopathy (TSE).
Transmissible spongiform encephalopathies (TSEs), are diseases that cause
brain of the victim to become riddled with holes, taking on sponge-like
(Swiss cheese) consistency.
The cause of TSEs in animals and humans is a small protein known as a prion
A prion is an infectious protein particle that does not contain DNA or RNA.
The prion can occur in two forms; normal conformer (PrPc, causes no
problems in the body), and rogue conformer (PrPsc, causes problems).
The PrPsc causes the normal PrPc to change shape, causing destruction
of cells as the prion travels through the spinal cord to the brain and
causes damage (holes) in the brain.
Creutzfeldt-Jacob Disease (CJD) is a TSE that causes dementia in humans.
Most cases effect those over 65 years of age and all cases result in death
within 1-10 years.
SJD incidence in the United Kingdom was low prior to 1995, at which point a
new variant of CJD (nvCJD) emerged.
This new form of CJD began affecting teenagers and young adults.
The cause is unknown, however some scientists have linked nvCJD to
the consumption of cattle infected with bovine spongiform
encephalopathy (BSE), specifically spinal cord or brain material.
Note that CJD itself is not linked to consumption of BSE cattle, only the new
BSE is known as “mad cow disease”. It is a degenerative disease in cattle that
affects their central nervous system cSD
Symptoms include convulsions, loss of coordination and behavioural
BSE was first seen in cattle in Great Britain in 1985 and was traced to
feeding cattle bone meal from dead, diseased sheep suspected to have been
stiffening from Scrapie (a TSE seen in sheep that causes loss of coordination
and intense itching of the animal).
Because of this, Great Britain banned animal-based feed supplementsfor
animals in 1989.
Canada also implemented this same ban in 1997
Health Canada has taken many steps to reduce the risk of Canadians
becoming infected by BSE, such as removing specified risk materials
(SRM) fro all cattle produced in Canada after they are slaughtered.
SRM are the parts of cattle that are most likely to contain BSE, so these are
removed so that they do not end up in the food supply
The skull, brain, trigeminal ganglia (nerves attached of the brain),
eyes, tonsils, spinal cord and dorsal root ganglia (nerves attached to
the spinal cord) or cattle aged 30 months or older
The distal ileum of cattle of all ages
Scientific research has shown that BSE does not transfer to the muscle meat
of cattle so steaks and roasts would not be affected and Health Canada and
the World Health Organization consider this meat safe.
2. Food packaging Materials
In today’s marketplace there are a variety of different types of food packages
used, with a trend towards packages that the food can be cooked inside (e.g.,
microwave popcorn, steam bags for vegetables).
It is important to realize that not all food packages can be used in the
microwave with your food
Unless the package says it is microwave safe, there is a risk that the heat can
cause the plastic to melt in the food, and the risk that chemicals can migrate
out of the plastic into the food product.
The food manufacture/seller bears a legal responsibility for safety packaging
This is due to the potential migration of chemicals from packaging materials
Manufacturers must submit data on:
o Chemical composition of material
o Intended end use
o Extractability of chemicals in packaging materials by food
o Toxicological data on residues OSDP
Bisphenol A (BPA)
Specific regulations exist for some packaging materials with limits set on
levels permitted and migration limits
There has been a lot of media attention on Bisphenol A (BPA), which is a
chemical used in the production of hard, clear plastic called polycarbonate.
Polycarbonate is used in a variety of food contained (e.g., reusable water
bottles, infant bottles, food storage containers, outdoor table wear and
BPA is also used in the production of epoxy resins, which are used to line the
inside of food and beverage cans
Small amounts of BPA may leach out into the food or water stored in these
containers, however this exposure is of no risk to Canadians, with the
exception of newborns and infants, where the level of exposure can reach
that seen in animal studies to cause adverse health effects.
The effects seen in animal research have shown that BPA can have estrogen-like
activity in the body and may be an endocrine-disrupting agent
The recommendations that Health Canada gives to parents are:
Do not put boiling or very hot water into polycarbonate baby bottles
(as this can cause BPA to leach at a higher rate). Allow boiled water
or liquids to cool to lukewarm before placing in the baby bottle
Allow polycarbonate bottles to cool to room temperatur