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Lecture 16

HNSC 1200 Lecture 16: Unit 3.4

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Human Nutritional Sciences
HNSC 1200
Snehil Dua

Non-Bacterial Food Contamination Learning Objectives: Discuss the non-bacterial sources of food contamination Course Notes: 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 (PrP). 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 variant form. 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 changes. 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 SRM are: 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 materials used. This is due to the potential migration of chemicals from packaging materials to foods 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 glasses). 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
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