Week 9 Flashcards
(42 cards)
direct links between food, environment, and health
- quality (nutrition)
- quantity (calories)
- food borne illness
indirect links between food, environment, and health
- antibiotic resistance
- pesticide residues
environmental impacts (that lead to health impacts):
- climate change
- energy use
- land use
- water use
overnutriton and undernutrion stats
almost 1 billion people are hungry
almost 2 billion people are eating too much of the wrong food
3 hazards for food borne illness?
- biological hazard
- bacterial, viral, parasitic
- 97% of all reported outbreaks are due to microbial source
- bacteria are the leading cause of illness - chemical hazards
- naturally occurring: plant or fish toxins
- man-made: pesticides - physical hazard
- bone fragments, pieces of glass, etc.
risk factors for food borne disease outbreaks
- improperly refrigerated food
- improperly heated or cooked foods
- food handlers who practice poor hygiene
- lag between preparing and serving food
- introduction of raw or contaminated materials into a food that will not undergo further cooking
- cross-contamination with raw foods, contaminated utensils, or machinery
food borne illness - salmonellosis
- caused by bacteria in the salmonella genus
- liv in the intestinal tracts of humans and animals (especially birds)
- often associated with poultry, meat, eggs
- consumption of contaminated foods
- foods can become contaminated with fecal material from unwashed hands
- diarrhoea, abdominal pain, vomiting
- higher mortality rate (3%) among very young, elderly
food borne illness - E. coli
- Found in healthy cattle intestines; spread through feces
- Common sources: undercooked beef, unpasteurized milk
- Very low infective dose (Even a tiny amount of E. coli can make someone very sick)
Symptoms:
- Bloody diarrhea (hemorrhagic colitis)
- HUS (Hemolytic Uremic Syndrome): red blood cell destruction, kidney clots/failure
- Leading cause of kidney failure in children
food borne illness - listeriosis
- bacterium listeria monocytogenes found in soil and water
- associated with milk, soft cheeses, meats, and vegetables
- relatively rare but high fatality rate (20-30%)
- mild symptoms in healthy individuals: fever, muscle aches, sometimes GI symptoms
- susceptible groups: pregnant women and foetuses, very young, elderly, immunocompromised
- pregnant women: miscarriage, premature delivery
- capable of slow growth at low temperatures (in fridge too)
2008 outbreak from Listeria - how many deaths and the outcome?
outbreak from Listeria-contaminated lunch meats produced by Maple Leaf Foods lead to 23 deaths in Canada
- many lived in long-term care facilities
food borne illness - prevention (HACCP) 7 steps
Hazard Analysis Critical Control Point (HACCP) Food Safety System:
1. conduct a hazard analysis
2. determine critical control points
3. establish critical limits
4. establish a system to monitor the CCPs
5. establish corrective action for when a CCP is not under control
6. verify that the HAACP system is working
7. establish good record-keeping
Water
- providing an adequate supply (quantity) of drinking water free from biological and chemical contamination (quality)
- UN and WHO: “improved drinking water” sources defined as: sources that by nature of their construction or through active intervention, are protected from outside contamination, particularly fecal matter
sanitation
- providing adequate treatment and disposal of human waste (sewage)
- “improved sanitation” facilities defined as: facilities that ensure hygienic separation of human excreta from human contact
Water and Health - indirect links
- drought
- flood
- vector borne disease (e.g., malaria)
- war/conflict?
water and health - direct links
- disease / illness
- biological (water borne illnesses)
- chemical (e.g., arsenic, lead, industrial chemicals)
Types of water the earth supplies
- 97% of earths water is saltwater
- 2/3 of freshwater is ice in arctic, antarctic
- free freshwater <1% of world water (this is the supply that is available for drinking, agriculture, etc.)
two main water supplies
Surface water
- all water naturally open to the atmosphere, e.g., rivers, lakes, etc.
- traditionally considered less desirable for drinking water
Ground water
- supply of freshwater found beneath the earths surface, usually in aquifers, which supplies wells and springs
- traditionally considered more desirable for drinking water
Mortality in the US fell dramatically from 1900-1940 due to what?
Clean water responsible for a large portion of this mortality reduction in major cities:
- 50% in adults
- 65% in children
- 75% in infants
May 2000, Walkerton’s water supply contaminated with E. coli - how many died and what contributed to this?
contaminated by manure spread at a farm near a well
- heavy rain also contributed
7 died and 2,300+ became ill (out of a pop of 5,000)
Cause:
- could have been prevented by the use of continuous chlorine residual and turbidity monitors at the well
- Walkerton utilities manager Stan Koebel was sentenced to 1 year in jail for operating a well w/out a chlorinator, failing to properly monitor and test the well water, forging records
1993 Cryptosporidium outbreak in Milwaukee
- cryptosporidium in untreated water from Lake Michigan apparently entered the southern water-treatment plant and were then inadequately removed by the coagulation and filtration process
- over 400,000 people affected including 1/2 of those whose water came from the southern treatment plant
- 54 deaths
- 4,000 hospitalisations
Chlorine disinfection byproducts
- chloroform - IARC Group 2B
- bromodichloromethane - IARC Group 2B
- Dibromochloromethane - IARC Group 3
- Bromoform - IARC Group 3
Chlorine - disinfectant for water
benefits: retains a residual and strong disinfectant
- The chlorine residual continues to kill or inhibit bacteria as the water moves through pipes or is stored - the protective barrier
Concerns: taste and odour; toxicity of by-products; some microbes are resistant; not effective at a high pH
Cost: Moderate
How do we know if water is free of pathogens? The Indicator Approach
Coliforms:
What does it indicate - presence of the coliform group of bacteria, many of which are present in human or animal fecal material
Limitations - certain coliform grow naturally in drinking-water biofilms, particularly at warmer temperatures. Not indicative of protozoa or viruses
Water contamination: metal - arsenic
- ubiquitous, naturally occurring element
- organic and inorganic forms (inorganic form (from natural sources) in drinking water greatest source of human exposure)
- acute poisoning - generally a little concern outside of select occupations
- chronic exposure - skin lesions (earliest effect), damage to liver, vascular disease (atherosclerosis), cancer (skin, lung, and bladder) - IARC Group 1
What is waste water?
Used water typically from industry, households, etc.
- wastewater can negatively affect the environment and human health if not properly transported and treated
