Week 9 Flashcards
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
Wastewater Treatment Systems
- the aim of sewage treatment is to improve the quality of wastewater to the point that it can be discharged into a waterway without seriously disrupting the aquatic environment or causing human health problems
- one-site systems: septic tanks, drain fields
- municipal systems: primary (screening, settling), secondary (biological process for digestion of solid organic wastes), tertiary/advanced secondary (additional chemical, biological treatment)
GBD - water, sanitation, and hand washing behaviour
- responsible for 1.6 million deaths annually (most in sub-saharan Africa and India)
- second leading contributor to disease burden in sub-saharan Africa
- responsible for > 90% of diarrhoea disease and > 10% of lower respiratory infections globally
- disproportionately affects young children
Hand hygiene stats
- 2.3 billion people lack a facility with water and soap available to wash their hands at home
- 670 million have no handwashing facility at all
- 460 million children attend school with no hygiene facilities
- slow increase in access
Millennium Development Goals (MDGs) - drinking water
- the MDG for drinking water was met 5 years ahead of schedule
- from 1990 to 2015 the portion of the global population with access to an improved drinking water source increased from 76% to 91%
- 2.6 billion people gained access to an improved drinking water source
- still ~600 million people using unimproved drinking water sources
Millennium Development Goals (MDGs) - sanitation
- MDG for sanitation was not met
- from 1990 to 2015 the proportion of the global population using an improved sanitation facility has increased from 54% to 68%
- 2.1 billion people gained access to improved sanitation
- the proportion of people practicing open defecation globally fell almost by half, from 24% to 13%
- still 2.4 billion people using unimproved sanitation facilities, including 900 million people who are still practicing open defecation
Sustainable Development Goal 6
6.1 By 2030, achieve universal and equitable access to safe and affordable drinking water for all
6.2 By 2030, achieve access to adequate and equitable sanitation and hygiene for all and end open defecation
Solid and hazardous wastes
Solid waste typically falls into 1 of 3 categories:
1. Municipal solid waste (non-hazardous)
- everyday waste from homes and businesses: paper products, food waste, plastics, etc.
- generally poses no immediate threat to human health and/or the environment
2. Special Waste
- medical waste
- construction debris
- sewage sludge
3. Hazardous waste
- waste with properties that make it capable of harming human health or the environment
Solid Waste Disposal
- open dumping
- landfills
- incineration
- composting
- recycling
landfills
Potential environmental problems:
- leachate: water passes through waste and accumulates waste products (e.g. metals), can contaminate groundwater
- gases: produced from decomposition process (odors, can be flammable, explosive ex: methane)
Other potential problems:
- decreased property values
- land use conflicts (NIMBY)
Landfill design
- Site considerations
- adequate area
- available soil for coverage requirements
- proximity to surrounding populations - Design
- liner (barrier between landfill and underlying soil and groundwater)
- leachate collection system - Monitoring
- groundwater contamination
- methane gas (in some cases)
incinerators
Most common in locations with major space limitations:
- some is waste-to-energy
- incineration often refers to systems without energy recovery
Goals:
- reduce the volume of waste and/or
- reduce hazardous characteristics of the waste
Concerns:
- air pollution, e.g., combustion of some organics in presence of chlorine can produce dioxins - requires control technology
- ash can contain toxic materials such as some heavy metals
Global Solid Waste Disposal
In canada:
- 95% of waste disposed at waste disposal facilities (not recycled or composted) was at landfills
- remaining 5% of municipal solid waste disposal at incinerators
Solid Waste Disposal in our Region
- waste-to-energy incinerators - south burnaby
- landfills: Vancouver (delta) and cache creek
Health concerns of solid waste
- infectious disease from solid waste (poorly operated landfills –> rats, mosquitoes)
- drinking water contamination (leachate)
- air pollution from landfills
- air pollution from incinerators
hazardous waste
Waste with properties that make it capable of harming human health or the environment
Typically one of the following:
- corrosive (e.g., pH < 2 or > 12)
- flammable
- reactive
- toxic
Examples:
- pesticides, solvents, paints, radioactive materials, acids, etc.
NIMBY
Not in my backyard
- waste must go somewhere
- of all the challenges that contemporary policymakers must confront, few can be more difficult than those that narrowly concentrate costs
waste disposal
the idea is that without regulations on the movement of waste, in a free-market system waste will move to the place where it can be disposed of at the lowest cost, and that will generally be low and middle income countries (often lower wages, weaker environmental regulations, and fewer rules on workplace safety)
e-waste
- computers, televisions, cell phones, etc.
- relatively inexpensive
- technological advancement, obsolecence
- marketing
- 54 million metric tons of e-waste generated worldwide in 2019
- waste contains valuable components including aluminium, copper, and iron
- also contains potentially hazardous components including brominated flame retardants and mercury
- most of e-waste is sent to developing countries (often illegally)
