Lecture 9 Flashcards
1
Q
What are environmental hazards?
A
- these have a wide and varied interpretation
- they can vary from a single toxic chemical accident to an entire industry (eg. nuclear energy)
- other examples may include exposure to pollutants or hazardous waste
- hybrid disasters may fit into this category (ex: an earthquake that causes an oil or chemical spill from a pipeline)
- technological disasters involving the environment are included in this category as well (ex: sinking of the Titanic, explosions of the Challenger and Columbia space shuttles)
2
Q
Who is most vulnerable to environmental hazards?
A
- typically the death tolls from environmental hazards are relatively low
- vulnerability is greatest for those involved in industry or transportation systems
- workers in resource industries in hinterlands are at higher risk (eg. miners)
3
Q
What are categories of environmental hazards?
A
Widespread: long term (nuclear accidents), hazards leading to cumulative effects
Rare Events: airplane crashes, mine collapses, shipwrekcs
Common: automobile accidents, poisons
4
Q
What are cumulative effects?
A
- conditions that worsen slowly over time as exposure to a concentration increases
- eventually, the concentration reaches a threshold critical to human health
- situations related to this include exposure to toxic chemicals, acid precipitation, groundwater contamination, and ozone depletion
5
Q
How is risk calculated for large-scale structures, transportation, and industry
A
Large-scale structures (buildings, bridges, dams): risk is defined as the probability of failure during the lifetime of the structure
Transportation (road, sea, rail): risk is the probability of death or injury per km travelled
Industry (manufacturing, power production): risk is the probability of death or injury per person per number of hours exposed
6
Q
What is radon?
A
- the primary source of radon gas is from the natural decay of uranium in rock and soil
- when radon is inhaled it then decays to polonium and lodges in the lungs where it damages tissues
- it is the 2nd leading cause of lung cancer in NA
- radon becomes a hazard when it is released into our living space
- it is difficult to detect because the gas is odourless, colourless, and tasteless
- potentially high radon levels are present in 5-10% of homes in NA
- radon detectors are commerically available in areas where it is of greater concern
- the gas can move quickly through non-saturated soil and can seep into homes
- basements are at higher risk especially in winter due to reduced air circulation
7
Q
What are genetically modified organisms?
A
- these are organisms that have had changes made to their DNA by the transfer of genes
- example feats in genetic engineering: chickens that lay low-cholesterol eggs, tomatoes that can prevent some cancers, bananas and potatoes to treat viral diseases in developing countries, rice that can produce more vitamin A
- bacteria that can quickly clean up oil and toxic spills
8
Q
What are genetically modified foods?
A
- the most common crops that are genetically modified are corn, soybean, and canola
- crops are modified to increase yields
- some crops have been genetically engineered to have greater resistance to changes in temperature and precipitation, herbicides, pests, and acidic soil
- bioengineers have been able to alter citrus trees (that would normally take 6 years to produce fruit) to yield fruit in only one year
- how safe are genetically modified foods? scientists believe that the benefits outweigh the potential risks but most support more reserach studies
- the UN food and agriculture organization believes that genetically modified crops have great benefits for developing countries
9
Q
Describe radiation
A
- the pathways of radiation include inhalation and ingestion (food,water)
- the impact can be direct (effects are evident within days of exposure) or delayed and chronic (leukemia, cancer)
- the impact could also be indirect in the form of genetic effects
- a person may not experience effects but may pass them on to their children in the form of chromosomal changes or birth defects
10
Q
What are sources of radiation?
A
- mining of uranium: in Canada, uranium is mined in northern Saskatchewan and northern Ontario, mines produce wastes known as tailings that can be a radioactive hazard
- production of electricity: uranium is used in nuclear power plants
11
Q
Where are nuclear power plants located?
A
- most nuclear plants in North America are located in the eastern half of the continent
- they must be near sources of coolant (rivers or lakes)
- they must be located near a market for electricity (eastern NA is much more populated)
- nuclear is considered a clean source of energy because it does not emit the greenhouse gases that cause climate change
12
Q
What is a nuclear meltdown?
A
- informal term for an accident that results in damage from overheating
- it occurs when the heat generated by a nuclear plant exceeds heat removed by cooling systems
- in a meltdown, fuel rods turn to liquid and the walls of the plant core could melt from extreme heat
- the hot liquid could melt through the bottom of the power plant and seep into the soil
13
Q
Describe the Three Mile Island nuclear accident
A
- this is the worst nuclear disaster in US history; it occurred on March 28 1979
- one of the two power plants on three mile island in central pennsylvania experienced a partial meltdown
- it was caused by a failure of a valve that controlled cool water entering the plant core
- there were no direct injuries; minor amounts of radiation were released around the site
14
Q
Describe the Chernobyl nuclear accident
A
- worst nuclear disaster in world history; it occurred on April 26 1986
- the accident was a result of a flawed design, operator error, and disregard of safety regulations
- an explosion at the plant caused the immediate deaths of 3 workers
- within one year 28 more workers died from extreme radiation exposure
- an estimated 6000 people in the area developed thyroid cancer as a result of radiation poisoning
15
Q
How did the concern over nuclear meltdown impact nuclear energy?
A
- halted nuclear development for a time
- however, concern over greenhouse gas emissions has created a greater demand for cleaner sources of energy
- for example, Ontario has recently closed all of its coal power plants
- to meet this objective the province is investing in refurbishing existing nuclear power platns and is planning to build new nuclear plants as well
16
Q
Describe the Titanic Shipwreck
A
- The Titanic was a passenger ocean liner that struck an iceberg and sank on its maiden voyage (April 15 1912)
- the ship left Southampton, England on April 10th and was bound for New York City with 2224 passengers
- ship was designed using advanced technology and was believed to be unsinkable
- the death toll was 1517; the high number was due to the lack of lifeboats for all passengers
- the wreckage was found by SONAR in 1985 at a depth of 3.8km
- a lookout on the ship spotted an iceberg in the ship’s path at 11:40pm and alerted the captain
- the ship struck the iceberg 37 seconds later; 18 lifeboats were launched and Titanic sank at 2:20am
- the Carpathia arrived at 4:10am and picked up survivors from the lifeboats
30
Q
Describe cholera and early mapping of cholera
A
- it is a water-borne disease that originates in sewage and contaminated streams within an urgan or rural water supply
- it is caused by infection of the intestine by a bacterium
- this disease is extremely rare in developed countries
- it is still common today in parts of rural India and sub-Saharan Africa
- when cholera emerged in London, England in 1854 the source was unknown
- at this time it was not known that cholera was spread by drinking contaminated water
- each reported case of cholera was mapped and the source was then traced to a specific water source
- this is the first example of using mapping to identify the source and spread of a disease
31
Q
Describe HIV/AIDS
A
- the Human Immunodeficiency virus (HIV) leads to AIDS (acquired immune deficiency syndrome)
- it first surfaced in 1980 and became a major pandemic of the 20th century
- it is transferred through exchange of bodily fluids
- it was originally believed the disease was limited to homosexual activity and intravenous drug use
- when the disease first surfaced it was somewhat ignored because it was not affecting the mainstream population
- it has claimed over 30 million lives
- estimated that 40 million people are currently infected
- most current cases (95%) are found in developing countries
- there is no cure, but antiretroviral drugs are extending life thus turning it into a chronic disease
35
Q
Describe the bird flu
A
- it is also referred to as avian flu
- it first became evident in 1997 in Hong Kong where there was a large death of poultry with 100% mortality
- it was combatted by the killing of all poultry but another outbreak occurred in 2003
- the focus is on the virus strain H5N1 because it is able to transfer from birds to humans, there is high mortality in humans, it has the potential to produce a severe pandemic
- the disease is caused by a virus that occurs naturally among birds
- spread of H5N1 virus from person to person is rare and presently the spread has not continued beyond one person
- humans infected have been those who work daily in close contact with poultry
- of people who become infected, 70% die from the virus
