Transcript Human Health and Environmental Risks

Human Health and
Environmental Risks
Many risk factors
physical
• Natural disasters
• Excessive UV radiation
Biological
• Diseases
chemical
• Natural and synthetic
• Ex: pesticides, arsenic
Diseases
• Acute
– Impair body rapidly
– short in duration
– Ebola, pneumonia
• Chronic
– Slowly impair body over
decades
– Heart disease, cancer,
lung disease, HIV/AIDS
toxicology
• Neurotoxins – EX: insecticides on insects, lead, mercury
• Carcinogens – cause cell damage and cause uncontrolled
growth of these cells EX: asbestos, radon, formaldehyde,
PCBs, vinyl chloride, chemicals in tobacco
• Teratogens – interfere with embryo/fetal development EX:
thalidomide, alcohol
• Allergens – high response of immune system EX: peanuts,
milk, penicillin, mold
• Endocrine disruptors – interfere with hormones EX:
hormones from birth control pills/animal-rearing places in
sewage, low sperm count in male fish and amphibians, DDT
Chronic disease risk factors
• Differ between LDC and HDC. HOW?
• LDC associated with poverty: unsafe drinking water,
poor sanitation, malnutrition
– ½ children under 5 that die from pneumonia is
because of poor nutrition
– ¾ children who die from diarrhea suffer from poor
nutrition
• HDC: tobacco, less active lifestyles, poor nutrition,
overeating
Historically important infectious
diseases
• Plague – bacteria transmitted by fleas
• Malaria – protists transmitted by mosquito;
eradicated in US due to DDT
• Tuberculosis – bacterial infection of lungs;
medicines not available/affordable in LDC
– Drug-resistant strains
Emergent Infectious Diseases
• Ability of many pathogens to mutate and be able to infect
humans
• HIV/AIDS – combination antiviral drugs reduce virus gaining
resistant ($$, but changing)
• Ebola hemorragic fever – virus, central Africa, 50-90% death
rate, no drugs, death in 2 weeks)
• Mad Cow Disease – prions (proteins turned pathogens)
• Bird Flu – not typically transmitted person to person, typically
only infects birds, but mutated
• West Nile Virus – kills some birds, transmitted by mosquitoes,
causes brain inflammation, infect humans and horses
Future?
• LDC : improve nutrition,
wider availability of
clean drinking water,
proper sanitation
• HDC: promotion of
healthier lifestyle:
increased physical
activity, balanced diet,
limit excess food
consumption, and
tobacco use
**All countries: continued education to reduce
spread of HIV and TB
Determining the concentration of a
chemical that is harmful
• LD50 – dose that kills 50% of test subjects
– Unethical on humans; use mice/rats
– Used to compare toxicity of different chemicals
• ED50 - dose that effects 50% of test subjects
challenges
• Kids vs adults
• Synergistic interactions of chemicals – 2 risks
together cause more harm than one would
expect based on their individual risks
– Health impact of a carcinogen, like asbestos, can
be much higher if an individual also smokes
tobacco.
Risk analysis
• Typically 3 steps:
– Risk assessment
• Identify hazard and determine extent of exposure
– Risk acceptance
• Determine acceptable level of risk
– Risk management
• Determine policy (with input from citizens, industry,
interest groups)
Risk analysis put into action…
• Maker of electrical components dumped PCBs into Hudson
River
• PCBs in air, soil, water and persist
• EPA identified at what concentration PCB caused cancer
(LD50/dose-response)
• Greater chance of getting cancer from eating contaminated
fish  put up signs to minimize exposure
Perceived risk vs. actual risk
• Perceived (qualitative) / actual (quantitative)
– Ex: someone afraid to fly in airplane, but will drive
car all the time.
– Death in US:
• 1. heart disease (1 in 5)
• 2. cancer (1 in 7)
• 3. COPD
ECONOMIC IMPACTS OF
POLLUTION
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COST-BENEFIT ANALYSIS
EXTERNALITIES
MARGINAL COSTS
SUSTAINABILITY
• Economic activity generally harms the
environment
– Cost to environment not included in cost to buyer
– External costs (externalities) are harmful social or
environmental effects caused by the production or
consumption of economic goods
• Buy cotton t-shirt at a price that doesn’t reflect possible
eutrophication due to fertilizer run-off or poor working
conditions in “sweat shops.”
• Ex: paper manufacturer dumps wastes into local river
(public goods)  negative impacts on fish that depend
on water, decrease quality of water used for recreation,
extensive treatment of water to drink downstream
Cost-benefit analysis
• Cost-benefit analysis looks at the social benefits
(health/environmental) that can be derived from pollution
reduction vs the cost of achieving that reduction.
– There is a limit to how much money can be spent before the budgets
of other important public services (police, fire, parks departments) are
negatively impacted.
– As hazards become more known, perceived benefits derived from
pollution reduction may increase.
– Problem with analysis: assumes all benefits have a price tag. Aesthetic
benefits cannot be prices and are important (beauty of a clear-running
stream and quiet solitude of a wilderness)
Marginal costs
• The change to the total cost when the quantity
produced changes by one unit.
• Marginal cost of pollution abatement: Initial clean-up of
a polluted site is cheap, but gets increasingly more costly
Sustainability
• Seek to proved best outcomes for both human
societies and natural ecosystems.
– Conservation of biodiversity and ecological integrity
– Integration of environmental, social, and economic
goals in policies and activities
– Need for good governance
• Unlimited economic and population growth puts
many demands on natural resources.