Environmental Hazards and Risks

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 injury, disease, or death to humans damage to personal or public property deterioration or destruction of environmental components

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A. Lack of familiarity with technology
B. Extent to which the risk is voluntary
C. Public impression of hazards
D. Overselling of safety
E. Morality
F. Control
G. Fairness

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Cultural
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Chemical
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Physical
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Biological

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Natural disasters
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Fires
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Ionizing radiation
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Electromagnetic radiation (UV rays, X-rays, gamma radiation, etc) which has enough energy to knock electrons from molecules and cause damage to cells.
Can damage reproductive or somatic cells

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Transmissible diseases like yellow fever, flu, dengue fever, tuberculosis, malaria, etc.
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Pathogen - infectious agent
Vector - helps to spread the pathogen (mosquitoes of greatest concern)
Malaria - huge problem in subtropical and tropical areas. The pathogen is a protozoan (Plasmodium) and the vector is the Anopheles mosquito.
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Drug resistant bacteria are becoming more prevalent due to overuse and misuse of antibacterial products
Non-transmissible diseases
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Cardiovascular disease, cancer, diabetes, emphysema, etc.

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Cultural
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Poverty - according to WHO this is the biggest killer
Smoking
Unsafe sex
Diet - people in developed nations are more likely to die from cardiovascular related diseases

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Mutagens
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Teratogens
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Carcinogens

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Consist of hundreds of highly persistent chemicals.
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Some of the most toxic substances known.
The worst is TCDD.
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No safe level of exposure.
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These are biproducts of industrial processes that use chlorine like paper bleaching, the production of PVC plastic, and pesticides.
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Primary toxic component of Agent Orange and found at the site of Love Canal.

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Carcinogenic
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Causes reproductive problems: increases likelihood of miscarriage, decreases fertility, and sperm counts
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Also linked to diabetes, skin disorders, immune deficiencies, and learning disabilities

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Fat-soluble; bioaccumulates in living organisms
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93% of exposure is through meat and dairy products
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It is hydrophobic and lipophilic (which means when it gets into water, it will rapidly accumulate in fish bodies)
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In women, dioxins can cross the placenta and it is present in breast milk

Viktor Yushchenko Does freezing water release dioxins?
Major source of release is incineration How about microwaving plastics?

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No longer produced in U.S.
Highly prized for flame resistance and used in many electrical products b/c they didn’t burn or react with other chemicals
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Found in such varied items as heating coils, carbonless carbon paper, power saws, cereal boxes,varnishes, and bread wrappers.

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Persistent
Bioaccumulate in fat; biomagnify through food chain
Highly toxic: can be ingested, inhaled, or absorbed through the skin
Health effects: chloracne, damage to liver, damage to nervous system, damage to reproductive system, and may affect immune system
Can be exposed by contact with old appliances, old flourescent lighting fixtures, food or water intake, or in some jobs

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Often associated with exposure to pesticides:
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These suppress the body’s natural defensive mechanisms and make the body more vulnerable to disease.

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Called neurotoxins and affect the brain, spinal cord and peripheral nerves
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Include DDT, PCBs, dioxins, organophosphate pesticides, formaldehyde, compounds containing heavy metals (As, Hg, Pb, and
Cd), and industrial solvents like trichloroethylene (TCE), toluene, and xylene.

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Affect the body’s hormones.
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Each hormone has a specific molecular shape which allows it to bind to only specific cell receptors, but some chemicals may act as hormone mimics or blockers and fool the cells by either binding to them or blocking them from the proper hormone

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Ranch minks
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Lake Apopka alligators
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Rats exposed to PCBs
 p-nonylphenol
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Florida panthers

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Toxicity - the measure of how harmful a substance is.
Dose - amount of potentially hazardous substance that has entered the individual. The amount of harm will depend on the size of the dose over time.
 a. Acute exposure - single dose.
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 b. Chronic exposure - doses over most of a lifetime.
c. Subchronic exposure - repeated doses for some fraction of a lifetime.
“The dose makes the poison.”

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Response - type and amount of damage as a result of exposure.
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 a. Acute effect - immediate or rapid harmful reaction.
b. Chronic effect - permanent or longlasting consequence from exposure.
c. Multiple chemical sensitivity - an individual becomes sensitive to many chemicals at the same time.

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Case reports
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Laboratory investigations
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Epidemiology (involves the study of various human populations which have had exposure to the chemical)

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Lethal Dose 50% is the amount of one dose of a chemical that can kill 50% of the animals in a test population in a 14 day period.
A poison is a chemical with an LD weight.
50 of 50 milligrams or less per 1 kilogram of body

-is developed with acute toxicity tests.
These are done as controlled experiments. Some of these curves have threshold levels, while others do not.
-a threshold level implies, that there must be some minimal level of exposure before any effects are seen.

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Water soluble
Fat soluble

 an increase in the concentration of a chemical in specific organs or tissues at levels higher than normally expected.
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The residence time of a chemical is given by its biological half-life (the time needed for the quantity of the chemical in the body to be reduced by half).

 a magnification of the levels of some toxins in the environment as the pass through food chains/webs.
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Examples: PCB’s. DDT, radioactive isotopes ii.
Passed to offspring through gestation and nursing