Transcript Risk - TeacherWeb

Environmental Hazards and Risks
the possibility of suffering harm from
a hazard that can cause injury, disease,
or environmental damage
 injury,
disease, or death to humans
 damage to personal or public property
 deterioration or destruction of
environmental components
 A.
 B.
 C.
 D.
 E.
 F.
 G.
Lack of familiarity with technology
Extent to which the risk is voluntary
Public impression of hazards
Overselling of safety
Morality
Control
Fairness
 Cultural
 Chemical
 Physical
 Biological
 Natural
disasters
 Fires
 Ionizing


radiation
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
 Transmissible
diseases like yellow fever, flu,
dengue fever, tuberculosis, malaria, etc.
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.
 Drug resistant bacteria are becoming more prevalent
due to overuse and misuse of antibacterial products


 Non-transmissible

diseases
Cardiovascular disease, cancer, diabetes, emphysema,
etc.
 Cultural




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
 Mutagens
 Teratogens
 Carcinogens
 Consist
of hundreds of highly persistent
chemicals.
 Some of the most toxic substances known.
The worst is TCDD.
 No safe level of exposure.
 These are biproducts of industrial
processes that use chlorine like paper
bleaching, the production of PVC plastic,
and pesticides.
 Primary toxic component of Agent Orange
and found at the site of Love Canal.
 Carcinogenic
 Causes
reproductive problems: increases
likelihood of miscarriage, decreases fertility,
and sperm counts
 Also linked to diabetes, skin disorders,
immune deficiencies, and learning
disabilities
 Fat-soluble;
bioaccumulates in living
organisms
 93% of exposure is through meat and dairy
products
 It is hydrophobic and lipophilic (which
means when it gets into water, it will
rapidly accumulate in fish bodies)
 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?
 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
 Found in such varied items as heating coils,
carbonless carbon paper, power saws, cereal
boxes,varnishes, and bread wrappers.
 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
 Often

associated with exposure to pesticides:
These suppress the body’s natural defensive
mechanisms and make the body more vulnerable
to disease.
 Called
neurotoxins and affect the brain,
spinal cord and peripheral nerves
 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.
 Affect
the body’s hormones.
 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
 Ranch
minks
 Lake Apopka alligators
 Rats exposed to PCBs
 p-nonylphenol
 Florida panthers
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.
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.”
 Response
- type and amount of damage as a
result of exposure.



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.
 Case
reports
 Laboratory investigations
 Epidemiology (involves the study of various
human populations which have had exposure
to the chemical)
 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 LD50 of 50
milligrams or less per 1 kilogram of body
weight.
-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.
 Water
soluble
 Fat soluble
 an
increase in the concentration of a
chemical in specific organs or tissues
at levels higher than normally
expected.
 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.
i.
Examples: PCB’s. DDT,
radioactive isotopes
ii.
Passed to offspring through
gestation and nursing