Download File

Human Health and Environmental Risks
 Include physical risks
 Exposure to UV
radiation
 Include chemical risks
 Exposure to pesticides
 Include biological risks
 Pathogens and
diseases
 Include cultural risks
 Smoking, poor diet
 Are caused by
pathogens
 Can be chronic
 Act slowly over a long
period of time
 Heart disease
 Can be acute
 Act quickly over a
short period of time
 Ebola
 Plague
 Caused by bacterium Yersinia
pestis
 Transmitted by fleas
 Malaria
 Caused by parasitic protist
Plasmodium
 Transmitted by mosquitoes
 Tuberculosis (consumption)
 Caused by bacterium
Mycobacterium tuberculosis
 Transmitted by human breath
 Can be treated with antibiotics
or other drugs
 Can become resistant to drugs
 Are diseases that are
new to medicine
 Effective treatments
do not exist
 Are frequently
zoonoses
 Diseases that reside in
animal populations
and can infect humans
 Human Immunodeficiency Virus
(HIV)
 Crossed species from apes to
humans
 Transmissible in body fluids
 Attacks the immune system
 Antiviral drugs can reduce viral load
 Human Immune Deficiency
Syndrome (AIDS)
 Significantly weakened immune
system
 Death results from infection by other
pathogens
 Also crossed species
from apes to humans
 Unlike AIDS it kills its
primate hosts
 Natural host is unknown
 Cause massive bleeding
and organ failure
 Death rate is 60-90%
 Called Creutzfeldt-Jakob
Disease in humans
 Caused by mutated
proteins called prions
 Not destroyed by cooking
 Damages the brain and
nervous system
 Destroys motor coordination
 Can be transmitted from
infected meat
 Spread in cow population
from adding ground-up
remains from meat
processing
 Crossed species from
birds to humans
 Similar to virus that
caused 1918
worldwide pandemic
 Could mutate and
become far easier to
transmit
 Could cause another
pandemic
 Is transmitted by
mosquitoes
 Aggressive mosquito
control has limited the
virus in the US
 Causes brain
inflammation
 Is the study of harmful
chemicals (toxicants)
 Includes
 Neurotoxins
 Mutagens and
carcinogens
 Teratogens
 Allergens
 Endocrine disruptors
 Harm the nervous
system
 Include lead, mercury,
insecticides, and
chemical weapons
 Are chemicals that mutate
DNA
 Can cause cancer
 Include asbestos, radon,
benzene, formaldehyde,
and polycyclic aromatic
compounds (PAHs) from
smoke
 Can also include radiation
 Are chemicals that
interfere with normal
embryonic
development
 Include thalidomide,
alcohol, and
tetrahydrocannabinol
(THC)
 Can cause an
extreme reaction from
the immune system
that can lead to death
 Include dust, pollen,
nuts, milk, eggs,
wheat, soy, penicillin,
and codeine
 Are chemicals that interfere
with normal hormonal function
 Prevent normal hormonal
bonding to cell surfaces and
disrupt cell signaling
 Can interfere with gender and
developmental hormone
pathways
 Found in plastics and health
and beauty products
 Is the study of the
causes and duration
of disease in animals,
especially humans
 Looks for levels at
which toxicants cause
disease
 Establishes safe
levels of exposure in
the environment and
in tissues
 Expose organisms to
toxicants and observe
any changes
 Can be measured in
concentration of
chemical exposed
 Can also be measured
in the dose an
organism ingests
 Include the LD50 and
ED50
 LD50
 Are studies that measure
the lethal dose that kills 50%
of the test subjects
 ED50
 Are studies that measure
the effective dose that
causes nonlethal but
harmful effects in 50% of
test subjects
 Results from these studies
can be used to set safe
levels and exposures
 Invertebrates, fish, birds,
mammals
 Using the LD50 to
determine safe levels
for the environment
 Can calculate the safe
level by dividing LD50
by 10 (safe level =
10% of LD50)
2 mg/kg of mass/10 =
0.2 mg/kg of mass
 Safe exposures for
humans are set by
dividing the LD50 by
1000 (safe level =
0.1% of LD50)
2 mg/kg of mass/1000 =
0.002 mg/kg of mass
 Occurred in Bhopal, India in
1984
 Released methyl isocyanate
gas
 Worst industrial accident
ever
 2,000 people died in first 24
hours
 15,000 more died in the
weeks to follow
 As many as 500,000 injured
 Acute studies examine the
effects of toxicants over short
periods of time
 LD50, ED50
 Occur over hours to days
 Chronic studies examine the
effects of toxicants over long
periods of time
 Often follow test subjects for
years
 Retrospective studies monitor
organisms that have been
exposed to a toxicant
 Prospective studies monitor
organisms that may be exposed
to a toxicant
 Must compare group that is
exposed to a non-exposed
group
 Need to take into account
socioeconomic factors, and
exposure to multiple toxicants
 Synergistic effects can occur
from exposure to multiple
toxicants
 Are the same as those for
infectious diseases
 Can have multiple toxicants
from multiple sources
 Can be difficult to distinguish
which toxicant is causing which
symptoms
 Are affected by a toxicant’s
solubility
 Soluble toxicants have a
greater likelihood of becoming
part of a food chain
 Bioaccumulation and
biomagnification
 Is how long a toxicant
remains in the environment
 Depends on temperature,
humidity, pH, solubility,
radiation, and whether it
can be broken down by
bacteria
 May be different for the
same toxicant in water or in
soil
 Can be measured in halflives
 Pesticide DDT has a half-life
in soil of 30 years
 Identifies hazards and determines their potential
harm
 Can be qualitative
 Based on perceptions or personal values
 Can be quantitative
 Based on data
 Risk = proability of being exposed to a hazard X probability
of being harmed if exposed
 Perceived risk can be different than actual risk
 Is the level of risk that can be
tolerated
 Some individuals can tolerate
more risk than others
 EPA risk acceptance is usually
set at 1 in 1 million
 Case Study: PCBs
 PCBs in the Hudson River System
were high enough to ban fishing
 Fish were thought to be the main
vector for humans to acquire
PCBs
 Swimming and drinking water
were discouraged but not banned
 EPA recommended dredging river
bottom to remove PCBs
 Strikes a balance between
possible harm and other
interests
 Case Study: Arsenic
 EPA allowed levels of 50
μg/L in water for many years
even though the safe level
was 10 μg/l
 It was too expensive for
some municipalities to
remove that much arsenic
 Finally reduced levels to 10
μg/L when new research
showed that 5 μg/L was the
true safe limit
 Innocent-until-proven-guilty
principle
 Substances must be shown to be
harmful before they are treated as
toxicants
 Precautionary principle
 All potentially harmful substances are
assumed to be toxicants
 Case Study: Asbestos
 Use would have been regulated far
sooner and more lives would have
been saved under the precautionary
principle
 Stockholm Convention
 Established a list of 12
Persistent Organic
Pollutants (POPs) to be
banned outright or their
use reduced
 127 nations signed an
agreement to ban these
chemicals, phase out their
use, or severely restrict
their use
 Additional meetings have
added new chemicals to
the list each year since
2001
Name
Use
Aldrin
Pesticide
Chlordane
Pesticide
Dichlorodiphenyl
trichloroethane (DDT)
Pesticide
Dieldrin
Pesticide
Endrin
Heptachlor
Pesticide
Hexachlorobenzene
Pesticide
Mirex
Pesticide
Toxaphene
Pesticide
Polychlorinated
biphenyls (PCBs)
Industrial emissions
Polychlorinated
dibenzofurans
Industrial emissions
Dioxins
Industrial emissions
 REACH
 Registration, Evaluation,
Authorization and
restriction of CHemicals
 Puts the precautionary
principle into action
 Requires risk analysis of all
chemicals before they are
used industry or consumer
products
 Is the how the European
Union regulates toxicants