Transcript Links Between the Environment and Human Health

Links Between the Environment
and Human Health
BLS Environmental Science
Environmental Health
Part I
Environmental Health
• Within the human environment, there are
hazards that can make us sick, cut our lives short,
or contribute in other ways to human misfortune.
• In the context of environmental health, a hazard
is anything that can cause
– 1) injury, disease, or death to humans
– 2) damage to personal or public property
– 3) deterioration or destruction of environmental
components.
How do you measure
the Picture of Health?
• Unfortunately, measuring all these dimensions
of health for a society is virtually impossible.
Thus, to study environmental health, we will
focus on disease and consider health to be
simply the absence of disease.
Public Health: How do you define it?
• Each state also has a health department, and
most municipalities have health agents. In
addition, there is a huge health care industry
in the United States, with federal programs
such as Medicare and Medicaid, hospitals,
health maintenance organization, and local
physician and other health professionals.
Public Health: How do you define it?
• 1. Other Countries “Virtually every country has
a similar ministry of health that acts on behalf of
its people to manage and minimize health risks.”
• 2. Life Expectancy “In 1955, average life
expectancy globally was 48 years. Today it is 68
years and rising gradually.”
• 3. Two Worlds “The countries of the world have
undergone the epidemiologic transition to
different degrees, with very different
consequences.”
Environmental Hazards
Part II
Environmental Hazards
• There are two fundamental ways to consider
hazards to human health.
• One is to regard the lack of access to
necessary resources as a hazard.”
• Another way is to focus on the exposure to
hazards in the environment.
Cultural Hazards
• Many of the factors that contribute to
mortality and disability are a matter of choice
or at least can be influenced by choice. People
engage in risky behavior and subject
themselves to hazards.
Cultural Hazards
Biological Hazards
• Approximately one-fourth of global deaths are
due to infectious and parasitic diseases.
• Biological Hazards
Tuberculosis
• Although AIDS has overtaken tuberculosis as
the disease that causes the most adult deaths,
tuberculosis continues to be a major killer.
Tuberculosis
Malaria
• Of the infectious diseases present in the
tropics, malaria is by far the most serious,
accounting for an estimated 247 million cases
each year and 881,000 deaths.
• See Figure 17.6
Physical Hazards
• Natural disasters—including hurricanes,
tornadoes, floods, forest fires, earthquakes,
landslides, and volcanic eruptions—take a toll
of human life and property every year. They
are the outcome of hydrological,
meteorological, or geological forces.
Physical Hazards
• Natural disasters include hurricanes, tornadoes, floods,
fires, earthquakes, landslides, and volcanic eruptions
– The result of hydrological, meteorological, or geological
forces
• Unimaginably dreadful events occurred in 2004-2005
– The Indian Ocean tsunami, Hurricane Katrina, Pakistan’s
earthquake
• Some hazards can’t be anticipated (tornadoes,
earthquakes)
– Others occur because of where people decide to live.
Physical Hazards
Out of Nowhere
• The U.S. has 780 tornadoes/year, more than
any other place
– They are spawned from severe weather
– Winds can reach 300 mph
– They can kill hundreds
• Some natural disasters are unavoidable
– Earthquake-resistant buildings can be constructed
– Tsunami early warnings are increasing
• The poor are the least capable of anticipating
and dealing with disasters
In Harm’s Way
• Much loss from natural disasters is due to poor
environmental stewardship
– Deforested hillsides
– Building on floodplains, below volcanoes, on geologic
faults, marshes, and mangrove forests
• People assume disasters happen to other people
– They take risks to live in desirable places
• Stupid zones could be created for areas that
shouldn’t be built
– Areas prone to hurricanes, earthquakes, volcanoes,
etc.
Chemical Hazards
• Industrialization has resulted in technologies that
use chemicals
– Cleaning agents, pesticides, fuels, medicines, paints,
etc.
• Exposure is through ingestion, breathing, the
skin, direct use, or by accident
• Toxicity: condition of being harmful, deadly, or
poisonous
– Depends on exposure and dose (the amount
absorbed)
• Different people have different thresholds of
toxicity
– Children and embryos are most sensitive
Carcinogens
• Many chemicals are hazardous even at very low
levels
– Heavy metals, organic solvents, pesticides
• Acute poisoning episodes are understandable and
preventable
– But it is hard to determine effects of long-term
exposure to low levels of substances
• Carcinogens: cancer-causing agents
– Cancer develops over decades, so it is hard to connect
cause with the effect
– There are 51 known and 188 suspected carcinogens
• Developing nations have rising exposure to
chemicals