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