environmental health the rise and fall—and er … · er 9 environmental health the rise and...

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9 Environmental Health C

HA

PTER The Rise and Fall—and

Rise?—of DDT

• DDT is the least expensive way of killing the mosquitoes that cause malaria. • DDT harms fish and birds, and can cause liver damage, cancer, and convulsions in humans. • In the 1970s many countries banned the use of DDT, but some African countries have resumed its use to control malaria.

Talk About It Evidence shows that DDT damages ecosystems but helps eradicate malaria in areas where millions of people die of the disease each year. Should DDT be used in malaria-stricken areas? Why or why not?

Lesson 9.1 An Overview of Environmental Health

One third of death and disease in the least developed nations is a direct result of environmental causes.

Types of Environmental Health Hazards

•  Biological: Viruses, bacteria, and other organisms that cause disease •  Example: Flu Virus

•  Social: Lifestyle choices that endanger health •  Example: Smoking

•  Chemical: Harmful artificial and natural chemicals in the environment

•  Physical: Natural disasters and ongoing natural phenomena, such as UV radiation, that can cause health problems


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Epidemiology

•  The study of disease in human populations—how and where they occur and how they can be controlled

•  Often involves studying large groups over long periods

•  Can determine statistical associations between health hazards and effects, but can’t prove the hazards actually caused the effects


Toxicology

• The study of how poisonous substances affect an organism’s health

• Toxicity is a measure of how harmful a substance is.

• Toxicologists look at toxicity by determining dose-response relationships.


Dose-Response Relationship

• Dose: amount of a substance an organism is exposed to. • Concentration

•  Length of exposure

• Response: Effect on organism

• Threshold Dose: sometimes a little is ok. Once exposure passes the threshold the response begins.


Individual Responses

• Everyone responds differently

• Sensitivity to hazards varies with age, sex, weight, and immune system health. • A medication that is fine for adults

may cause birth defects.

• Many diseases have genetic as well as environmental factors. • Smoking could increase your risk of

lung cancer

• Having the BRCA gene increases your risk of breast cancer


Did You Know? Thalidomide, a drug that currently shows promise for treatment of Alzheimer's, AIDS, and some cancers, caused thousands of severe birth defects when it was used as an anti-nauseal in the 1950s and 60s.

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Risk Assessment

•  Risk: The probability that a hazard will cause harm

•  Risk Assessment: The process of measuring risk

•  Takes into account: •  The type of hazard

•  How frequently humans will be exposed to it

•  How sensitive people are to it

•  Governments can take this information into account when making policies.

Lesson 9.1 An Overview of Environmental Health Lesson 9.2 Biological and Social Hazards

Three quarters of infectious disease deaths are caused by five types of diseases: respiratory infections, AIDS, diarrheal diseases, tuberculosis, and malaria.

Tuberculosis-causing bacteria

Infectious Diseases

Lesson 9.2 Biological and Social Hazards

Did You Know? In 2002, AIDS killed about 2 million people worldwide— almost equal to the entire population of Arkansas.

• Caused by pathogens (virus or bacteria)

• Spread by human and animal contact and through contaminated food and water

•  Vector organisms can spread disease

•  Examples: ticks and mosquitos

• Cause of almost half of all deaths in developing nations

Preventing Infectious Diseases


• We can take steps to easily prevent the spread

•  Covering your mouth when you cough

•  Washing your hands •  Staying home from school if

you’re sick •  Limit exposure to vector

organisms •  Providing proper sanitation

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Emerging Diseases • Emerging Diseases: Diseases appearing in the human population for the first time or suddenly beginning to spread rapidly

• Problem because…Humans have little or no resistance, and no vaccines have been developed.


How Emerging Diseases Spread

• Increasing human mobility around globe (travel) • We move around more quickly now (planes)

• Growing antibiotic resistance

• Environmental changes • Example: logging may expose workers to new diseases carried by forest animals.

• Climate change could increase warm areas where diseases can live.


Responding to Emerging Diseases

International Response

• World Health Organization (WHO): Monitors health events worldwide and coordinates international responses to emerging diseases

National Response

• Centers for Disease Control and Prevention (CDC): Responds to emerging diseases in the United States; the CDC developed pandemic plans to deal with the spread of the H1N1 flu virus.


H1N1 Virus

Social Hazards


• Some social hazards are easier to avoid than others.

• Examples of social hazards include smoking, being exposed to secondhand smoke, living near an old toxic waste site, working with harmful chemicals, and eating fatty foods.

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Lesson 9.3 Toxic Substances in the Environment

Chemicals are all around us, and all of them can be harmful to our health in large enough amounts. In other words, “The dose makes the poison.”

Chemical Hazards • Any chemical can be harmful in large enough amounts.

• A pollutant is something released into the environment that has some harmful impact on people and other organisms.

• Chemical hazards are not necessarily pollutants, and pollutants are not necessarily chemical hazards.


Oil Pollution

Types of Chemical Hazards • Carcinogens: Cancer-causing chemicals

• Example: Cigarette smoke

• Chemical mutagens: Chemicals that cause genetic mutations • Example: Benzene (in smoke and air pollution)

• Teratogens: Chemicals that harm embryos and fetuses • Example: Thalidomide (sleeping pill)


Types of Chemical Hazards • Neurotoxins: Chemicals that affect the nervous system • Examples: Lead, mercury, pesticides

• Endocrine disruptors: Chemicals that interfere with the endocrine system • Example: PCBs (found in contaminated

water)

• Allergens: Chemicals that over-activate the immune system • Examples: Mold, pollen


Dust mite protein is a common allergen.

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Indoor Chemical Hazards


Sources of Outdoor Chemical Hazards • In the air: Natural sources, such as volcanic eruptions, or human sources, such as pesticides

• In the ground: Pesticide use, improper disposal of electronics, etc.

• In the water: Chemical runoff from land or direct drainage of toxic substances into water


A leaking oil line

Toxic Concentrations Bioaccumulation • Chemical in the environment doesn’t/slowly breaks down • Plants and animals ingest or breath it in • Chemical accumulates in bodies over time • Can kill organisms on different trophic levels

Biomagnification • Chemical concentration in organisms increases with each trophic level • Affects higher trophic levels more

Pesticides

• Some pesticides decompose soon after applied • Round-up breaks down

when it touches soil • Non biodegradable pesticides enter the food chain • Move up trophic levels • Examples: DDT,

Dieldrin, and Aldrin •  Stored in fatty tissues

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Think-Pair-Share

• Are there more predators or prey?

• Why?

Biomagnification •  Pyramid structure affects

the functioning of an ecosystem.

•  Higher trophic levels get more.

Top Carnivores

• Highest trophic level most susceptible to environmental change • Why?

• Limited diet • Low population numbers b/c low

energy available • One death is a bigger deal

• Examples: • DDT and peregrine falcon • PBDE (polybrominated diphenly) and

polar bears

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Lesson 9.4 Natural Disasters

Although we cannot prevent most natural disasters, there are steps that scientists, engineers, governments, and citizens can take to resist damage and deal with the aftermath.

A landslide caused by the Great Sichuan Earthquake in Sichuan Province, China

Earthquakes


• Earth’s crust is broken into large pieces called tectonic plates, which float on a layer of molten rock.

• Earthquakes tend to occur along active plate boundaries.

• Earthquakes can damage structures and trigger landslides and tsunamis.

• Openings in Earth’s crust that eject molten lava and other materials

• Ash and gases from volcanic eruptions can block sunlight, causing temperatures to drop.

• Eruptions can trigger landslides and mudflows.

• Molten lava can cover and destroy surrounding land.

Volcanoes


Did You Know? In 1991, Mount Pinatubo erupted in the Philippines, covering the area around the volcano with a layer of volcanic

materials up to 180 m (600 ft) thick.

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Storms • Tornadoes: Rotating funnels of air that can travel over 400 km (250 mi) per hr

• Hurricanes: Storms that form over tropical oceans, with winds over 119 km (74 mi) per hour

• Thunderstorms: Produce lightning and thunder, usually with heavy rain


Did You Know? Hurricane Katrina, which struck New Orleans in 2005, caused more than $80 billion in damage and killed 1800 people.

Avalanches

•  Masses of snow that slide down a slope •  Conditions favoring avalanches:

•  Slope greater than 30 degrees •  Unstable snowpack •  Heavy snowfall •  Warm temperatures


Did You Know? A big North American avalanche can contain 230,000 m3 of snow—about the equivalent of 20 football fields filled with snow 3 m (10 ft) deep.

environmental health the rise and fall—and er … · er 9 environmental health the rise and...

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