Lesson 9.1 An Overview of Environmental Health R 9 ...mrsburkey-science.weebly.com/uploads/1/2/6/9/12690679/envsci11_c0… · Lesson 9.1 An Overview of Environmental Health ... Natural

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9 Environmental Health

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R 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

• Social: Lifestyle choices that endanger health

• 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

Lesson 9.1 An Overview of Environmental Health

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.


Individual Responses

• Sensitivity to hazards varies

with age, sex, weight, and

immune system health.

•Many diseases have

genetic as well as

environmental factors.


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

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

• Spread by human and animal

contact and through contaminated

food and water

• Cause of almost half of all deaths

in developing nations

• Covering your mouth when you

cough, washing your hands often,

and staying home from school if

you’re sick help prevent the

spread of infectious disease.

Emerging Diseases

•Diseases appearing in the human population for the first time

or suddenly beginning to spread rapidly

•Humans have little or no resistance, and no vaccines have

been developed.

• Facilitated by

increasing human

mobility, growing

antibiotic

resistance, and

environmental

changes


Responding to Emerging Diseases

•World Health Organization (WHO):

Monitors health events worldwide and

coordinates international responses to

emerging diseases

•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

•Chemical mutagens: Chemicals that cause genetic mutations

• Teratogens: Chemicals that harm embryos and fetuses

•Neurotoxins: Chemicals that affect the nervous system

• Endocrine disruptors: Chemicals that interfere with the endocrine system

•Allergens: Chemicals that over-activate the immune system


Dust mite protein is a common

allergen.

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

Bioaccumulation and Biomagnification

•Bioaccumulation: The buildup of

toxic substances in the bodies of

organisms

•Biomagnification: The increased

concentration of toxic substances

with each step in a food chain

• Persistent organic pollutants are

biomagnified and stay in the

environment for long periods of time

and over long distances.


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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.

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.

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Lesson 9.1 An Overview of Environmental Health R 9 ...mrsburkey-science.weebly.com/uploads/1/2/6/9/12690679/envsci11_c0… · Lesson 9.1 An Overview of Environmental Health ... Natural