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Environmental Health

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

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 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.

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

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

Swine Flu Could Be a Global Pandemic

Watch the ABC News video Swine Flu Could Be a Global Pandemic. Have students use their own experiences to talk about how the spread of H1N1 virus was controlled in the months after the video was made. Then, discuss the ways that biological hazards are monitored and controlled by national and international agencies.

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.

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.

Bioaccumulation

Feed the bird

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?