9 Environmental Health C

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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,& other orgs that cause disease

• Social: Lifestyle choices that endanger health

• Chemical: Harmful artificial & natural chems in env’t

• Physical: Natural disasters & others as UV radiation, that can cause health problems

Lesson 9.1 An Overview of Environmental Health

Epidemiology

• Study of disease in human

pops—how & where they

occur & how they can be

controlled

• Involves studying large grps

over long periods

• Can determine statistical

associations betwn health

hazards & effects, but can’t

prove the hazards actually

caused effects

Lesson 9.1 An Overview of Environmental Health

Toxicology

• Study of how poisonous subs

affect an org’s health

• Toxicity: measure of how

harmful a sub is.

• Toxicologists look at toxicity

by determining dose-

response relationships.

Lesson 9.1 An Overview of Environmental Health

Individual Responses

• Sensitivity to hazards varies

with age, sex, weight, &

immune system health.

•Many diseases have

genetic as well as env’tal

factors.

Lesson 9.1 An Overview of Environmental Health

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.

Risk Assessment

• Risk: probability that a

hazard will cause harm

• Risk assessment: The

process of measuring risk

• Takes into account:

• 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 & animal

contact & thru contaminated

food & water

• Cause of almost half of all deaths

in developing nations

• Prevention of

spread of infectious disease:

Cover mouth when cough, wash

hands often, & stay home from

school if sick

Emerging Diseases

•Diseases appearing human pop for the 1st time or suddenly

beginning to spread rapidly

•Humans have little/no resistance & no vaccines have been

dev.

• Facilitated by

increasing human

mobility, growing

antibiotic

resistance, &

env’tal

changes

Lesson 9.2 Biological and Social Hazards

Responding to Emerging Diseases

•World Health Organization (WHO):

Monitors health events worldwide &

coordinates international responses to

emerging diseases

•Centers for Disease Control and

Prevention (CDC): Responds to

emerging diseases in the United States;

CDC dev pandemic plans to deal w/

spread of H1N1 flu virus.

Lesson 9.2 Biological and Social Hazards

H1N1 Virus

Social Hazards

Lesson 9.2 Biological and Social Hazards

• Some easier to avoid than

others

• Ex: smoking, being exposed

to secondhand smoke, living

near an old toxic waste site,

working w/ harmful

chemicals & eating fatty

foods

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 harmful in large enough amts

• Pollutant: released into envt--some harmful impact on

people & org

•Chemical hazards: not necessarily pollutants & pollutants

are not necessarily chemical hazards.

Lesson 9.3 Toxic Substances in the Environment

Oil Pollution

Types of Chemical Hazards

•Carcinogens: Cancer-causing chemicals

•Chemical mutagens: Chemicals cause genetic mutations

• Teratogens: Chemicals harm embryos & fetuses

•Neurotoxins: Chemicals that affect nervous system

• Endocrine disruptors: Chemicals that interfere w/ the endocrine system

•Allergens: Chemicals that over-activate the immune system

Lesson 9.3 Toxic Substances in the Environment

Dust mite protein is a common

allergen.

Indoor Chemical Hazards

Lesson 9.3 Toxic Substances in the Environment

Sources of Outdoor Chemical Hazards

• In the air: Natural sources-

volcanic eruptions human

sources-pesticides

• In the ground: Pesticide

use, improper disposal of

electronics, etc.

• In the water: Chem runoff

from land or direct drainage

of toxic subs into water

Lesson 9.3 Toxic Substances in the Environment

A leaking oil line

Bioaccumulation and Biomagnification

•Bioaccumulation: buildup of toxic

substances in the bodies of orgs

•Biomagnification: increased conc

of toxic substances w/ each step in

food chain

• Persistent organic pollutants are

biomagnified & stay in the env’t for

long periods of time & over long

distances.

Lesson 9.3 Toxic Substances in the Environment