ENVIRONMENTAL SCIENCE

13e

14e

15e

CHAPTER 14:

Environmental Hazards

and Human Health

Fig. 14-1, p. 344

Core Case Study: BPA

Controversy (2) • Bisphenol A, an estrogen (Female hormone)

mimic

• Found in hardened Polycarbonate plastics

– Baby bottles

– Sipping cups

– Reusable water bottles

– Sports drink and juice bottles

– Microwave dishes

– Food storage containers

– Nearly all canned food liners

Core Case Study: BPA

Controversy (3)

• 93% of Americans have BPA in their

bodies

• Controversy over health risk

– Human health

– Fetuses

– Infants

Fig. 14-2, p. 344

14-1 What Major Health

Hazards Do We Face?

• Concept 14-1 People face health hazards

from biological, chemical, physical, and

cultural factors, and from the lifestyle

choices they make

• Risk - Probability

Risk assessment

Risk management

Fig. 14-3, p. 345

Major Types of Hazards

• Biological

• Chemical

• Physical

• Cultural

• Lifestyle

14-2 What Types of Biological

Hazards Do We Face?

• Concept 14-2 The most serious

infectious diseases are flu, AIDS,

tuberculosis, diarrheal diseases, and

malaria.

• Nontransmissible diseases

• Transmissible (infectious) disease

– Pathogens

• Epidemic*

• Pandemic**

* A large-scale outbreak of an

infectious disease in an area or

country.

** A global epidemic

Humans

Fetus and babies

Other humans

Water AirInsectsWild animalsLivestockPets Food

Stepped Art

Fig. 14-4, p. 348Pathways for infectious disease in humans.

Fig. 14-5, p. 348

Case Study: the Tuberculosis

Threat (1)

• TB spreading rapidly

• 1 in 3 infected; 5-10% will eventually

develop it

• 2008: 9.3 million active cases

– Poor countries in Asia and Africa

– ~ 1.6 million will die

Case Study: the Tuberculosis

Threat (2)

• Inadequate screening

• Increased resistance to antibiotics

• Increased person-to-person contacts

• Inadequate treatment

• Multidrug resistant TB

Science Focus:

Growing Resistance to Antibiotics

• High bacterial reproductive rate

• Genetic resistance

• Global travel

• Widely use of pesticides (cause an increase of

disease-transmitting species i.e. mosquitoes that resistance to

pesticides that once helped to control their populations)

• Overuse of antibiotics

Resistance geneTransfer from

antibiotic drug

(produce from weak

bacteria)

Most Deadly Viral Diseases

1. Influenza/flu

2. HIV – AIDS (27 million deaths, 1981-

2008)

3. Hepatitis B

4. Other viruses

– West Nile fever

– SARS (Severe acute respiratory distress

syndrome)

Case Study: HIV/AIDS

Epidemic (1)

• Acquired immune deficiency

syndrome

• Human immunodeficiency virus

• Spread by

– Unsafe sex

– Sharing needles

– Infected mother to child

– Exposure to infected blood

Case Study: HIV/AIDS

Epidemic (2)

• Living with AIDS 2008

– 33 million worldwide

– 2/3 in sub-Saharan Africa

– 1 million in the U.S.

– 2.7 million new cases

• 27 million deaths, 1981-2008

Case Study: Malaria

• 1 in 5 at risk

• Parasite spread by mosquitoes

• Kills 2700 people per day, mostly in

Africa

• Mosquito nets for beds

• Spray homes with DDT

Merozoites enter

bloodstream

and develop into

gametocytes

causing malaria

and making

infected person

a new reservoir

Sporozoites

penetrate liver

and develop

into merozoites

Female mosquito injects

Plasmodium sporozoites

into human host.

Plasmodium

develop in

mosquito

Female mosquito bites

infected human, ingesting

blood that contains

Plasmodium gametocytes

Fig. 14-7, p. 351

Fig. 14-6, p. 350

Distribution of malaria. About 40% of the world’s population

lives in areas in which malaria is prevalent.

Fig. 14-8, p. 351

Fig. 14-9, p. 352

14-3 What Types of Chemical

Hazards Do We Face?• Concept 14-3 There is growing concern

about chemicals that can cause cancer

and birth defects and disrupt the human

immune, nervous, and endocrine systems.

• Toxic chemicals

• Carcinogens

• Mutagens

• Teratogens (are chemicals that cause harm or birth

defects to a fetus or embryo)

Chemical Hazards

• Immune system disruptors

• Neurotoxins

• Hormonally active agents (HAA) can

mimic hormones. Exposure to low levels of HAAs can impair

reproductive systems and sexual development and cause physical

and behavioral disorders.

– DDT, PCBs, atrazine, aluminum, mercury,

BPA, PCBs

– Males of many species becoming more

feminine

– BPA of special concern

• Some chemicals such as As, methyl-Hg, and

dioxins can weaken the human immune system

and leave the body vulnerable to attacks by

allergens and infectious bacteria, viruses, and

protozoa.

• PCBs, Pb, methyl-Hg, As, and pesticide can

harm the human nervous system (brain, spinal

cord, and peripheral nerves) and cause

behavioral changes, learning disabilities,

retardation, attention deficit disorder, paralysis,

and death.

Chemical Hazards

• Low exposure of BPA causes a brain damage,

prostrate disease, breast cancer, early puberty,

reduced sperm count, impaired immune

function, type 2 diabetes, hyperactivity,

increased aggressiveness, impaired learning,

increased addiction to drugs such as

amphetamines, decreased sex drive in males.

Chemical Hazards

Fig. 14-10, p. 353

Atmosphere

Vegetation

Surface water

Vegetation

HumansAnimals

Crops

Soil

Potential pathways on

which toxic chemicals move through

the living and nonliving environment

Science Focus: Mercury (1)

• Nerve and organ damage

• Birth defects

• Natural sources

• Human activities

– Coal burning

Science Focus: Mercury (2)

• Humans exposed through

– Inhaling vaporized mercury and mercury

compounds

– Contaminated fish

– High fructose corn syrup

• 30,000 to 60,000 U.S. newborns likely have

reduced IQ

• Need to end coal burning and waste

incineration

Fig. 14-A, p. 354

Control

Sharply reduce mercury emissions

from coal-burning plants and

incinerators

Heavily tax each unit of mercury

emitted by coal-burning plants and

incinerators

Require labels on all products

containing mercury

Collect and recycle mercury-

containing electric switches, relays,

compact fluorescent lightbulbs, and

dry-cell batteries

Phase out waste incineration

Remove mercury from coal before it

is burned

Switch from coal to natural gas and

renewable energy resources such as

wind, solar cells, and hydrogen

Convert coal to liquid or gaseous fuel

Phase out use of mercury in

batteries, TVs, compact fluorescent

lightbulbs, and all other products

unless they are recycled

Solutions

Mercury Pollution

Prevention

14-4 How Can We Evaluate

Chemical Hazards?• Concept 14-4A Scientists use live

laboratory animals, case reports of

poisonings, and epidemiological studies to

estimate the toxicity of chemicals, but

these methods have limitations.

• Concept 14-4B We can reduce the major

risks we face by becoming informed,

thinking critically about risks, and making

careful choices.

Determining Chemical Safety

• Toxicology

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

• Dose

The effects of a particular chemical can

also depend upon by several factors i.e.

• Water and fat soluble toxins

• Persistence

• Biological magnification

The concentrations

of some potential

toxins in the

environment

increase as they

pass through the

successive

trophic levels of

food chains and

webs.

Type and Severity of Health

Damage

• Response – dose dependent

– Acute effect

– Chronic effect

Table 14-1, p. 357

Case Study: Protecting Children

from Toxic Chemicals

• Toxic chemicals in newborns’ blood

• Infants and children more susceptible

– Increased intake of air, water, food for

their body weights

– Put contaminated objects in their

mouths

– Less-developed immune systems

Estimating Toxicity

• Test on live animals

• Dose-response curve

– Lethal dose

– Median lethal dose (LD50)

• Extrapolation from data

Fig. 14-12, p. 360

Tennis shoesCan containphthalates

ToysVinyl toyscontainphthalates

ComputerFlame retardantcoatings of plasticcasing and wiring

Water bottleCan containbisphenol-A

FruitImported fruit maycontain pesticidesbanned in the U.S.

SofaFoam padding containsflame retardants andperfluorochemicals

TVWiring and plastic casingcontain flame retardants

CarpetPadding and carpet fiberscontain flame retardants,perfluorochemicals, andpesticides

MattressFlame retardants in stuffing

Baby bottleCan containbisphenol-A

ClothingCan containperfluorochemicals

Teddy bearSome stuffed animalsmade oversees containflame retardants and/orpesticides

ShampooPerfluorochemicalsto add shineNail polish

Perfluorochemicalsand phthalates

PerfumePhthalates

HairsprayPhthalates

FoodSome food containsbisphenol-A

MilkFat contains dioxinsand flame retardants

Frying panNonstick coating containsperfluorochemicals

Tile floorNonstick coating containsperfluorochemicals,phthalates, and pesticides

Some potentially harmful chemicals found in most homes.

Protection against Harmful

Chemicals

• Pollution prevention

• Precautionary principle

• Ban of 12 Persistent organic

pollutants (POPs) or the dirty dozen

14-5 How Do We understand Risks and

How Can We Avoid the Worst of Them?

• Concept 14-5 We can reduce the

major risks we face by becoming

informed, thinking critically about

risks, and making careful choices.

Evaluating Risks (1)

• Risk analysis (risk assessment)

• Comparative risk analysis

• Risk management

• Risk communication

• Poverty – the greatest risk

Fig. 14-3, p. 345

Evaluating Risks (2)

• Risks from lifestyles

– Don’t smoke

– Lose excess weight

– Eat healthy foods

– Exercise regularly

– Little or no alcohol

– Avoid excess sunlight

– Practice safe sex

Measles

Hepatitis B

Work-relatedinjury and disease

Malaria

Automobile accidents

Tuberculosis

Diarrhea

HIV/AIDS

Air pollution

Pneumonia and flu

Tobacco

Poverty/malnutrition/disease cycle

Cause of death

Annual deaths

11 million

(150)5.4 million (74)

3.2 million (44)

2.4 million (33)

2 million (27)

1.6 million (22)

1.5 million (21)

1.2 million (16)

1.1 million (15)

1 million (14)

1 million (14)

800,000 (11)

Fig. 14-13, p. 361

Fig. 14-15, p. 364

Fig. 14-15, p. 364

Cause of Death Deaths

442,000

101,500 (43,450 auto)

85,000

75,000 (16,000 from AIDS)

55,000

30,600

20,622

17,000Illegal drug use

Homicides

Suicides

Pollutants/toxins

Infectious

diseases

Alcohol use

Accidents

Tobacco use

Fig. 14-16, p. 364

Estimating Risks

from Technologies

• System reliability (%)

= Technological reliability x Human

reliability

• Difficulties in estimating reliability

• Perceived risk vs. actual risk

Improving Risk Evaluation

• Compare risks

• Determine how much risk you are

willing to accept

• Determine the actual risk involved

• Concentrate on evaluating and

carefully making important lifestyle

choices

Three Big Ideas from This

Chapter1. We face significant hazards from infectious

diseases and from exposure to chemicals that can

cause cancers and birth defects and disrupt the

human immune, nervous, and endocrine systems.

2. Because of the difficulty in evaluating the harm

caused by exposure to chemicals, many health

scientists call for much greater emphasis on

pollution prevention.

3. Becoming informed, thinking critically about risks,

and making careful choices can reduce the major

risks we face.

THE END