Transcript APES ch 11 - La Habra High School

Risk, Toxicology, and Human Health
G. Tyler Miller’s
Living in the Environment
13th Edition
Chapter 11
Dr. Richard Clements
Chattanooga State Technical Community College
Key Concepts
 Types of hazards people face
 Methods of toxicology
 Types and measurement of chemical hazards
 Types and effects of biological hazards
 Risk estimation, management, and reduction
Risk and Probability
Risk=
Probability of exposure X Probability of Harm
 Probability how risk is measured
Risk
assessment
Risk
management
Fig. 11-2 p. 229
Hazards
Cultural hazards
Unsafe working conditions, poor diet,
drugs, drinking, driving, criminal assault,
unsafe sex, poverty
Chemical hazards
Chemical in the air, water soil and food
Physical hazards
Ionizing radiation, fire, earthquake, volcanic
eruption, flood, tornadoes, and hurricanes
Biological hazards
Pathogens, pollen, and other allergens, and
animals (such as bees, and poisonous snakes)
Fig. 11-1 p. 228
Toxicology
Toxicity: measures how harmful a substance is.
Dose: the amount of potentially harmful substance that a
person has ingested, inhaled, or absorbed through the skin
Solubility: water soluble toxins and fat or oil soluble
toxins
Persistence: resistance to breakdown
Chemical Interactions: synergistic interaction,
and antagonistic interactions
Response:
type and amount of health damage that
results from exposure to a chemical or other agent
 Acute Effect
 Chronic Effect
Dose-affect Curve
1.
2.
3.
4.
5.
Size of dose
How often exposed
Who is exposed
How well the body’s detoxification system responds
Genetic makeup in regards to sensitivity (graph below)
Fig. 11-3
p. 230
DDT and Bioaccumulation(absorbed or
stored in organs) and Biomagnification
(through a food chain)
Fig. 11-4
p. 231
Poisons: “The dose makes the poison”
Paracelsus, 1540
 Poison: LD50 of 50 mg or
less/Kg of body weight
 LD50: median lethal
dose: the amount that in
one dose kills exactly 505 of
the animals in a test
population in a 14 day
period
See Table 11-1 p. 232
Fig. 11-5 p. 231
How to Estimate Toxicity
• Case Reports: usually made by physicians;
not very reliable; but do give clues to
suggest further laboratory tests
• Epidemiological studies: health of people
exposed to a toxin (experimental group) is
compared to a statistically similar group of
people not exposed to the toxin. Determine
if there is any statistically significant
association between exposure and health.
Many problems with this technique.
How to Estimate Toxicity
• Laboratory experiments: most widely sued
method: expose a population of live
laboratory animals (usu. Rats and mice) to a
measured dose of a specific substance under
controlled conditions. Take 2-5 years and
$200,000 – $2 million.
• More humane procedures increasing in use
Dose-Response Curves: acute
toxicity
 Dose-response  Nonthreshold  Threshold
Fig. 11-6 p. 233
Chemical Hazards
Hazardous chemicals
Mutagens
Teratogens
Carcinogens
Neurotoxins
Hormonally active agents
Precautionary principle
Hormonally Active Agents (HAA’s)
Hormone
Estrogen-like chemical
Antiandrogen chemical
Receptor
Cell
Normal Hormone Process
Hormone Mimic
Attach to estrogen receptor
molecules
Hormone Blocker
Prevent natural hormones
from attaching to their
receptors
Figure 11-7
Page 234
Biological Hazards: Diseases
Nontransmissible disease: disease that are
not caused by living organisms and not spread person
to person.
Transmissible disease: caused by a living
organism and spread person to person
Pathogens: infectious agents that cause disease
include viruses, bacteria, fungi, and protozoans
Vectors: agents that transmit disease such as
mosquito, fly, rat, etc.
Antibiotic resistance
Malaria
AIDS
See Case Study p. 241
Viruses
HIV
(AIDS)
Smallpox
Hepatitis B
Pathogens
Ebola
On this scale, a human hair would be 6 meters (20 feet) wide
Protozoa
1 micrometer
Bacteria
Vibrio cholerae
(cholera)
Treponema pallidum (syphilis)
6 micrometers
Myobacterium
tuberculosis
(tuberculosis)
Plasmodium
(malaria)
10 micrometers
Figure 11-8
Page 236
Genetic material
Virus
Structure
Surface proteins
Figure 11-9 (1)
Page 237
Virus Reproduction
The virus attaches to the
host cell. The entire virus
may enter or it may inject
its genetic material,
or genome.
Virus
Cell membrane
Host cell
The viral genetic
material uses the
host cell's DNA to
replicate again
and again.
Each new copy of
the virus directs the
cell to make it a
protein shell.
The new viruses emerge from
the host cell capable of infecting
other cells. This process often
destroys the first cell.
Antibiotic Resistance
Bacterial colony
Drug-resistant bacterium
Drug-resistant bacterial colony
Mutation
Antibiotic
Treating a colony of bacteria with an antibiotic kills most of the microbes. Sometimes, a
bacterium has a genetic mutation that makes it resistant to the drug. When the colony
grows back, all of its members will be descended from the drug-resistant survivor.
Harmful
microbe
Conjunction
Harmful
drug-resistant
microbe
Antibiotic
Drug-resistant bacterial colony
Harmless,
drug-resistant
microbe
Antibiotics attack harmless and harmful microbes. Drug resistance that develops in harmless
bacteria may be transferred to harmful bacteria. One bacterium attaches itself to another,
and a channel is opened between them in a process called conjugation. A copy of the
genes that make the microbe resistant can then be passed from one microbe to the other.
In-text figure
Page 238
Antibiotic
World HIV Distribution in 2001 (number of
deaths due to AIDS)
North America
940,000 (20,000)
Eastern Europe
& Central Asia
1 million (23,000)
Western Europe
560,000 (6,800)
Caribbean
420,000 (30,000)
Latin America
1.4 million (80,000)
East Asia & Pacific
1 million (35,000)
North Africa
& Middle East
440,000 (30,000)
South &
Southeast Asia
6.1 million (400,000)
Sub-Saharan Africa
28.1 million (2-3 million)
Figure 11-10
Page 240
Australia &
New Zealand
15,000 (120)
Synergy between AIDS/TB/ Malnutrition
HIV/AIDS
• HIV immune
suppression
facilitates active
TB development
• AIDS can lead to job
loss and poverty
Malnutrition
Figure 11-11
Page 240
TB
• Malnutrition weakens
body and may
facilitate HIV
transmission
and progress
• TB can lead
to job loss and
malnutrition
because of
lack of money
• Malnutrition may
facilitate development
of active TB
• Active TB facilitates
HIV replication
and speeds up
HIV progression
Malaria Life Cycle and Infection
Fig. 11-14 p. 243
Global TB Epidemic
Deaths per
100,000 people
<2.5
2.5-10
10-35
35-70
70-100
100+
In-text figure
Page 241
Worldwide Malaria Distribution Figure 11-12
Page 243
Malaria-free areas
Malaria largely eliminated
Malaria transmission areas
Risk Analysis
Risk analysis
Comparative risk
analysis
Cost-benefit
analysis
Risk management
Risk perception
Fig. 11-17
p. 247