Transcript Document

Risk, Toxicology, and Human Health
G. Tyler Miller, Jr.’s
Environmental Science
10th Edition
Chapter 10
Key Concepts
 Types of hazards people face
 Defining toxicology and measuring toxicity
 Types and measurement of chemical hazards
 Types of biological hazards (diseases)
 Risk estimation, management, and reduction
The Big Killer
 Tobacco
 Health hazards
 Nicotine
 Costs of smoking
Fig. 10-1, p. 203
 Antismoking programs
Risk and Probability
Risk
Risk
assessment
Risk
management
Probability
Fig. 10-2, p. 204
Major Types of Hazards
 Cultural
 Chemical
 Physical
 Biological
Fig. 19-1 p. 409
Toxicology
Toxicity
Dosage
Bioaccumulation
Biomagnification
Synergism
Response
Acute effect
Chronic effect
Variations in Sensitivity to a
Toxin within a Population
Number of individuals affected
© 2004 Brooks/Cole – Thomson Learning
Very
sensitive
0
Majority
of population
20
40
Dose (hypothetical units)
Very
insensitive
60
80
Fig. 10-3, p. 205
Bioaccumulation and
Biomagnification
Fig. 10-4, p. 205
Concerns about Trace Levels of
Toxic Chemicals
Concentration determines toxicity
“Dose makes the poison”
Tolerance varies with individuals
Natural isn’t always safe
Synthetic isn’t always bad
Analytical methods are improving
Poisons
 Poison
 Median lethal
dose (LD50)
Also see Table 10-1, p. 207
Fig. 10-5, p. 206
Estimating Toxicity
Case reports
Epidemiological studies
Laboratory animals
Animal welfare controversies
Dose-response curves
Reliability of toxicity estimates
Dose-Response Curves
 Dose-response  Nonthreshold  Threshold
Fig. 10-6 p. 207
Chemical Hazards
 Hazardous chemicals
 Mutagens
 Teratogens
 Carcinogens
 Metastasis
 Effects on immune, nervous and endocrine systems
 Hormonally active agents
Hormonally Active Agents
Hormone
Estrogen-like chemical
Antiandrogen chemical
Receptor
Cell
Normal Hormone Process
Hormone Mimic
Hormone Blocker
Fig. 10-7, p. 209
Biological Hazards: Diseases
 Nontransmissible disease
 Transmissible disease
 Pathogens (bacteria and viruses)
 Epidemiological transition
 Tuberculosis
 HIV/AIDS (viral)
 Malaria
Viruses
Pathogens
HIV
(AIDS)
Smallpox
Hepatitis B
Ebola
Protozoa
On this scale, a human hair would be 6 meters (20 feet) wide
1 micrometer
Bacteria
Vibrio cholerae
(cholera)
Plasmodium
(malaria)
Treponema pallidum (syphilis)
10 micrometers
Fig. 10-8, p. 210
6 micrometers
Myobacterium
tuberculosis
(tuberculosis)
Typical Virus
Genetic material
Surface proteins
Fig. 10-9a, p. 211
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
How a Virus
Reproduces
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.
Fig. 10-9b, p. 211
World’s Deadliest Infectious Diseases
Disease
(type of agent)
Deaths per year
Pneumonia and flu
(bacteria and viruses)
3.2 million
HIV/AIDS
(virus)
3.0 million
Diarrheal diseases
(bacteria and viruses)
1.9 million
Tuberculosis
(bacteria)
1.7 million
Malaria
(protozoa)
1 million
Hepatitis B
(virus)
1 million
Measles
(virus)
800,000
Fig. 10-10, p. 211
Current Tuberculosis Epidemic
Deaths per
100,000 people
<2.5
2.5-10
10-35
35-70
70-100
100+
Fig. 10-11, p. 212
World Distribution of Malaria
Fig. 10-12, p. 214
Malaria-free areas
Malaria largely eliminated
Malaria transmission areas
Anopheles mosquito (vector)
in aquatic breeding area
eggs
adult
Life Cycle
of Malaria
larva
pupa
1. Female
mosquito bites
infected human,
ingesting blood
that contains
Plasmodium
gametocytes
4. Parasite invades
blood cells, causing
malaria and making
infected person
a new reservoir
Fig. 10-13, p. 214
2. Plasmodium
develops in
mosquito
3. Mosquito injects Plasmodium
sporozoites into human host
Increase research on
tropical diseases and
vaccines
Reduce poverty
Ways to Prevent
or Reduce
Infectious
Diseases
Decrease malnutrition
Improve drinking water
quality
Reduce unnecessary
use of antibiotics
Educate people to take
all of an antibiotic
prescription
Reduce antibiotic use
to promote livestock
growth
Careful hand washing
by all medical personnel
Immunize children
against major viral
diseases
Oral rehydration for
diarrhea victims
Global campaign to
reduce HIV/AIDS
Fig. 10-14, p. 215
Risk Analysis
Risk analysis
Risk assessment
Comparative risk analysis
Risk management
Risk communication
Scientists
(Not in rank order
in each category)
Comparative
Risk Analysis
High-Risk Health Problems
• Indoor air pollution
• Outdoor air pollution
• Worker exposure to industrial
or farm chemicals
• Pollutants in drinking water
• Pesticide residues on food
• Toxic chemicals in consumer products
High-Risk Ecological Problems
• Global climate change
• Stratospheric ozone depletion
• Wildlife habitat alteration and destruction
• Species extinction and loss of biodiversity
Fig. 10-15, p. 216
Citizens
(In rank order)
High-Risk Problems
• Hazardous waste sites
• Industrial water pollution
• Occupational exposure
to chemicals
• Oil spills
• Stratospheric ozone depletion
• Nuclear power-plant accidents
• Industrial accidents releasing
pollutants
• Radioactive wastes
• Air pollution from factories
• Leaking underground tanks
Medium-Risk Ecological Problems
• Acid deposition
• Pesticides
• Airborne toxic chemicals
• Toxic chemicals, nutrients, and
sediment in surface waters
Medium-Risk Problems
• Coastal water contamination
• Solid waste and litter
• Pesticide risks to farm workers
• Water pollution from
sewage plants
Low-Risk Ecological Problems
• Oil spills
• Groundwater pollution
• Radioactive isotopes
• Acid runoff to surface waters
• Thermal pollution
Low-Risk Problems
• Air pollution from vehicles
• Pesticide residues in foods
• Global climate change
• Drinking water contamination
Greatest Risks to Humans
Poverty/malnutrition/
disease cycle
Tobacco
10 million (68)
4 million (27)
Pneumonia and flu
3.9 million (27)
Air pollution
3 million (21)
AIDS
3 million (21)
Diarrhea
2.1 million (14)
TB
1.6 million (11)
Malaria
1.1 million (8)
Work-related
injury and disease
Hepatitis B
1.1 million (8)
Automobile
accidents
Measles
Airline crashes
1 million (7)
885,000 (6)
800,000 (5)
1,126 (0.008)
© 2004 Brooks/Cole – Thomson Learning
Fig. 10-16, p. 217
© 2004 Brooks/Cole – Thomson Learning
Risk
Comparisons
Expressed in
Shorter
Average
Life Span
Shortens average life span in the United States by
Hazard
Poverty
7-10 years
Born male
7.5 years
Smoking
6 years
Overweight (35%)
6 years
Unmarried
5 years
2 years
Overweight (15%)
Spouse smoking
1 year
Driving
7 months
Air pollution
5 months
Alcohol
5 months
Drug abuse
4 months
Flu
4 months
AIDS
Air Pollution
3 months
2 months
Drowning
1 month
Pesticides
1 month
Fire
1 month
Natural radiation
8 days
Medical X rays
5 days
Oral contraceptives
5 days
Toxic waste
4 days
Flying
1 day
Hurricanes, tornadoes
1 day
Living lifetime near nuclear plant
10 hours
Fig. 10-17, p. 218
Estimating Risks with
Technological Systems
System reliability (%) = Technology reliability × Human reliability
 Difficulties in estimating reliabilities
 Possible to achieve high reliability
 “To err is human”
 Automated control systems
Perceiving Risks
Often poorly perceived by citizens
Distortions from the media and accidents
Distrust of the new
Underestimating risks with the familiar
Risks perceived as involuntary
Risks viewed as unnecessary
“Unfair” distribution of risks
Better education of public on risk needed