Risk, Human Health, and Toxicology

1
Risk, Human Health, and Toxicology

• Chapter 14

2
Key Concepts

• Types of hazards people face
• Diseases in developed and developing countries
• Types of chemical hazards and how they are
  measured
• Estimating and perceiving risks

3
The Big Killer

• Tobacco
• Health threats
• Nicotine
• Passive smoking
• Costs of smoking
• Anti-smoking programs

Fig. 14-1, p. 327
4
The Big Killer
Deaths
Cause of Death
Tobacco use
442,000
Accidents
101,500 (43,450 auto)
Alcohol use
85,000
Infectious disease
75,000 (14,200 from AIDS)
Pollutants/toxins
55,000
Suicides
30,600
Homocides
20,622
Illegal drug use
17,000
Fig. 14-1, p. 327
5
Risk and Hazards

• Risk
• Probabilities
• Possibilities
• Risk assessment
• Risk management

6
Risk Assessment and Risk Management
Risk Assessment
Risk Management
Hazard identification What is the
hazard? Probability of risk How likely is the
event? Consequences of risk What is the
likely damage?
Comparative risk analysis How does it
compare with other risks? Risk reduction How
much should it be reduced? Risk reduction
strategy How will the risk be reduced? Financial
commitment How much money should be spent?
Fig. 14-2, p. 328
7
Major Types of Hazards

• Cultural
• Biological
• Chemical
• Physical

8
Biological Hazards

• Nontransmissible diseases
• Transmissible (infectious) diseases
• Pathogens
• Germ resistance to antibiotics

9
Global Threats from Disease

• Tuberculosis
• Viral diseases
• HIV and AIDS
• Malaria
• Reducing incidences of infectious diseases
• Bioterrorism

10
Seven 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. 14-3, p. 329
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Impact of AIDS on Age Structure of Botswana,
Africa
100 95-99 90-94 85-89 80-84 75-79 70-74 65-69 60-
64 55-59 50-54 45-49 40-44 35-39 30-34 25-29 20-24
15-19 10-14 5-9 0-4
With AIDS
Without AIDS
Male
Female
Age
120
40
20
0
60
80
10
20
100
120
80
60
40
Fig. 14-4, p. 331
Population (thousands)
12
Distribution of Malaria
Fig. 14-5, p. 331
13
Life Cycle of Malaria
Female mosquito bites infected human, ingesting
blood that contains Plasmodium gametocytes
Merozoites enter blood-stream and develop into
gametocytes causing malaria and making infected
person a new reservoir
Plasmodium develops in mosquito
Sporozoites penetrate liver and develop into
merozoites
Female mosquito injects Plasmodium sporozoites
into human host
Fig. 14-6, p. 332
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Solutions for Infectious Diseases
Solutions
Infectious Diseases
Increase research on tropical diseases and
vaccines Reduce poverty 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 campain to reduce
HIV/AIDS
Fig. 14-7, p. 333
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Characteristics of Agents that Could be Used as
Biological Weapons
Mortality (if untreated) 30 Varies 90100
60100 90100 3060
Existence of vaccine Yes No Yes Yes No
Yes (in testing)
Agent Smallpox (virus) Hemorrhagic fever
(viruses) Inhalation anthrax (bacterium) Botuli
sm (bacterium) Pneumonic plague (bacterium) Tu
laremia (bacterium)
Contagious Yes Yes No No Yes No
Symptoms Fever, aches, headache, red spots on
face and torso Vary but include fever, bleeding,
shock, and coma Fever, chest pain,
difficulty breathing, respiratory
failure Blurred vision, progressive paralysis,
death within 24 hours if not treated High fever,
chills, headache, coughing blood,
difficulty breathing, respiratory failure Fever,
sore throat, weak-ness, respiratory stress,
pneumonia
Treatment Vaccination within 4 days
after exposure, IV hydration Ebola has no cure,
antiviral riboflavin and some antibiotics may
help Early treatment with Cipro and other
antibiotics Equine antitoxin given
early. Intensive care, respirator Antibiotics
Antibiotics
Fig. 14-8, p. 334
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Chemical Hazards

• Toxic and hazardous chemicals
• Mutagens
• Teratogens
• Carcinogens
• Metastasis
• Effects on immune, nervous, and endocrine systems
• Neurotoxins
• Hormones
• Hormonally active agents (HAAs)
• PCBs, DDT, and certain herbicides

17
Toxicology

• Toxicity
• Dose
• Relevance of genetic makeup
• Multiple chemical sensitivity
• Solubility
• Water-soluble toxins
• Oil- or fat-soluble toxins
• Persistence
• Bioaccumulation and biomagnification

18
Toxicology

• Chemical interactions (antagonistic and
  synergistic)
• Acute toxic effects
• Chronic toxic effects
• The dose is the poison
• Toxicity varies with individuals
• How the human body disposes of chemical toxins
• Effects of trace levels of toxic chemicals

19
Estimating Toxicity

• Lethal dose (LD)
• LD50
• Toxicity ratings of various compounds (Table
  14-1, p. 337)
• Using case reports
• Epidemiological studies (experimental and control
  groups)
• Limits of epidemiological studies
• Laboratory studies
• Controversies with testing with animals
• Nonthreshold and threshold dose-response models

20
Dose-Response Curve
100
75
50
Percentage of population killed by a given dose
25
LD50
0
4
8
12
16
14
10
6
2
Dose (hypothetical units)
Fig. 14-9, p. 337
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Toxicity Ratings
Table 14-1, p. 337
22
Threshold and Nonthreshold Dose-Response Curves
Nonlinear dose-response
Linear dose-response
Effect
Effect
Threshold level
No threshold
Threshold
Fig. 14-10, p. 338
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Protection Against Harmful Chemicals

• Protecting children from toxic chemicals
• Why do we know so little about the harmful
  effects of chemicals?
• Lack of regulations
• Pollution prevention
• Precautionary principle
• Innocent until proven guilty approach
• Persistent organic pollutants (POPs) (dirty
  dozen)

24
Risk Analysis

• Risk analysis (risk assessment)
• Comparative risk analysis
• Risk management
• Risk communication
• Poverty the greatest risk
• Risks from lifestyle

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Comparative Risk Analysis
Comparative Risk Analysis
Most Serious Ecological And Health Problems

• 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

• Medium-Risk Ecological Problems
• Add deposition
• Pesticides
• Airborne toxic chemicals
• Toxic chemicals, nutrients, and sediment in
  surface waters

• Low-Risk Ecological Problems
• Oil spills
• Groundwater pollution
• Radioactive isotopes
• Acid runoff to surface waters
• Thermal pollution

Fig. 14-11, p. 340
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Estimating Risks from Technologies

• System reliability () Technology reliability x
  Human reliability
• Difficulties in estimating reliability
• Possible to achieve high reliability
• To err is human
• Automatic control systems

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Number of Deaths Per Year Globally
Cause of Death
Annual Deaths
Poverty/malnutrition/ disease cycle
11 million (75)
Tobacco
5 million (34)
Pneumonia/flu
3.2 million (22)
Air pollution
3 million (21)
HIV/AIDS
3 million (21)
Malaria
3 million (21)
Diarrhea
1.9 million (13)
1.7 million (12)
Tuberculosis
Auto accidents
1.2 million (8)
1.1 million (8)
Work related injury
Hepatitis B
1 million (7)
Measles
800,000 (5)
Fig. 14-12, p. 341
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Comparison of Risks
HAZARD
SHORTENS AVERAGE LIFE SPAN IN THE UNITED STATES BY
7-10 years
Poverty
Born male
7.5 years
Smoking
6-10 years
6 years
Overweight (35)
5 years
Unmarried
2 years
Overweight (15)
1 year
Spouse smoking
7 months
Driving
5 months
Air pollution
5 months
Alcohol
4 months
Drug abuse
4 months
Flu
3 months
AIDS
2 months
Air Pollution
1 month
Drowning
1 month
Pesticides
1 month
Fire
8 days
Natural radiation
5 days
Medical X rays
5 days
Oral contraceptives
4 days
Toxic waste
1 day
Flying
1 day
Hurricanes, tornadoes
10 hours
Living lifetime near nuclear plant
Fig. 14-13, p. 342
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Perceiving Risks

• Distorted perceptions of risks
• Degree of control
• Fear of the unknown and distrust of the new
• Whether we voluntarily take the risk
• Whether the risk is catastrophic
• Unfair distribution of risks
• Educating ourselves on risk
• Reducing risks in our own lives