Download Toxicology

Environmental Health:
Risk, Toxicology, and
Human Health
Key Concepts
 Hazards people face
 Defining and measuring toxicology
 Chemical hazards
 Biological hazards
 Risk estimation, management, and reduction
Risk and Probability
Risk
Risk
assessment
Risk
management
Probability
Hazards
Cultural hazards
Physical hazards
Chemical hazards
Biological hazards
Hazards
Toxicology
Toxicity
Dosage
Bioaccumulation
Biomagnification
Synergism
Response
Acute effect
Chronic effect
Toxicology
Toxicology
Poisons
 Poison
 Median lethal
dose (LD50)
Dose-Response Curves
 Dose-response  Nonthreshold  Threshold
Table 9-1 Toxicity Ratings and Average Lethal Doses for Humans
Toxicity Rating
LD50 (milligrams per
kg of body weight)*
Average Lethal Dose†
Examples
Supertoxic
Less than 0.01
Less than 1 drop
Extremely toxic
Less than 5
Less than 7 drops
Nerve gases, botulism toxin,
mushroom toxins, dioxin (TCDD)
Very toxic
5–50
7 drops to 1 teaspoon
Toxic
50–500
1 teaspoon to 1 ounce
Moderately toxic
500–5,000
Slightly toxic
5,000–15,000
1 pint to 1 quart
Essentially nontoxic
15,000 or greater
More than 1 quart
1 ounce to 1 pint
Potassium cyanide, heroin, atropine,
parathion, nicotine
Mercury salts, morphine, codeine
Lead salts, DDT, sodium hydroxide,
sodium fluoride, sulfuric acid, caffeine,
carbon tetrachloride
Methyl (wood) alcohol, ether,
Phenobarbital, amphetamines (speed),
kerosene, aspirin
Ethyl alcohol, Lysol, soaps
Water, glycerin, table sugar
*Dosage that kills 50% of individuals exposed
†Amounts of substances in liquid form at room temperature that are lethal when given to a 70.4-kg (155-pound) human
Chemical Hazards
Hazardous chemicals
Mutagens
Teratogens
Carcinogens
Neurotoxins
Hormonally active agents
Precautionary principle
Endocrine Mimics
Hormone
Estrogen-like chemical
Anti-androgen chemical
Receptor
Cell
Normal Hormone Process
Hormone Mimic
Hormone Blocker
Biological Hazards: Diseases
Nontransmissible disease
Transmissible disease
Pathogens
Vectors
Tuberculosis
HIV/AIDS
Malaria
Malaria
Viruses
HIV
(AIDS)
Smallpox
Hepatitis B
Protozoa
Ebola
On this scale, a human hair would be 6 meters (20 feet) wide
1 micrometer
Plasmodium
(malaria)
Bacteria
Vibrio cholerae
(cholera)
Treponema pallidum (syphilis)
6 micrometers
Mycobacterium
tuberculosis
(tuberculosis)
10 micrometers
Dengue Fever
Painful and sometimes fatal.
Carried by four related viruses and strikes
during rainy season. 2.5 million people at risk;
50 million new cases a year.
Malaria
Endemic in more than 100 countries.
Caused by four protozoa species.
270–500 million new cases and
1 million deaths per year.
Yellow Fever
Dreaded far more than 400 years.
Viral disease that causes symptoms from
mild to severe illness and death. 200,000 new
cases and 30,000 deaths a year.
HIV Virus
Genetic material
Surface proteins
Virus
The virus attaches to the
host cell. The entire virus
may enter or it may inject
its genetic material, or genome.
Cell membrane
Host cell
The viral genetic
material uses the
host cell's DNA to
replicate again
and again.
New viruses
The new viruses emerge from
the host cell capable of infecting
other cells. This process often
destroys the first cell.
Each new copy of
the virus directs the
cell to make it a
protein shell.
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)
Tuberculosis
(bacteria)
1.9 million
1.7 million
Malaria
(protozoa)
1 million
Hepatitis B
(virus)
1 million
Measles
(virus)
800,000
Deaths per
100,000 people
<2.5
2.5-10
10-35
35-70
70-100
100+
Age
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
120
10
80
60
Female
40
20
0
20
Population (thousands)
40
60
80
100
120
Shortens average life span in the United States by
Hazard
Poverty
7-10 years
Born male
7.5 years
Smoking
6-10 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
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 campaign to reduce HIV/AIDS
Bioterrorism
 Possible targets: air, water, and food
 Inexpensive
Fairly easy to produce biological agents
Recombinant DNA techniques
Agent
Contagious
Symptoms
Mortality
(if untreated)
Existence
of vaccine
Treatment
Smallpox
(virus)
Yes
Fever, aches, headache, red
spots on face and torso
30%
Yes
Vaccination within 4 days after
exposure, IV hydration
Hemorrhagic
fever (viruses)
Yes
Vary but include fever,
bleeding, shock, and coma
Varies
No
Ebola has no cure, antiviral
riboflavin and some antibiotics
may help
Inhalation
anthrax
(bacterium)
No
Fever, chest pain, difficulty
breathing, respiratory failure
90–100%
Yes
Early treatment with Cipro and
other antibiotics
Botulism
(bacterium)
No
Blurred vision, progressive
60–100%
paralysis, death within 24 hours
if not treated
Yes
Equine antitoxin given early.
Intensive care, respirator
Pneumonic
plague
(bacterium)
Yes
High fever, chills, headache,
coughing blood, difficulty
breathing, respiratory failure
No
Antibiotics
90–100%
Antibiotics
No
Tularemia
(bacterium)
Fever, sore throat, weakness,
respiratory stress, pneumonia
30–60%
Yes
(in testing)
Risk Analysis
Risk analysis
Comparative risk analysis
System reliability
Risk management
Risk perception
Comparative Risk Analysis
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