1. Toxicology and Human Health
Hazard Types
1) Cultural Hazards
- work conditions, health/lifestyle(nutrition, behavior)
2) Chemical Hazards
- chemicals in air, water, soil, food
3) Physical Hazards
- fire, earthquake, volcano, storms
4) Biological Hazards
- viruses, bacteria (disease causing agents)

2. Causes of Death in the U.S.
Deaths
442,000
Tobacco use
400,000
Excess weight
101,500 (43,450 auto)
Accidents
85,000
Alcohol use
75,000 (14,200 from AIDS)
Infectious disease
55,000
Pollutants/toxins
30,600
Suicides
Causes of Death in the U.S.
20,622
Homocides
17,000
Illegal drug use

3. © 2004 Brooks/Cole – Thomson Learning
Hazard
Shortens average life span in the United States by
Figure Page 430
Poverty
7-10 years
Born male
7.5 years
Smoking
6-10 years
Overweight (35%)
6 years
Unmarried
5 years
Overweight (15%)
2 years
Spouse smoking
1 year
Driving
7 months
Air pollution
5 months
Alcohol
5 months
Drug abuse
4 months
Flu
4 months
AIDS
3 months
Air Pollution
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

4. Toxicity of chemicals depends on:
1) Dose
2) Occurrence of exposure
3) Age, sex, health, DNA
4) Water-soluble vs. Fat-soluble
5) Persistence
6) Bioaccumulation
7) Biomagnification
8) Chemical Interactions
Poisonous?
- if LD50 is 50 mg or less per kilogram of body weight
- LD50 - median lethal dose
- amount needed in 1 dose to kill 50% of animals

5. Percentage of population killed by a given dose
100 75
Percentage of population killed by a given dose 50 25
LD50 2 4 6 8 10 12 14 16
Dose (hypothetical units)

6. Table 9-1 Toxicity Ratings and Average Lethal Doses for Humans
Supertoxic
Extremely toxic
Very toxic
Toxic
Moderately toxic
Slightly toxic
Essentially nontoxic
LD50 (milligrams per
kg of body weight)*
Less than 0.01
Less than 5
5–50
50–500
500–5,000
5,000–15,000
15,000 or greater
Average Lethal Dose†
Less than 1 drop
Less than 7 drops
7 drops to 1 teaspoon
1 teaspoon to 1 ounce
1 ounce to 1 pint
1 pint to 1 quart
More than 1 quart
Examples
Nerve gases, botulism toxin, mushroom toxins, dioxin (TCDD)
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

7. Chemical Hazards 1) Toxic Chemicals - cause 50% fatality
2) Hazardous Chemicals
- flammable, explosive, skin/lung irritant
3) Mutagens
- causes DNA mutations
- leads to genetic disorders
4) Teratogens
- causes birth defects
- ex. Lead, mercury, cadmium
5) Carcinogens
- cancer causing agents

8. Biological Hazards - lead to: A) Nontransmissable Diseases
- nonliving causes (can’t be passed)
- heart disease, diabetes, asthma OR
B) Transmissable Diseases
- caused by organisms (viruses, bacteria)
- most deadly:
1) Pneumonia & flu 5) Malaria
2) HIV/AIDS 6) Hepatitis B
3) Diarrheal diseases 7) Measles
4) Tuberculosis

9. Disease Transmission Affected By:
- travel
- migration to urban & rural areas
- poverty
- weather (floods, hurricanes, wind)
- introduction of alien species

10. Viruses Protozoa Bacteria
HIV
(AIDS)
Hepatitis B
Smallpox
Ebola
On this scale, a human hair would be 6 meters (20 feet) wide
1 micrometer
Protozoa
Plasmodium
(malaria)
10 micrometers
Bacteria
Vibrio cholerae
(cholera)
Myobacterium
tuberculosis
(tuberculosis)
Treponema pallidum (syphilis)
6 micrometers

11. Virus Infection Virus Cell membrane Host cell
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
Virus Infection
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.
New viruses
The new viruses emerge from
the host cell capable of infecting
other cells. This process often
destroys the first cell.

12. 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.
Dengue Fever

13. Malaria Endemic in more than 100 countries.
Caused by four protozoa species.
270–500 million new cases and
1 million deaths per year.
Malaria

14. Figure 19-14 Page 425 Malaria Transmission Anopheles mosquito (vector)
in aquatic breeding area
eggs
adult
larva
pupa
Malaria Transmission
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
2. Plasmodium
develops in
mosquito
3. Mosquito injects Plasmodium
sporozoites into human host

15. Yellow Fever Dreaded for 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.
Yellow Fever

16. 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

17. Solutions
Infectious Diseases
Increase research on diseases
Reduce poverty & malnutrition
Improve drinking water quality
Reduce unnecessary use of antibiotics
Careful hand washing
Immunize children
Global campaign to reduce HIV/AIDS