Transcript No Slide Title

Toxicology and Human
Health
Toxicology and Human
Health
• Risk and Hazards
– Risk - the possibility of suffering harm
from a hazard that can cause injury,
disease, economic loss, or
environmental damage
Toxicology and Human
Health
• Risk and Hazards
– Probability - a mathematical
statement about how likely it is that
some event will occur
• Ranges from 0 ( absolute certainty of no
risk) to 1 (absolute certainty of risk)
Toxicology and Human
Health
• Types of Hazards
– Cultural Hazards
• Poor diet
• Unsafe sex
– Chemical Hazards
• Harmful chemicals in air, water, soil, food
Toxicology and Human
Health
• Types of Hazards
– Physical Hazards
• Ionizing radiation
• Noise
• Natural disasters
– Biological Hazards
• Pathogens
• Allergens
• Animals
Toxicology and Human
Health
• Toxicology
– Toxicology - the study of the adverse
effects of chemicals on human health
– Toxicity - a measure of how harmful a
substance is
Toxicology and Human
Health
• Toxicology
– Pathways of Exposure
• Inhalation
• Ingestion
• Absorption chemicals on human health
Toxicology and Human
Health
• Toxicology
– Dose and Response
• Dose - the amount of a potentially
harmful substance a person has ingested,
inhaled, or absorbed
• Response - the amount of damage to
health per given dose
Toxicology and Human
Health
• Toxicology
– Types of Responses
• Acute Response - an immediate or rapid
harmful reaction to an exposure
• Chronic Response - a permanent or long-
lasting reaction to an exposure
Toxicology and Human
Health
• Toxicology
– Factors Affecting Dose and Response
• Bioaccumulation - an increase in the
concentration of a chemical in a specific
organ at a level higher than would
normally be expected
Toxicology and Human
Health
• Toxicology
– Factors Affecting Dose and Response
• Biomagnification -an increase in the
concentration of certain slowlydegradable fat-soluble compounds in
organisms at successively higher trophic
levels in a food chain
Bioaccumulation and Biomagnification
Toxicology and Human
Health
• Toxicology
– Lethal Dose and Poison
• Median Lethal Dose (LD50) - the amount
of a chemical received in one dose that
will kill exactly 50% of all test animals
within a 14 day test period
• Poison - a chemical with an LD50 </= 50
milligrams per kilogram of body weight
Toxicology and Human
Health
• Toxicology
– Methods of Determining Toxicity
• Case Reports
• Laboratory Investigations
• Epidemiology
Toxicology and Human
Health
• Chemical Hazards
– Toxic Chemicals - substances that are
fatal to > 50% of test animals at a
given concentration
Toxicology and Human
Health
• Chemical Hazards
– Hazardous Chemicals - chemicals that
cause harm by:
• Being flammable or explosive
• Irritating or damaging skin or lungs
• Interfering/preventing oxygen uptake
• Inducing allergic reactions of the immune
system
Toxicology and Human
Health
• Chemical Hazards
– Mutagens - chemicals that cause
random mutations
• Radiation
Toxicology and Human
Health
• Chemical Hazards
– Teratogens - chemicals, radiation,
viruses that cause birth defects
during development of human
embryo
• PCBs
• Thalidomide
• Steroid hormones
• Heavy metals
Toxicology and Human
Health
• Chemical Hazards
– Carcinogens - chemicals, radiation,
viruses that cause/promote growth of
malignant tumors
Toxicology and Human
Health
• Chemical Hazards
– Carcinogens
• Major Sources
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Cigarette Smoke (30-40%)
Diet (20-30%)
Occupational Exposure (5-15%)
Environmental Pollutants (1-10%)
Toxicology and Human
Health
• Chemical Hazards
– Impacts on the Immune System
• Immune System - cells and tissues that
protect the body from disease by forming
antibodies to invading agents and
rendering them harmless
Toxicology and Human
Health
• Chemical Hazards
– Impacts on the Immune System
• Synthetic chemicals
• HIV virus
• Ionizing radiation
Toxicology and Human
Health
• Chemical Hazards
– Impacts on the Immune System
• Weakening of immune system and attack
by allergens, infectious bacteria, viruses,
protozoans
Toxicology and Human
Health
• Chemical Hazards
– Impacts on the Nervous System
• Components of the Nervous System
– Brain
– Spinal Cord
– Nerves
Toxicology and Human
Health
• Chemical Hazards
– Impacts on the Nervous System
• Neurotoxins - chemicals that attack nerve
cells
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Chlorinated hydrocarbons
Organophosphate pesticides
Formaldehyde
Heavy metals
Industrial solvents
Toxicology and Human
Health
• Chemical Hazards
– Impacts on the Endocrine System
• Endocrine System - organs and tissues
whose actions are coordinated by
chemical messengers called hormones
Toxicology and Human
Health
• Chemical Hazards
– Impacts on the Endocrine System
• Hormones control:
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Sexual reproduction
Growth
Development
Behavior
Toxicology and Human
Health
• Chemical Hazards
– Impacts on the Endocrine System
• Endocrine Disrupters
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Undersized penises
Low testosterone levels
Hyperactivity
Vaginal cancer
Malformed testicles
Retardation
Endometriosis
Toxicology and Human
Health
• Biological Hazards
– Types of Diseases
• Transmissible Disease - a disease caused
by a living organism which can be spread
from one person to another
– Pathogens - disease-causing organisms
• Bacteria - single-celled organism
• Viruses - noncellular infectious agent
• Parasites - (tapeworm)
• Protozoa - (amoeba)
Toxicology and Human
Health
• Biological Hazards
– Types of Diseases
• Transmissible Disease
– Sources of Exposure
• Air
• Water
• Food
• Body fluids
• Insects
• Non-human carriers (vectors)
Toxicology and Human
Health
• Biological Hazards
– Types of Diseases
• Seven Dealiest Transmissible Diseases
– Acute Respiratory Infections
• Bacteria, Viruses (4.7 million deaths)
– Diarheal Diseases
• Bacteria, Viruses (3.1 million deaths)
• Dysentery
Toxicology and Human
Health
• Biological Hazards
– Types of Diseases
• Seven Dealiest Transmissible Diseases
– Tuberculosis
• Bacteria (3.1 million deaths)
– Malaria
• Parasitic protozoa (Plasmodium)
• 2.1 million deaths annually
Toxicology and Human
Health
• Biological Hazards
– Types of Diseases
• Seven Dealiest Transmissible Diseases
– AIDS
• HIV (1.7 million deaths)
– Hepatitis B
• Virus (1 million deaths)
– Measels
• Virus (1 million deaths)
Toxicology and Human
Health
• Biological Hazards
– Types of Diseases
• Seven Dealiest Transmissible Diseases
– LDCs
• Infectious diseases account for 42% of all
deaths annual
• 27,000 deaths per day due to infectious
diseases
Toxicology and Human
Health
• Biological Hazards
– Types of Diseases
• Nontransmissible Diseases
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Cardiovascular disorders
Cancer
Diabetes
Malnutrition
Bronchitis
Emphysema
Toxicology and Human
Health
• Biological Hazards
– Types of Diseases
• Tuberculosis
– Bacterial Disease
– Airborne droplets of body fluids spread by
coughing, sneezing, talking, singing
– 95% of all new cases occur in LDCs
– Rapid reemergence
Toxicology and Human
Health
• Biological Hazards
– Types of Diseases
• Tuberculosis
– Causes of reemergence
• Poor screening and control programs
• Development of genetically resistant
strains of bacteria to antibiotics
• Population growth and urbanization
• Spread of AIDS
Toxicology and Human
Health
• Biological Hazards
– Types of Diseases
• Influenza
– Viral Disease
– Transmitted by body fluids or airborne emissions
• Spanish Flu Epidemic - 1918-1919; killed 30
million people
– Ebola
• Transmitted by blood or body fluids
Toxicology and Human
Health
• Biological Hazards
– Types of Diseases
• Rabies
– Viral Disease
– Transmitted by dogs, skunks, raccoons
• AIDS
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HIV - kills body’s immune cells
Unprotected sex
Intravenous drug use
Blood transfusions
Toxicology and Human
Health
• Biological Hazards
– Types of Diseases
• AIDS Facts
– India has highest number of HIV-positive
people
– 1996 - 36 million people were infected with
HIV
– Heterosexual transmission accounts for 90%
of new HIV infections
Toxicology and Human
Health
• Biological Hazards
– Major Diseases in MDCs
• Epidemiological Transition
– Related to Demographic Transition
– Transmissible diseases supplanted by nontransmissible diseases
• Cardiovascular Disease (39%)
• Cancer (24%)
• Infectious Diseases (5%)
• Accidents (4%)
Toxicology and Human
Health
• Biological Hazards
– Sexually-Transmitted Diseases
• Exposure Pathways
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Sexual activity
Mother to infant during birth
Intravenous drug use
Infected blood
Toxicology and Human
Health
• Biological Hazards
– Sexually-Transmitted Diseases
• Bacterial STDs
– Chlamydia
– Gonorrhea
– Syphilis
• Viral STDs
– Genital herpes and warts
– Hepatitis B
– AIDS
Toxicology and Human
Health
• Risk Analysis
– Steps
• Risk Assessment
• Comparative Risk Analysis
• Risk Management
• Risk Communication
Toxicology and Human
Health
• Risk Analysis
– Risk Assessment - Identifying
hazards, estimating the probability
that each hazard will occur, and
estimating how many people may
suffer serious harm
Toxicology and Human
Health
• Risk Analysis
– Risk Management - determining
options about reducing or eliminating
risks
– Risk Communication - informing
decision makers and the public about
risks
Toxicology and Human
Health
• Risk Analysis
– Risk-Benefit Analysis - an estimate of
the short- and long-term risks and
benefits of using a particular product
or technology
Risk Analysis
Toxicology and Human
Health
• Risk Analysis
– Issues and Limitations
• Depends on toxicology assessments that
have scientific and economic limitations
• Who does the analysis?
• Who interprets the results of the
analysis?
• How are risk levels set?
• Goals of risk analysis?