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11/14/12
Chapter 8 guide:
Outline:
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8.1 describe health & disease & how the global disease burden is now changing
8.2 summarize the principles of toxicology
8.3 discuss the movement, distribution, & fate of toxins in the environment
8.4 explain ways we evaluate toxicity & risk
8.5 relate how we establish health policy
8.1 Environmental health
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Global disease are decreasing such as infectious decease & while internal health
problems increase
Emergent diseases increases as we come into contact with new environments (sharing
germs)
Conservation medicine combines ecology with health care
Health- well-being of an individual mentally, socially & physically
Disease- impairment of body function mentally, socially & physically
Morbidity- illness
Mortality- death
Environmental health- external (outside) factors that causes diseases such as environment
& nature
The global disease burden is changing
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Although pollution is increasing on the brighter side there have been significant progress
in disease treatments
Disability- adjusted life years (DALYs)- measure of disease burden, premature deaths &
loss of healthy life cause of illness or disability
Chronic obstructive lung diseases (COPD)
Infectious & emergent diseases still kill millions of people
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Pathogens- disease-causing organisms
Protozoans- single-celled animals
Severe acute respiratory syndrome (SARS)
Emergent diseases- not previously learned or have been absent for 20years
Conservation medicine combines ecology & health care-
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Ecological diseases- suffering of new & devastating diseases (widespread epidemics)
Conservation medicine- understand how environmental threatens our well-being & those
organisms that live in nature & that we depend on for services
Resistance to drugs, antibiotics, & pesticides is increasing
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Diseases thought to be wiped out come back even stronger & insects or organisms that
carry them because of developing resistance to cures
Humans cause evolution to develop faster when trying to extinguish all pesticides with
harmful toxins
What would better health cost?
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Better health cost millions of dollars that’s why there are funds that provide donations to
developing countries
Africa has a hard time with affording health care & a healthy environment
8.2 Toxicology
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Many toxins harmful in weak liquid concentrations (billionth or trillionth causes
irreversible damages)
Toxins found in home in wide variety of products
Chemicals disrupt hormonal functions harmful in growth developments even in small
doses
Toxins- poisons
How do toxins affect us?
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Allergens- substances that activate the immune system
Antigens- recognized as foreign by white blood cells stimulate production antibodies
protects body foreign diseases
Sick building syndrome- poorly ventilated indoor air (causes headaches & allergies)
Endocrine disrupters- chemicals that disrupt hormonal functions
Neurotoxins- special class of metabolic poisons that specifically attack nerve cells
(neurons)
Mutagens- chemicals or radiation causes changes in genetic material (DNA)
Teratogens- factors or chemicals causes problems during pregnancy growth
Fetal alcohol syndrome- cluster of symptoms that happens throughout a child’s life
(behavior problems)
Carcinogens- substance cause cancer
Cancer- out of control cell growth that causes tumors (2nd leading cause of death)
How do diet influence health?-
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60% adults in U.S. are considered overweight (300,000 links to death)
Eating more causes health problem & type of food
Eat healthy & less saves people from obesity
8.3 movement, distribution, & fate of toxins
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Solubility & mobility determine where & when chemicals move through the environment
& in our bodies
Persistent materials can move concentrated toxic materials through food web to top
predators
Synergistic interactions increase effects of combined toxins far beyond any single
substance
Solubility & mobility determine where & when chemicals move
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Two chemical type dissolve in water or in oil (readily access to body cells)
Stays very long time in body
Exposure & susceptibility determine how we respond
Human breath more in any other activity such as eating etc. making them more prone to
toxins & death
Bioaccumulation & biomagnification increase concentrations of chemicals
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Bioaccumulation- selective absorption & storage of a great variety of molecules
Biomagnification- toxic burden on large # organisms lower trophic level then
concentrated in a predator in a higher trophic level
Persistence makes some materials a greater threat
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Substances that are resistant to degradation
Persistent organic pollutants (POPs)- top toxic concentration in top predators (humans,
bears, sharks, etc.)
Body burden- persistent toxins in our bodies (water, diets, & surroundings)
Chemicals interactions can increase toxicity
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Synergism- one substances makes the effects of another worst
Example smoking accelerates the cause of cancer
Metabolic degradation & excretion eliminate toxins
Toxins can come out of the body through waste
Repair mechanisms mend damage
Cells that are damaged regularly can repair damages although if frequently it may lose
that ability to repair
8.4 Toxicity & risk assessment
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Toxicology dose makes the poison, amount, timing, exposure determines response
Fear proportion but ignores hazards despite effects
Substances or factors disruption of developments at low doses
We usually test toxins on lab animals
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Testing population under controlled conditions
LD50- test whether 50% of the test population is sensitive
There is a wide range of toxicity
Toxics reside in food can even kill a mouse imagine what it’s doing to our bodies
Acute & chronic doses & effects differ
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Acute effects- single exposure to toxin & cause immediate health crisis
Chronic effects- cause of single dose toxic substances or continuously
Detectable levels aren’t always dangerous
Toxins are found scattered everywhere in food samplings (maybe insignifigant)
Low doses can have variable effects
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Either good or bad effects, helps or hurts you
Protects against cancer or causes health problems
Some symptoms can be erroneous
When a person describe how sick they are you begin to feel sick as well (no evidence
though)
Risk perception isn’t always rational
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Risk- possibility of suffering harm or loss
Risk assessment- process estimate hazards pose to human health
Risk acceptance depends on many factors
Weighing does the benefits outweigh the risks
8.5 establishing health policy
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Difficult evaluate multiple risks & benefits simultaneously
Setting health standards consider combined exposures, difference btwn chronic & acute
exposure
Precautionary exposure- show substance is not dangerous before they are introduced