Download Chapter 17_lecture Health

Human Health &
Environmental
Risk Goals
Identify the 3 categories of
human health risk
Know historical & emerging
infectious diseases
Name 5 major types of toxic
chemicals
Distinguish between doseresponse, retrospective &
prospective studies
What factors determine
chemical concentration in an
organism?
What factors go into risk
analysis?
3 categories of human health risks
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Physical
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Biological
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Chemical
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Natural disasters, U.V.
Rays, radioactivity
Diseases, parasites,
microorganisms
Naturally occurring,
arsenic or synthetic agent
orange
Leading causes of death
Biological Risks
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Infectious diseases- those caused by infectious
agents, known as pathogens.
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Examples: pneumonia and venereal diseases
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Chronic disease- slowly impairs the functioning of a
person’s body. Heart disease
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Acute diseases- rapidly impair the functioning of a
person’s body. Some cancers, some viruses
Leading health risks by World Health Organization
(WHO)
As a country becomes more developed, the
transition of risk…?
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Decrease due to?
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Income increasing
Adequate nutrition and healthcare
Historical Diseases
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Plague
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Malaria
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Tuberculosis
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Caused by bacteria
Yersinia pestis, carried by
fleas on rodents. Wiped out
about ¼ of the population
during the 1300’s
Protist that lives inside
mosquitos. 1 million under
5 die each year. Mosquito
netting and insecticide are
key to education.
Bacterial transmission of
Mycobacterium tuberculosis
2 million die each year.
There are now drug
resistant strains
Emergent Diseases
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HIV/AIDS
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Ebola
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Mad Cow Disease
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Bird Flu
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West Nile Virus
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Retro virus, genetically similar
to SIV, chimp virus. 33 million
humans are infected, 25 m
have died.
Caused by virus. High death
rate. No drugs for a cure.
Proteins called prions, alter
normal prions in the brain.
Similar effects to Alzheimer’s.
Eat infected cattle, sheep,
deer. 166 people died in 2009
in Britain
Avian influenza caused by
H5n1 virus. 400 infected by
2009
Caused by infected birdsmosquitos. Can infect humans
& cause inflammation of the
brain
How to combat Diseases
Low Income countries
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Education campaigns on disease
transmission
Improve nutrition, wider availability
of clean, drinking water.
Sanitation
High Income countries
Education on disease transmission
Promote healthier lifestyle choices
Increase physical activity
Balanced diet
Reduce tobacco use
Toxicology the study of chemical risks
Categories of toxins
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Neurotoxins- chemicals that disrupt the nervous system. Insecticides, lead,
mercury. Invertebrates become paralyzed, can’t get oxygen and die. Lead &
mercury can damage, kidneys, the brain and nervous system.
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Carcinogens- chemicals that cause cancer. If they damage genes they are called
mutagens. Examples, asbestos, radon, formaldehyde & tobacco
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Teratogens- chemicals that interfere with the normal development of embryos or
fetuses. Thalidomide used to prevent miscarriage in pregnant women caused
defects. Alcohol is the most common reduces fetal growth , brain & nerve damage.
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Allergens- chemicals that cause allergic reactions. Breathing, rash. Peanuts, dust,
milk , some drugs
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Endocrine disruptors- chemicals that interfere with the normal functioning of
hormones in an animal’s body. Hormones from animal meat, sewage. Fish &
amphibians are very susceptible to the effects of hormones.
Dose-Response Studies
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Expose animals or plants to different amounts of chemicals and
observe responses-mortality, behavior or reproduction. Usually last
1-4 days, so they are called acute studies.
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LD50- lethal dose that kills 50% of the individuals. What is the safe
dose for mice? Divide the LD50 value by 10=5.8/10=.58mg/dl
Values for humans are divided by 1,000. Why?
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Want the lower dose to ensure safety. What would be the safe dose
for a child? Divide by more than 1,000
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ED50- effective dose that causes 50% of the animals to display the
harmful but nonlethal effect
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LD50 on humans is not ethical, studies are done on model
organisms, mice, apes & extrapolated for a human.
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ED50 AKA sublethal effect what dose causes 50% to display
harmful, not lethal effect.
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Threshold dose at which an effect can be detected
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Toxic Substances Control Act of 1976 EPA has authority to
regulate chemicals. Pesticides are regulated Federal
Insecticide, Fungicide & Rodenticide Act of 1976. Cannot
cause unreasonable adverse effects on the environment.
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categories tested- birds, mammals, fish &
invertebrates.
Amphibians & reptiles are covered under the fish
grouping for water animals. Birds are used to
represent land amphibians & reptiles.
These animals most sensitive in the world.
If you know the sensitivity of the most sensitive
species in the group, then any regulations to
protect it would also protect the other species in
the group.
Epidemiology Studies
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Epidemiology investigate the causes of illness & disease in
human & wildlife populations. Two ways to conduct:
1. Retrospective look back into the past. Identify and
monitor those who have been exposed to potentially harmful
substances. Also, you would want to monitor those who
were not exposed. Monitoring can take years. (Bhopal,
India) video
Higher rates of respiratory symptoms and still births, genetic
abnormalities, infant mortality, kidney failure & learning
disabilities.
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2. Prospective Study monitor people & wildlife who might
become exposed to harmful substances in the future.
Cancer studies. May ask people to record their diet, tobacco
& alcohol use over many years.
Prospective studies are challenging since habits like tobacco
use can be associated with other risk factors.
Synergistic interactions- when two risks come together and
cause more harm that one would. For example, the health
impact of a carcinogen such as asbestos can be much higher if
an individual also smokes tobacco.
Studies on lead on children are often conducted this way.
Video on lead
Routes of Exposure
Remember the news report on NJ underground oil tanks?
Pompton Lakes contamination
Bioaccumulation
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Bisphenol A remember TED talk video. a chemical
used for hard plastics in toys, food containers, baby
bottles, water bottles. Studies show it may be
responsible for early puberty & increased cancer
risk.
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Bioaccumulation- an increased concentration of a
chemical within an organism over time
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Biomagnification increase in chemical
concentration in animal tissue as it moves up the
food chain.
Biomagnification
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Biomagnification- the
increase in a chemical
concentration in animal
tissues as the chemical moves
up the food chain.
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Fat soluble chemicals
accumulate in tissues. Often
found in benthic zone. PCB’s
polychlorinated biphenol
neurotoxin , carcinogen &
teratogen (electronics,
pesticides, paint, plastics),
Mercury, DDT.
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Water soluble chemicals
disperse in water easily.
Acids, salts, some metals
Why are children more susceptible?
• Immune system are still developing
• They take in more air, food & water per
unit of body weight than adults.
• Children put dirt, objects in their
mouths
• Their livers are not mature enough to
metabolize pollutants
• Pollutants can accumulate longer in
children
Persistence
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Persistence- how long a chemical remains in the
environment, often measured by its half life
Qualitative Risk Assessment
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Making a judgment of the relative risks of various
decisions
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Probability- the statistical likelihood of an event
occurring and the probability of that event causing
harm. Nuclear plant meltdown v car accident
Quantitative Risk Assessment
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Risk= probability of being exposed to hazard x
probability of being harmed if exposed.
Flying v peanut butter
Both are a 1 in a million chance
Risk Management
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3rd step in risk analysis.
Regulatory role.
Innocent until proven guilty principle-until scientific
data prove otherwise. U.S. Policy
Precautionary principle, take action to reduce or
remove hazard. European Union Policy
Risk Assessment of Polychlorinated
Biphenyl (PCB’s)
• Risk of eating contaminated fish is
higher than risk of drinking
contaminated water, & higher than
breathing contaminated air.
• Result, signs are posted on the Hudson
River not to consume fish.
• EPA believes a 1 in a million risk is an
acceptable level for hazards.
International Agreements
Stockholm Convention
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In 2001, a group of 127 nations gathered in Stockholm,
Sweden, to reach an agreement on restricting the global use of
some chemicals
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12 chemicals were to be banned, phased out, or reduced
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These include DDT, PCBs, and certain chemicals that are byproducts of manufacturing processes.
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REACH 2007, 27 European nations agreement on how to
regulate chemicals. Registration, Evaluation, Authorization, &
restriction of Chemicals. Embraces precautionary principle.
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Video harmful chemicals
DuPont & PFOS
• Wilbur Tennant and his farm-video
• Podcast-link to obesity