Download QUESTION: Review

Ch 14
Environmental Health
and Toxicology
Part 2: Environmental Issues
and the Search for Solutions
PowerPoint® Slides prepared by
Jay Withgott and Heidi Marcum
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
This lecture will help you understand:
• Environmental health
hazards
• Toxicants in the
environment
• Hazards and their effects
• Risk assessment and risk
management
• Philosophical approaches to
risk
• Policy and regulation in the
U.S. and internationally
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Central Case: Lake Apopka alligators
• Alligators in Lake Apopka, Florida,
had reproductive problems
• Louis Guillette
• The lake had high levels of
agricultural runoff
• Chemical contaminants were
disrupting the endocrine systems of
alligators during egg development
• Because alligators and humans
share the same hormones,
chemicals can affect people, too
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There are many types of environmental
hazards
• Environmental health = assesses environmental factors
that influence human health and quality of life
- Natural and human-caused factors are both considered
• Physical hazards = occur naturally in our environment
- Earthquakes, volcanoes, fires, floods, droughts
- We can’t prevent them, but we can prepare for them
- We increase our vulnerability by deforesting slopes
(landslides), channelizing rivers (flooding), etc.
- We can reduce risk by better environmental choices
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Chemical and biological environmental
hazards
• Chemical = synthetic chemicals such as pesticides,
disinfectants, pharmaceuticals
- Harmful natural chemicals also exist
• Biological = result from ecological interactions
- Viruses, bacteria, and other pathogens
- Infectious (communicable, or transmissible) disease
= other species parasitize humans, fulfilling their
ecological roles
- We can’t avoid risk, but we can reduce the likelihood
of infection
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Cultural environmental hazards
• Cultural = result from the place we live, our
socioeconomic status, our occupation, our behavioral
choices
- Smoking, drug use, diet and nutrition, crime, mode of
transportation
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Four types of environmental hazards
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Disease is a major focus of environmental
health
• Despite our technology, disease
kills most of us
• Disease has a genetic and
environmental basis
- Cancer, heart disease,
respiratory disorders
- Poverty and poor hygiene can
foster illnesses
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Infectious diseases kill millions
• Infectious diseases kill 15
million people per year
- Half of all deaths in
developing countries
- Developed countries
have better hygiene,
access to medicine, and
money
• Vector = an organism that
transfers pathogens to a
host
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Many diseases are increasing
• Tuberculosis, acquired
immunodeficiency syndrome
(AIDS), and the West Nile
virus
• Our mobility spreads diseases
• Diseases are evolving
resistance to antibiotics
• Climate change will expand
the range of diseases
• To predict and prevent
diseases, experts deal with
complicated interrelationships
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Infectious disease accounts for
________% of deaths globally.
26
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Environmental health hazards exist
indoors
• Radon = a highly toxic, radioactive
gas that is colorless and undetectable
- Can build up in basements
• Lead poisoning = from lead pipes
- Damages organs; causes learning
problems, behavior abnormalities,
and death
• Asbestos = insulates, muffles sounds,
and resists fire
- Asbestosis = scarred lungs may
cease to function
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Toxicology is the study of poisonous
substances
• Toxicology = the study of the effects of poisonous
substances on humans and other organisms
• Toxicity = the degree of harm a toxicant can
cause
- “The dose makes the poison” = toxicity
depends on the combined effect of the chemical
and its quantity
- Analogous to pathogenicity or virulence = the
degree of harm of biological hazards that spread
disease
• Toxicant = any toxic agent
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Paracelsus
“All substances are poisons: there is
none which is not a poison. The right
dose differentiates a poison and a
remedy.”
• Paracelsus (1493-1541)
• Swiss German Renaissance physician, botanist,
alchemist, astrologer, and general occultist. He
founded the discipline of Toxicology.
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Environmental toxicology
• Deals with toxic substances that come from or are
discharged into the environment
• Studies the health effects on humans, other
animals, and ecosystems
- Focus mainly on humans, using other animals
as test subjects
- Can serve as indicators of health threats
• Don’t forget, chemicals have given us our high
standard of living
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Toxic agents in the environment
• The environment contains
countless natural chemicals
that may pose health risks
• But, synthetic chemicals are
also in our environment
- Every human carries
traces of industrial
chemicals
80% of U.S. streams contain at least trace amounts of 83
wastewater contaminants
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Very few chemicals have been thoroughly
tested
• 100,000 chemicals are on the market today
- 72,000 industrial
- 8,700 food additives
- 2,000 new chemicals introduced per year
• We don’t know the effects, if any, they have
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NY Times Article
In its history, the E.P.A. has mandated safety testing
for only a small percentage of the 85,000 industrial
chemicals available for use today.
And once chemicals are in use, the burden on the
E.P.A. is so high that it has succeeded in banning or
restricting only five substances, and often only in
specific applications: polychlorinated biphenyls,
dioxin, hexavalent chromium, asbestos and
chlorofluorocarbons.
http://www.nytimes.com/2013/04/14/sunday-review/think-those-chemicals-have-beentested.html?_r=0
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Silent Spring began public debate over
chemicals
• Rachel Carson published Silent Spring in 1962
- Brought together studies to show DDT risks to people,
wildlife, and ecosystems
- In the 1960s, pesticides were mostly untested and were
sprayed over public areas, assuming they would do no
harm
• The book generated significant social change
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Types of toxicants
• Carcinogens = cause cancer
• Mutagens = cause DNA mutations
- Can lead to severe problems,
including cancer
• Teratogens = cause birth defects
• Allergens = overactivate the immune
system
• Neurotoxins = assault the nervous
system
• Endocrine disruptors = interfere
with the endocrine (hormone) system
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What was the significance of the Yaqui
Valley, Mexico, study?
Found that pesticides caused neurological effects in children
that affected their learning abilities.
Video (5 min):
http://www.pbslearningmedia.or
g/resource/envh10.sci.life.eco.p
esticidestudy/the-effects-ofpesticides-on-children/
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The Heavy Metals
• Mercury/Methylmercury
• Lead
• Cadmium
• Arsenic
• Copper
• Zinc
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Heavy Metals
Minamata
Disease 3:12
http://www.y
outube.com/
watch?v=ihF
kyPv1jtU&fe
ature=fvwrel
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A recently recognized hazard
• Polybrominated diphenyl ethers (PBDEs) = has
fire-retardent properties
- Used in computers, televisions, plastics, and
furniture
- Persist and accumulate in living tissue
- Endocrine disruptors = compounds that
mimic hormones and interfere with the
functioning of animals’ endocrine (hormone)
systems
- Affect brain and nervous system development,
and may cause cancer
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Endocrine disruption may be widespread
• Theo Colburn wrote Our
Stolen Future in 1996
- Synthetic chemicals may
be altering the hormones
of animals
- This book integrated
scientific work from
various fields
- Shocked many readers
and brought criticism
from the chemical
industry
-
http://www.youtube.com/watch?v=jNz8yASPXoI&feature=related
•
Our stolen future 14 min Look back 15 years ago
•
http://www.youtube.com/watch?v=GtagXfTPMgk
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Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Evidence for hormone disruption
• Frogs also have gonadal
abnormalities
- Male frogs became
feminized from
atrazine concentrations
well below EPA
guidelines
• PCB-contaminated
human babies were born
weighing less, with
smaller heads
• Tyrone Hayes
Developmental Exposure in Children is different (17:48)
http://www.mnn.com/family/babies-pregnancy/blogs/watch-a-mom-and-ascientist-talk-toxins-and-babies
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Why are aquatic animals such as fish and
frogs especially good indicators of
pollution?
Most chemicals are water soluble so they enter these
organisms through drinking or skin absorption
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Male sperm counts are dropping
• Scientists attribute the shocking drop in men’s sperm counts to
endocrine disruptors
- The number and motility of sperm has dropped
50% since 1938
• Testicular cancer, undescended testicles, and genital birth
defects are also increasing
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Endocrine disruption research is
controversial
• Research results are uncertain, which is inherent in any
young field
• Negative findings pose economic threats to chemical
manufacturers
- Banning a top-selling chemical could cost a company
millions of dollars
- Bisphenol-A, found in plastics, can cause birth defects,
but the plastics industry protests that the chemical is
safe
• Studies reporting harm are publicly funded, but those
reporting no harm are industry funded
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What has the European Union's
experience with PBDE's shown?
If the toxin is removed from the environment,
concentrations in human tissues fall
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What caused penis abnormalities in
Taiwanese boys whose mothers used
contaminated cooking oil ?
PCB’s
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PCB (Polychlorinated biphenyl)
History of PCB 28 min (first 10)
https://docs.google.com/file/d/0Bz8IFlfcBZ0oWUNJ
M3QtZ3g1LWs/edit?pli=1
8 min PCB Harms in Environment
https://www.youtube.com/watch?v=oYD9L-aQcfw
• Widely used as dielectric and coolant fluids, for example
in electrical apparatus, cutting fluids for machining
operations, carbon paper and in heat transfer fluids
• A Persistant Organic Pollutant
• Endocrine Disruptor, Carcinogen, neurotoxin, immune
system disorders.
• Banned in U.S. in 1979 but still in the environment
because of persistence—it doesn’t break down
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What was the significance of the book Our
Stolen Future?
It focused on the impacts of endocrine-disrupting chemicals
on humans. It was first published in 1994.
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Toxins may concentrate in water
• Runoff carries toxins from large land areas to small
volumes of surface water
• Chemicals can leach into the soil
• Chemicals enter organisms through drinking or
absorption
- Aquatic organisms are effective pollution indicators
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The U.S. Geological Survey found that 80%
of U.S. streams contain at least trace
amounts of over how many
wastewater contaminants?
80
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Which organism was impacted by
infection from sewage run-off from cat
litter boxes from urban areas
Sea Otters
Toxoplasma gondii is best known for the threat it poses to the
fetuses of pregnant women exposed to the protozoan's eggs,
or oocysts, when cleaning their pets' litter boxes. Autopsies
have revealed that some otters have died from brain infections
caused by the parasite.
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Routes of chemical transport
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Describe these methods of Toxin
Movement
• leaching
• drift
• run-off
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Airborne toxicants travel widely
• Because chemicals can travel
by air, their effects can occur
far from the site of chemical
use
• Pesticide drift = airborne
transport of pesticides
• Synthetic chemical
contaminants are found
globally
- They appear in arctic polar
bears, Antarctic penguins,
and people living in
Greenland
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Some toxicants persist for a long time
• Toxins can degrade quickly and become harmless
- Or, they may remain unaltered and persist for decades
- Rates of degradation depends on temperature,
moisture, and sun exposure
• Persistent chemicals have the greatest potential for harm
• Breakdown products = toxicants degrade into simpler
products
- May be more or less harmful than the original
substance
- DDT degrades into DDE, which is also highly
persistent
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What kind of toxicant is known to have a
short persistence time?
Bt (Bacillus thuringiensis)
http://www.youtube.com/watch?
v=GbNypipCZK4 1:45
Bt resistance 3:50
http://www.youtube.com/watch?
v=TpSfR_OXVMc
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Toxicants can accumulate and biomagnify
• Some toxicants can be excreted
or metabolized
- Fat-soluble toxicants are
stored in fatty tissues
• Bioaccumulation = toxicants
build up in animal tissues
• Biomagnification = toxicants
concentrate in top predators
- Near extinction of peregrine
falcons and brown pelicans
Mercury Bioaccumualtion 2 min
http://vimeo.com/45969895
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Not all toxicants are synthetic
• Chemical toxicants also exist naturally and in our food
- Don’t assume natural chemicals are all healthy and
synthetic ones are all harmful
• Some scientists feel that natural toxicants dwarf our
intake of synthetic chemicals
- Natural defenses against toxins are effective against
synthetic ones, too
- Critics say natural toxins are more readily metabolized
and excreted, and synthetic chemicals persist and
accumulate
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Why are some threats to human
health unavoidable?
• They are wholly natural
and part of the natural
environment.
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How does Radon gas, a highly toxic
radioactive gas, get introduced
into homes?
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Toxoplasma
Toxoplasma in Cats and Mice
http://www.economist.com/node/16271339
http://www.opposingviews.com/i/health/addiction/catcrazy-feline-attraction-or-toxoplasmosis-part-2
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Wildlife studies
• Museum collections provide data from times before
synthetic chemicals were used
• Measurements from animals in the wild can be compared
to controlled experiments in the lab
• Scientists can first measure effects in the lab, then look
for correlations in the wild
• Conspicuous mortality events can trigger research
- Many sea otters died and washed ashore
- Research showed they died from parasites carried in
sewage runoff containing cat litter
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Human studies
• Case histories = studying sickened individuals directly
- Autopsies
- Don’t tell about future risks
• Epidemiology = large-scale comparisons between groups
of people
- Studies between exposed and unexposed people last for
years
- Yield accurate predictions about risk
• Animals are used as test subjects
- Some people object to animal research
- New techniques (human cell cultures, bacteria, etc.)
may replace some live-animal testing
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Why is examining case studies not
the best way to assess risk of
toxicants for human populations?
• Don’t show the effects of toxicants that build up over
time to cause problems
• Tell little about probability or risk such as how many
deaths might be expected in a population due to a
particular cause.
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Case Studies
• Analysis and observation of individuals
• Tell little about effects of rare hazards, new synthetic
chemicals, low environmental exposure, minor long term
effects
• Tell little about probability and risk
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Epidemiological Study
• Identifies statistical correlations found in large samples of
people. (Like a Natural Experiment)
• Tells probability and risk
• Does not show actual cause and effect
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Animal Testing (Animal Models)
• Manipulated experiment that identifies LD 50 and ED 50
• Shows cause and effect
• Assumes similar reactions between animals and humans
(relies on evolutionary history)
• Ethical questions
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What kind of study is this?
Baseline
body
mass
index*
Number of
PersonCrude
incident cases of
years
incidence
colon cancer
of follow up rate/100,000
PY
<22
28
53,475
52.36
22 - <24
41
38,919
105.35
24 - <26
36
36,610
98.33
26 - <28
40
32,635
122.57
28 - <30
35
21,122
165.70
30+
42
34,904
120.33
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What kind of study is this?
My grandpa has smoked a pack of cigarettes a day since he
was a teenager and has been healthy all his life. There are
no health risks associated with smoking long term.
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What kind of study is this?
Back problems in employees in Cell phone
manufacturing
Age
Persons
cases
Rate
25-39
1000
2
.002
40-55
700
25
.037
55+
50
15
.300
Total
1750
42
.024
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What kind of a study is this?
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Dose-response analysis
• Dose-response analysis = measuring how much effect a
toxicant produces at different doses
- Animal testing
- Dose = the amount of toxicant the test animal receives
- Response = the type or magnitude of negative effects of
the animal
- Dose-response curve = the plot of dose given against
response
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Dose response curves
• LD50/ED50= the amount of toxicant required to kill (affect)
50% of the subjects
• Threshold = the dose level where certain responses occur
- Organs can metabolize or excrete low doses of a toxicant
- Some toxicants show a J-shaped, U-shaped, or inverted
curve
• Scientists extrapolate downward from animal studies to
estimate the effect on humans
- Regulatory agencies set allowable limits well below
toxicity levels in lab studies
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Caffeine
• The minimum lethal dose of caffeine ever reported is
3,200 mg, administered intravenously.
• The LD50 of caffeine is estimated between 13 and 19
grams for oral administration for an average adult.
• So a person would have to drink over 100 cups of coffee
within a small time span to reach the LD50. (That
reminds me of the Futurama episode "300 big boys". )
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Individuals vary in their responses to
hazards
• Different people respond differently to hazards
- Affected by genetics, surroundings, etc.
- People in poor health are more sensitive
- Sensitivity also varies with sex, age, and weight
- Fetuses, infants, and young children are more
sensitive
• Standards for responses are set by the Environmental
Protection Agency (EPA)
- Often, standards are not low enough to protect
babies
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The type of exposure affects the response
• Acute exposure = high exposure for short periods
of time to a hazard
- Easy to recognize
- Stem from discrete events: ingestion, oil spills,
nuclear accident
• Chronic exposure = low exposure for long periods
of time to a hazard
- Hard to detect and diagnose
- Affects organs gradually: lung cancer, liver
damage
- Cause and effect may not be easily apparent
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Exposure Pathways
• Ingestion
• Inhalation
• Direct or External (Absorption through skin or
mucous membranes)
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Mixes may be more than the sum of their
parts
• We can’t determine the impact of mixed hazards
- They may act in ways that cannot be predicted from
the effects of each in isolation
• Synergistic effects = interactive impacts that are more
than or different from the simple sum of their
constituent effects
- Mixed toxicants can sum, cancel out, or multiply
each other’s effects
- New impacts may arise from mixing toxicants
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Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Risk assessment
• Risk = the probability that some harmful outcome will
result from a given action
- Exposure to environmental health threats doesn’t
automatically produce an effect
- Rather, it causes some probability (likelihood) of harm
• Probability entails
- Identity and strength of threat
- Chance and frequency that an organism will encounter
it
- Amount of exposure to the threat
- An organism’s sensitivity to the threat
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Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Perceiving risks
• Everything we do involves
some risk
• We try to minimize risk, but
we often misperceive it
- Flying versus driving
• We feel more at risk when we
cannot control a situation
- We fear nuclear power
and toxic waste, but not
smoking or overeating
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Analyzing risk quantitatively
• Risk assessment = the quantitative measurement of risk
and the comparison of risks involved in different
activities or substances
- It is a way of identifying and outlining problems
• Several steps:
- Scientific study of toxicity
- Assessing an individual or population’s likely extent
of exposure to the substance, including frequency,
concentrations, and length of exposure
• Studies are often performed by industry-associated
scientists, which may undermine the study’s objectivity
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Risk management
• Combines decisions and strategies to minimize risk
• Scientific assessments are considered with economic,
social, and political needs and values
• Developed nations have federal agencies to manage
risk
- The U.S. has the Centers for Disease Control
(CDC), the EPA, and the Food and Drug
Administration (FDA)
• Comparing costs and benefits is hard
- Benefits are economic and easy to calculate
- Health risks (costs) are hard-to-measure
probabilities of a few people being affected
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MSDS
Material Safety Data Sheets
• Risk Assessment
• Risk Management
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The process of risk management
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One approach to determining safety
• Innocent until proven guilty approach: the
government, scientists, and the public are required to
prove a product is dangerous
- Benefits: not slowing down technological
innovation and economic advancement
- Disadvantage: putting into wide use some
substances that may later on turn out to be
dangerous
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Another approach to determining safety
• Precautionary principle approach: Assume substances
are harmful until they are proven harmless. Product
manufacturers must prove a product is safe
- Identifies troublesome toxicants before they are
released
- But, this may impede the pace of technology and
economic advance
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Two approaches for determining safety
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Philosophy affects policy
• Different nations use different policies; most use a
mix between the “innocent until proven guilty”
principle and the precautionary principle
- Europe is shifting more towards the precautionary
principle
- Industries like the “innocent until proven guilty”
approach because it allows them to produce more
and make more money
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European Trends
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The EPA regulates many substances
• Federal agencies apportion responsibility for tracking and
regulating synthetic chemicals
- FDA: food, food additives, cosmetics, drugs, and medical
devices
- EPA: pesticides
- FIFRA
- TSCA
- Occupational Safety and Health Administration (OSHA):
workplace hazards
- CDC Centers for disease control sets policy for infectious
diseases
• Many public health and environmental advocates fear it isn’t
enough
- Many synthetic chemicals are not actually tested
- Only 10% have been tested for toxicity
- Fewer than 1% are government regulated
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What does the The Toxic Substances
Control Act (TSCA) regulate?
Industrial chemicals
Carried out by the EPA
Not…
• Drugs, pesticides, food additives,
cosmetics
• Catch 22 because the chemicals must be
shown to be toxic before more extensive
tests are done.
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Of the 80,000 chemicals that fall under the
TSCA ________% have been tested for toxicity
and ________ have been tested for endocrine,
nervous, or immune system damage.
10; almost none
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Which chemicals used in the U.S. are
not reviewed for safety?
Cosmetics
The agency charged with oversight of cosmetics, the
U.S. Food and Drug Administration (FDA), has no
authority to require pre-market safety assessment as it
does with drugs, so cosmetics are among the leastregulated products on the market.
The FDA does not review – nor does it have the
authority to regulate – what goes into cosmetics before
they are marketed for salon use and consumer use.
In fact, 89 percent of all ingredients in cosmetics have
not been evaluated for safety by any publicly
accountable institution.
The truth is, no one's minding the store when it comes
to shampoo, skin moisturizers, baby products, lipstick
or any other personal care product.
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Cosmetics
The FDA’s own Web site explains its limitations:
“FDA's legal authority over cosmetics is different from
other products regulated by the agency .... Cosmetic
products and ingredients are not subject to FDA premarket
approval authority, with the exception of color additives.”
Toxins in Cosmetics 4 min
http://www.youtube.com/watch?v=JAvnbOX8QX4
Toxic Cosmetics (Story of Stuff) 8 min
http://www.youtube.com/watch?v=pfq000AF1i8
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TSCA Info
• TSCA Introduction in 1975 Video 1:30
• http://www.youtube.com/watch?v=qA5sx6nsQw8
• Weakness of TSCA Video 1:30
• http://www.youtube.com/watch?v=_Tw_05E64Sg
•
• TSCA Reform video 2:21
• http://www.youtube.com/watch?v=S6KZarLA1E4
• Industry TSCA reform video 3min
• http://www.youtube.com/watch?v=FxGFwIgHx5c
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What is FIFRA?
The Federal Insecticide, Fungicide, and Rodenticide
Act and its later amendments charge the EPA with
registering new pesticides and regulating their sale,
use, and labeling.
This is not really designed to protect workers and
consumers but a “truth in advertising” law that
requires that the pesticide is actually effective. It
does not require a pesticide to be safe.
• FIFRA 5:30 min (doesn’t tell about health effects. Only registration regarding
use—not health effects)
• http://www.youtube.com/watch?v=4fgtEZW_ln8
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Match the toxicant with the regulatory
• Industrial chemicals
agency
- TSCA
• Drugs
-
FDA
• Pesticides
• FDA
• USDA
- FIFRA
• Food additives
- FDA
• FIFRA/EPA • Infectious disease protocols
• TSCA/EPA
• OSHA
• CDC
- CDC
• Cosmetics
- No Agency
• Job site safety
- OSHA
• Agricultural Practices (Meat and Nutriion)
- USDA
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Food Color
This review finds that all of the nine currently US-approved
dyes raise health concerns of varying degrees.
Red 3 causes cancer in animals, and there is evidence that
several other dyes also are carcinogenic.
Three dyes (Red 40, Yellow 5, and Yellow 6) have been
found to be contaminated with benzidine or other carcinogens.
At least four dyes (Blue 1, Red 40, Yellow 5, and Yellow 6)
cause hypersensitivity reactions. Numerous microbiological
and rodent studies of Yellow 5 were positive for genotoxicity.
Toxicity tests on two dyes (Citrus Red 2 and Orange B) also
suggest safety concerns, but Citrus Red 2 is used at low levels
and only on some Florida oranges and Orange B has not been
used for several years.
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Food Color
The inadequacy of much of the testing and the
evidence for carcinogenicity, genotoxicity, and
hypersensitivity, coupled with the fact that dyes do
not improve the safety or nutritional quality of
foods, indicates that all of the currently used dyes
should be removed from the food supply and
replaced, if at all, by safer colorings.
It is recommended that regulatory authorities
require better and independent toxicity testing,
exercise greater caution regarding continued
approval of these dyes, and in the future approve
only well-tested, safe dyes.
-National Institutes of Health http://www.ncbi.nlm.nih.gov/pubmed/23026007
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Hazards of Food Dyes
• Food Dyes 3:40
https://www.youtube.com/watch?v=611hJOb4M0g
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International regulation
• WHO (World Health Organization) A United Nations
organization that monitors and makes recommendations about
infectious diseases world wide.
• Nations address chemical pollution with international treaties
• Stockholm Convention on Persistent Organic Pollutants
(POPs) was ratified by 140 nations in 2004
- Ends the release of the 12 most dangerous POPs
• EU’s Registration, Evaluation, Authorization, and Restriction
of Chemicals (REACH) Program
- Aims to evaluate and restrict dangerous chemicals while
giving industries a streamlined regulatory system
- It will cost the chemical industry 2.8 – 5.2 billion euros
(U.S. $3.8 – 7.0 billion), but will save more than 10 times
that in health benefits
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What is the goal of the Stockholm
Convention?
• Identified POP’s (persistant organic pollutants) that
breakdown slowly in organisms and the environment and
easily bioaccumulate in tissues causing greater damage
than small exposure would indicate.
• Dirty Dozen: 12 of the worst POPs. Dioxin, Furans,
PCBs
• Sets international guidelines for phasing out these
chemicals.
Best slide show of POP’s (4 min) Dirty Dozen
/Stockholm Convention.
http://www.youtube.com/watch?v=pHDsigxcoWo
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Organochlorines and Organophosphates
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Dirty Dozen
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Conclusion
• International agreements represent a hopeful sign that
governments are working to protect society, wildlife,
and ecosystems from toxic chemicals and
environmental hazards
• Once all the scientific results are in, society’s
philosophical approach to risk management will
determine what policies are enacted
• A safe and happy future depends on knowing the
risks that some hazards pose and on replacing those
substances with safer ones
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QUESTION: Review
Which of the following is a biological hazard?
a)
b)
c)
d)
e)
Earthquake
Smoking
Virus
A pesticide
All are biological hazards
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QUESTION: Review
A “vector” is defined as …
a)
b)
c)
d)
A highly toxic, radioactive compound
An organism that transfers pathogens to a hose
A compound with fire-retardant properties
A compound that mimics natural substances
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QUESTION: Review
Toxicity is …
a)
b)
c)
d)
The study of the effects of poisonous substances
Any toxic agent
Any substance that causes environmental
degradation
The degree of harm a substance can cause
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QUESTION: Review
A “teratogen” causes…?
a)
b)
c)
d)
Cancer
Mutations
Birth defects
Problems in the hormonal system
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QUESTION: Review
Why is research into endocrine disrupters controversial?
a) Negative findings threaten the industry’s
economics
b) Research is still only beginning
c) Much research is funded by industry
d) All of these are reasons why research is
controversial
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QUESTION: Review
A human-based study that compares a group of smokers to
non-smokers to determine the effects of smoking is …
a)
b)
c)
d)
An epidemiological study
A case study
Not likely to be funded
Not going to tell about future risks
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What did Louis Guillette find?
• Hormone mimics from pesticide runnoff that affect
alligator hatching rates and gonad abnormalities
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What did Tyrone Hayes find?
• Deformities and reproductive abnormalities in frogs due
to atrazine, the active ingredient in the best selling
herbicide, round-up.
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What unusual place have
synthetic pesticides been
found in high concentrations?
• uninhabited polar regions
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QUESTION: Interpreting Graphs and Data
Our perception, and the reality, of risk often do not match. Given
this graph (reality), and your knowledge of sources of anxiety
(perception), which statement is correct?
a) Smoking is very dangerous
and we are very anxious
about it
b) Smoking is not dangerous,
but we are very anxious
about it
c) Airplane accidents are
dangerous, and we are very
anxious about it
d) Airplane accidents are not
dangerous, but we are very
anxious about it
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QUESTION: Interpreting Graphs and Data
If the “low” dose = 5 units of a chemical, the “medium” dose = 10
units, and the “high” dose = 15 units, how much of the chemical is
required to kill 50% of the study population?
a)
b)
c)
d)
From The Science behind the Stories
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About 5 units
About 10 units
About 15 units
You can’t tell from the
graph
What was the contribution of
Rachel Carson?
• Wrote books that increased the awareness of the effect of
industrial chemicals on ecosystems and on humans.
• Documented the prevalence of synthetic chemicals in
animal and human tissues.
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Explain each of the Following with
examples.
• biomagnification
• bioaccumulation
• synergism
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Explain each with an example
• neurotoxins
• allergens
• teratogens
• hormones
• antibiotics
• Carcinogens
• Vectors
• radon
• Bisphenol-A
• Bt
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QUESTION: Viewpoints
Is it unethical for a country that has banned a chemical
to manufacture and export it to other countries?
a) Yes; if we won’t have it in the U.S., we
shouldn’t make it
b) Yes, but the money we get from selling it will
help our economy
c) No; let people decide what they want to do
d) No; in fact, chemicals should not be banned in
the U.S. either
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QUESTION: Viewpoints
Should the government follow the precautionary principle and
force industries to prove their products are safe?
a) Absolutely; it is up to industry to prove its chemicals are
safe
b) Maybe, if it is not too expensive
c) No; let the government and scientists prove a chemical is
dangerous before it is taken off the market
d) No, as long as the product makes money and jobs for the
industry, it should be allowed
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Chemicals
• Atrazine
• PCB
• BPA
• DDT
• Phthalates
• Lead
• PFOA
• Mercury
• PBDE
• Asbestos
• PCE-
• Thalidamide
• Glyphosate
• Organochlorides
• Organophosphates
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• “The problem with toxicology is not the practicing
toxicologists, but chemists who can detect, precisely,
toxicologically insignificant amounts of chemicals”
• Rene Truhaut, University of Paris (1909-1994)
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Here is a final concept worth considering.
• Current technology allows us to accurately measure trace
quantities of chemicals.
• Yet, the biological significance of the presence of these
extremely small amounts of these chemicals is sometimes not
clear (e.g., carcinogens).
• Just because a drug or environmental contaminant is
measurable, does that mean that it poses a threat?
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Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Food for thought…
• Many environmental contaminants (and even foodstuffs)
are considered differently by different scientific groups
and agencies with regard to their safety.
• It is, therefore, up to the “consumer” in many cases to
make a judgment call as to how much exposure is
reasonable, based on available information. This concept
is related to RISK ASSESSMENT.
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