Download Understanding Our Environment

Environmental Health and Toxicology
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Reflection
What problems are unique to each
habitat?
What problems are common to each
habitat?
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Outline
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Environmental Health
 Infectious and Emergent Diseases
 Antibiotics and Pesticide Resistance
Toxicology
Movement, Distribution, and Fate of Toxins
Minimizing Toxic Effects
Measuring Toxicity
Risk Assessment
Establishing Public Policy
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ENVIRONMENTAL HEALTH
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Health - A state of complete physical, mental,
and social well-being.
Disease - A deleterious change in the body’s
condition in response to an environmental
factor.
 Diet and nutrition, infectious agents, toxic
chemicals, physical factors, and
psychological stress all play roles in
morbidity (illness) and mortality (death).
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Environmental Health Risks
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Global Disease Burden
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WHO reports communicable diseases are
responsible for nearly half of all 1.4 billion
DALY’s (disability adjusted life years) lost
each year.
 About 90% of all DALY losses occur in
developing world where one-tenth of all
health care dollars are spent.
- Malnutrition exacerbates many diseases.
 By 2020, heart disease may become
leading source of disability and
disease worldwide.
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Recent Outbreaks of Infectious Diseases
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Infectious Diseases
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For most of human history, the greatest health
threats have been pathogenic organisms,
accidents or violence.
 Communicable diseases are still
responsible for about 1.3 of all diseaserelated deaths.
- Majority in countries with poor nutrition,
sanitation, and vaccination programs.
 Malaria is a major disease in tropical
areas.
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Emergent Diseases
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An emergent disease is one never known
before, or has been absent for at least 20
years.
 An important factor in the spread of many
diseases is the speed and frequency of
modern travel.
- SARS
- West Nile Virus
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Funding Health Care
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Heaviest burden of illness borne by poorest
people who cannot afford a healthy
environment or adequate health care.
 WHO estimates 90% of all disease burden
occurs in developing countries where less
than 10% of all health care dollars are
spent.
- Worldwide, only 2% of people with AIDS
have access to modern medicines.
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Ecological Diseases
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Domestic animals and wildlife also
experience sudden and widespread
epidemics.
 Distemper in seals in western Europe.
 Chronic Wasting Disease in deer and elk in
North America.
 Sudden Oak Death Syndrome in
California.
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Antibiotic and Pesticide Resistance
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Protozoan parasite (Plasmodium) that
causes malaria is now resistant to most
antibiotics, while the mosquitoes that
transmit it have developed resistance to
many insecticides.
 Short life spans.
- Speeds up natural selection and
evolution.
 Human tendency to overuse pesticides
and antibiotics.
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Antibiotic Use
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At least half of the 100 million antibiotic
doses prescribed in the US every year are
unnecessary or are the wrong drug.
Many people do not finish full-course.
More than half of all antibiotics manufactured
in the US are routinely fed to farm animals to
stimulate weight gain.
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Antibiotic Resistance
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Toxicology
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Dangerous chemicals are divided into two
broad categories:
 Toxic - Poisonous
- Can be general or very specific. Often
harmful even in dilute concentrations.
 Hazardous - Dangerous
- Flammable, explosive, irritant, acid,
caustic.
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Toxic Chemicals
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Allergens - Substances that activate the
immune system.
 Antigens - Allergens that are recognized as
foreign by white blood cells and stimulate
the production of specific antibodies.
- Other allergens act indirectly by binding
to other materials so they become
antigenic.
 Sick Building Syndrome
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Toxic Chemicals
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Endocrine Disrupters disrupt normal hormone
functions.
 Thyroxine – PCB’s interfere with this and cause
the body to excrete thyroxine from the serum
 Insulin – Valproate, a seizure medication, can
disrupt insulin production in teenaged girls
 Adrenalin
 Endorphins
 Androgens – phthalates suppress testosterone in
male fetuses, causing ASD; DDT is also found to
do this
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Steroid Hormone Action
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Toxic Chemicals
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Neurotoxins - Metabolic poisons that
specifically attack nerve cells.
 Different types act in different ways.
- Heavy Metals kill nerve cells.
- Anesthetics and Chlorinated
Hydrocarbons disrupt nerve cell
membranes.
- Organophosphates and Carbamates
inhibit signal transmission between nerve
cells.
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Toxic Chemicals
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Mutagens - Agents that damage or alter
genetic material.
 Radiation
Teratogens - Specifically cause abnormalities
during embryonic growth and development.
 Alcohol - Fetal Alcohol Syndrome
Carcinogens - Substances that cause cancer.
 Cigarette smoke
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Diet
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Sixty-percent of all U.S. adults are now
considered overweight.
 Estimated 1 billion worldwide.
U.S. Centers for Disease Control warn one in
three U.S. children are at risk of becoming
diabetic.
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MOVEMENT, DISTRIBUTION,
AND FATE OF TOXINS
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Solubility - One of most important
characteristics in determining the movement of
a toxin.
Chemicals are divided into two major groups:
- Those that dissolve more readily in water.
- Those that dissolve more readily in oil.
 Water soluble compounds move rapidly
through the environment, and have ready
access to most human cells.
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Exposure and Susceptibility
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Airborne toxins generally cause more ill
health than any other exposure.
 Lining of lungs easily absorbs toxins.
Largest toxin exposure reported in industrial
settings.
Condition of organism and timing of
exposure also have strong influences on
toxicity.
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Exposure Routes
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Bioaccumulation and Biomagnification
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Cells have special mechanisms for
Bioaccumulation - Selective absorption and
storage.
 Dilute toxins in the environment can build
to dangerous levels inside cells and
tissues.
Biomagnification - Toxic burden of a large
number of organisms at a lower trophic level
is accumulated and concentrated by a
predator at a higher trophic level.
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Bioaccumulation and Biomagnification
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Persistence
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Some chemical compounds are very
unstable and degrade rapidly under most
conditions, thus their concentrations decline
quickly after release.
Others are more persistent.
 Stability can cause problems as toxic
effects may be stored for long period of
time and spread to unintended victims.
- (DDT)
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Persistence
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Persistent Organic Pollutants (POP’s)
 Polybrominated diphenyl ethers (PDBE)
 Perfluorooctane sulfonate (PFOS) and
Perfluorooctanic acid (PFOA).
 Phthalates
 Bisphenol A (BPA)
 Atrazine
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Chemical Interactions
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Antagonistic Reaction - One material
interferes with the effects, or stimulates the
breakdown, of other chemicals.
Additive Reaction - Effects of each chemical
are added to one another.
Synergistic Reaction - One substance
exacerbates the effect of the other.
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MECHANISMS FOR MINIMIZING
TOXIC EFFECTS
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Every material can be poisonous under
certain conditions.
 Most chemicals have a safe threshold
under which their effects are insignificant.
Metabolic Degradation
 In mammals, the liver is the primary site of
detoxification of both natural and
introduced poisons.
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Excretion and Repair
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Effects of waste products and environmental
toxins reduced by eliminating via excretion.
 Breathing
 Kidneys
- Urine
Tissues and organs often have mechanisms
for damage repair.
 Any irritating agent can be potentially
carcinogenic.
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MEASURING TOXICITY
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Animal Testing
 Most commonly used and widely accepted
toxicity test is to expose a population of
laboratory animals to measured doses of
specific toxins.
- Sensitivity differences pose a problem.
 Dose Response Curves
 LD50 - Dose at which 50% of the test
population is sensitive.
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Toxicity Ratings
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Moderate toxin takes about (1) g/kg of body
weight to produce a lethal dose.
 Very toxic materials require about 10% of
that amount.
- Extremely toxic materials require 1% of
that amount.
 Supertoxic chemicals can be lethal in
a dose of a few micrograms.
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Toxicity Ratings
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Many carcinogens, mutagens, and
teratogens are dangerous at levels far below
their direct toxic effect because abnormal cell
growth exerts a form of biological
amplification.
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Coalition for Consumer Information on Cosmetics
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By 1996 "cruelty free" shopping had become so popular as
to become confusing, sometimes misleading and ultimately
frustrating. Companies had begun designing their own
bunny logos, abiding by their own definition of "cruelty free"
or "animal friendly" without the participation of animal
protection groups.
In response, eight national animal protection groups banded
together to form the Coalition for Consumer Information on
Cosmetics (CCIC). The CCIC promotes a single
comprehensive standard and an internationally recognized
"leaping bunny" logo. We are working with companies to
help make shopping for animal-friendly products easier and
more trustworthy.
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Why does my bottle say "Not tested on animals," but the company is
not listed in the CCIC Shopping Guide?
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You may be aware that many products claiming to be
"cruelty free" or "not tested on animals" actually contain
ingredients that are tested on animals.
The alleged "cruelty free" claim often refers to the final
product; however, the majority of animal testing occurs
through the supply chain and therefore these products
actually contain ingredients tested on animals.
Similarly, some companies state that "we" do not test on
animals, when in fact they merely contract "someone else"
to do the testing.
These kinds of labels and claims are often confusing to
consumers.
Without an assurance from a company through the CCIC
certification program, we are unable to confirm its animal
testing policy or its labeling claims. However, we’re happy to
work with any company to get it on board!
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Skin Deep has the dish on cosmetics!
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The Environmental Working Group
Specializes in environmental investigations
Our team of scientists, engineers, policy experts, lawyers
and computer programmers pores over government data,
legal documents, scientific studies and our own laboratory
tests to expose threats to your health and the environment,
and to find solutions.
Our research brings to light unsettling facts that you have a
right to know. It shames and shakes up polluters and their
lobbyists. It rattles politicians and shapes policy. It
persuades bureaucracies to rethink science and strengthen
regulation. It provides practical information you can use to
protect your family and community.
http://www.ewg.org/reports/skindeep2/
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Acute versus Chronic Doses and Effects
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Acute Effects - Caused by a single exposure
and result in an immediate health problem.
Chronic Effects - Long-lasting. Can be result
of single large dose or repeated smaller
doses.
 Very difficult to assess specific health
effects due to other factors.
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RISK ASSESSMENT AND ACCEPTANCE
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Risk - Possibility of suffering harm or loss.
Risk Assessment - Scientific process of
estimating the threat that particular hazards
pose to human health.
 Risk Identification
 Dose Response Assessment
 Exposure Appraisal
 Risk Characterization
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Understanding Risks
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Factors influencing risk perception:
 Rating risks based on agendas.
 Most people have trouble with statistics.
 Personal experiences can be misleading.
 We have an exaggerated view of our
abilities to control our fate.
 News media sensationalizes rare events.
 Irrational fears lead to overestimation of
certain dangers.
- Fear of the unknown.
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Accepting Risks
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Most people will tolerate a higher probability
of occurrence of an event if the harm caused
by that event is low.
 Harm of greater severity is acceptable only
at low levels of frequency.
- EPA generally assumes 1 / 1 million is
acceptable risk for environmental
hazards.
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ESTABLISHING PUBLIC POLICY
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It is difficult to separate the effects of multiple
hazards and evaluate their risks accurately,
especially when exposures are near the
threshold of measurement and response.
 May not be reasonable to mandate
protection, no matter how small the risk,
from every potentially harmful contaminant
in our environment.
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TSCA of 1976
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The Toxic Substances Control Act (TSCA) of
1976 was enacted by Congress to give EPA
the ability to track the 75,000 industrial
chemicals currently produced or imported
into the United States. EPA repeatedly
screens these chemicals and can require
reporting or testing of those that may pose
an environmental or human-health hazard.
EPA can ban the manufacture and import of
those chemicals that pose an unreasonable
risk.
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SDWA of 1974
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Safe Drinking Water Act of 1974 authorizes the United
States Environmental Protection Agency (US EPA) to set
national health-based standards for drinking water to protect
against both naturally-occurring and man-made
contaminants that may be found in drinking water. US EPA,
states, and water systems then work together to make sure
that these standards are met.
number of threats to drinking water: improperly disposed of
chemicals; animal wastes; pesticides; human wastes;
wastes injected deep underground; and naturally-occurring
substances can all contaminate drinking water. Likewise,
drinking water that is not properly treated or disinfected, or
which travels through an improperly maintained distribution
system, may also pose a health risk.
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FQPA of 1996
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Food Quality Protection Act of 1996
Requires EPA to consider all non-occupational sources of exposure,
including drinking water, and exposure to other pesticides with a
common mechanism of toxicity when setting tolerances.
Requires an explicit determination that tolerances are safe for children
Requires distribution of a brochure in grocery stores on the health
effects of pesticides, how to avoid risks, and which foods have
tolerances for pesticide residues based on benefits considerations.
Specifically recognizes a state's right to require warnings or labeling of
food that has been treated with pesticides, such as California's
Proposition 65.
Includes enhanced enforcement of pesticide residue standards by
allowing the Food and Drug Administration to impose civil penalties for
tolerance violations.
States may not set tolerance levels that differ from national levels unless
the state petitions EPA for exception
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OSHA 1970
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Congress passed the Occupational and
Safety Health Act to ensure worker and
workplace safety. Their Goal was to make
sure employers provide their workers a place
of employment free from recognized hazards
to safety and health, such as exposure to
toxic chemicals, excessive noise levels,
mechanical dangers, heat or cold stress, or
unsanitary conditions.
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FFDCA of 1983
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The United States Federal Food, Drug, and
Cosmetic Act (FD&C) is a set of laws
passed by Congress in 1938 giving authority
to the Food and Drug Administration to
oversee the safety of food, drugs, and
cosmetics. In 1968, the Electronic Product
Radiation Control DESI provisions were
added to the FD&C. The act was amended
by the FDA Modernization Act of 1997.
http://en.wikipedia.org/wiki/Federal_Food,_Dr
ug,_and_Cosmetic_Act
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Red M&Ms,
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There were no red colored M&Ms from 1976
to 1987.
Red dye #2 was attributed to causing cancer
Public hysteria demanded that The Mars
Corp. remove red M&Ms from the M&M
lineup
currently contain Allura red AC (FD&C Red
#40)
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Summary
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Environmental Health
 Infectious and Emergent Diseases
 Antibiotics and Pesticide Resistance
Toxicology
Movement, Distribution, and Fate of Toxins
Minimizing Toxic Effects
Measuring Toxicity
Risk Assessment
Establishing Public Policy
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