Transcript Environmental Health, Pollution and Toxicology

Environmental Health,
Pollution and
Toxicology
Unit 5: AP Environmental Science (Chapter 15)
If it’s natural, does that mean it’s
always good?
• Disease results from an imbalance between an
organism and it’s environment
• The same things that can cause disease can be
beneficial to an organism
• Environmental factors determine the
prevalence and diversity of disease infections
What determines your chances
of getting a disease?
• Physical Environment
• Biological Environment
• Lifestyle
• Genetics
Terminology
Morbidity: having a disease
Mortality: death
Pathogen: disease causing
organism
Vector: transport system for
pathogens
Terminology
Pollution: introduces harmful materials or produces
harmful conditions to the environment
- introduced through a) Point Sources
b) Area Sources (Non-point)
c) Mobile Sources
d) Fugitive Sources
Contamination: making something unfit for a
particular use through the introduction of
undesirable material
Terminology
Toxicology: the science that studies chemicals that
should be toxic
Carcinogen: a type of toxin that increases the risk of
cancer
• Malignant, Benign, Metastasis
Synergism: the interaction of different substances
resulting in a total effect greater than the sum of
the effects of the separate sources (multiplies
effect)
• Antagonistic interactions reduce effects
Measuring Pollutants
• Measuring depends on the substance
• Common Units - can be mass/mass; or
mass/volume etc. Make sure you are
comparing similar units
• ppm: Parts per million
• ppb: Parts per billion
• Micrograms per cubic meter (measures air)
Categories of Pollutants
Infectious Agents, called pathogens –spread through
the interactions between people, food, air, water, soil
• Allergens; infectious bacteria, protozoans, viruses
•
(Examples: Legionnaires disease; salmonella; Anthrax,
e-coli, cholera)
Toxic Heavy Metals – metals with high atomic weights
• Body Burden – amount of metal we have in our body
•
(Examples: Mercury, Cadmium, Nickel, Lead, Arsenic,
Selenium)
Categories of Pollutants
Additional Pollutant Sources:
• Radiation
• Thermal Pollution
• Particulates
• Asbestos
• Electromagnetic Fields
• Noise Pollution
• Voluntary Exposure
Toxic Heavy Metals
• Travel through toxic
pathways
(Atmosphere land
water sediment)
• Biomagnification: the
accumulation or
increase in
concentration of a
substance in living
tissue as it moves
through a food web.
Toxic Pathway for Mercury
Organic Compounds
• Composed of carbon
• Synthetic Organic Compounds: used in
industrial processes
• Use in: pharmaceuticals, food additives,
pest control
• Over 20 million produced
• New ones appearing at about 1 million per
year
Organic Compounds
• Persistent Organic Pollutants: Synthetic organic
compounds often containing chlorine developed
in higher numbers around the same time as the
Green Revolution
• Do not break down easily
• Soluble in fat (allowing them to be absorbed in
living tissue)
• Easily transported by wind, water or sediments
• Examples: Aldrin, DDT, PCB’s, Dioxins
Organic Compounds
• Hormonally Active Agents: Chemicals in the
environment able to cause reproductive and
developmental abnormalities in animals
Thermal Pollution
• Occurs when heat released into water or air produces
undesirable effects
• Major heat pollution sources are electrical power
plants that use steam generators
• Warm water holds less oxygen
Asbestos
• Set of six minerals that form small,
fibrous strands
• Used in fire prevention and insulation
• Dangerous carcinogen if inhaled
Electromagnetic Fields
• Magnetic fields transmitted by
electric motors, transmission
lines for utilities, and electrical
appliances
• Strength of fields decreases
with distance
• Some studies show an
increased risk, especially in
children, of developing cancer
with higher exposure to
magnetic fields(1.5-3x higher
than low exposures)
Voluntary Exposure
• Personal choice to consume or interact with
toxic material knowing the risks involved
• Smoking
• Drinking
• Substance abuse
• Job hazards
• Habitat
General Effects of Pollutants
• Changes in Abundance
• Changes in Distribution
• Changes in Birth Rates
• Changes in Death Rates
• Changes in Growth Rates
• “All substances are poisons: there is none which
is not a poison. The right dose differentiates a
poison and a remedy." Paracelsus (1493-1541)
General Effects of Pollutants
• There are 500 synthetic organic chemicals in our body burden
today that did not exist before 1920
• Environmental factors like malnutrition, smoking, cooking
fires, skin cancer, exposure to chemicals contribute to 40% of
the world’s annual deaths
RISK
Modern
Traditional
TIME
Worldwide Diseases
1. Acute Respiratory Infection Deaths
• 3.9 million/year, 2.5 million children
2. AIDS
• 3 million/year, most are young adults
3. Diarrheal Diseases
• 2.1 million/year, 1.9 million/year under the age of 5
4.
5.
6.
7.
Tuberculosis 1.6 million/year
Malaria 1 million/year
Hepatitis B
1 million/year
Measles 800,000/year, mostly under the age of 5 and increasing
• Anti-viral drugs are widely used although few are effective and there
are high chances of side effects. Vaccines are still the best method of
treatment for viral diseases.
Worldwide Cases of Death
Source
Annual Deaths
Poverty/Malnutrition
10 million
Tobacco
4 million
Pneumonia/Flu
3.9 million
Air Pollution
3 million
AIDS
3 million
Diarrheal
2.1 million
Tuberculosis
1.6 million
Malaria
1.1 million
Work Related
1.1 million
Hepatitis B
1 million
Chemical Hazards
• A toxic chemical can cause temporary or
permanent harm or death.
• Mutagens are chemicals or forms of radiation
that cause or increase the frequency of
mutations in DNA.
• Teratogens are chemicals that cause harm or
birth defects to a fetus or embryo.
• Carcinogens are chemicals or types of
radiation that can cause or promote cancer.
Disease Sources
Carcinogen Source
Smoking
Diet
Occupational Exposures
Inherited Genetics
Percentage of all cancers
30-40%
20-30%
10-20%
10-20%
• In general transmissible diseases have dropped
since the 1950’s but non-transmissible diseases
have risen
Chemical Hazards
• A hazardous chemical can harm humans or other
animals because it:
• Is flammable
• Is explosive
• An irritant
• Interferes with oxygen uptake
• Induce allergic reactions.
Chemical Hazards
• Long-term exposure to some chemicals at low
doses may disrupt the body’s:
• Immune system: specialized cells and tissues that
protect the body against disease and harmful
substances.
• Nervous system: brain, spinal cord, and peripheral
nerves.
• Endocrine system: complex network of glands that
release minute amounts of hormones into the
bloodstream.
Chemical Hazards
• Individual cells have
enzymes to repair damaged
DNA and protein
• Some cells grow fast enough
to replace damaged cells
while other have a longer
lifespan that would not
repair the damage before
negative effects set in
Chemical Hazards
• Molecules of certain synthetic chemicals have
shapes similar to those of natural hormones and
can adversely affect the endocrine system.
Concept of Dose and Response
• The effect of a certain chemical on an individual
depends on the dose
• Individuals differ in their response to chemicals
Threshold Effects:
- the level below which effects are not observable
and above which effects become apparent
Therapeutic Index:
- ratio of the amount of a substance that is
effective compared to the amount that becomes
toxic (LD-50 : ED-50)
Dose and Response Curve
Dose and Response Curve
• ED-50 Effective Dose 50%: amount of a
substance to produce a specific effect on 50%
of a test sample of organisms. (This can be a
toxic or non-toxic effect)
• TD-50 Toxic Dose 50%:the dose that produces
a toxic effect in 50% of the population
• LD-50: Lethal Dose 50%: dose of toxin it takes
to kill 50% of the organisms
Dose and Response Curve
Ecological Gradients
• Changes in vegetation with distance from a toxic
source.
• Tolerance: The ability to resist or withstand
stress resulting from exposure to a pollutant or
harmful condition
• Behavioral tolerance teaches avoidance of the
stress
• Physiological tolerance comes from adaptation
to the stress or a genetic resistance to stresses
caused by a pollutant
Ecological Gradients
Acute and Chronic Effects
• Acute – occurs soon after
exposure to large doses
• Chronic- occur over
extended periods of time,
usually from low doses
of exposure
Effects of Exposure
• Factors determining the harm
caused by exposure to a
chemical include:
• The amount of exposure
(dose).
• The frequency of exposure.
• The person who is exposed.
• The effectiveness of the
body’s detoxification
systems.
• One’s genetic makeup.
Risk Assessment
• Risk – the possibility for harm (Exposure x Harm)
• Calculating this risk is called Risk Assessment
• 4 steps
1. Identification of the hazard
2. Dose-Response assessment
3. Exposure assessment
4. Risk characterization
United States Hazard Effects
Hazard
Shortens Life Span By:
Poverty
7-10 years
Born male
7-5 years
Smoking
6 years
Overweight (by 35%)
6 years
Single
5 years
Overweight (by 15%)
2 years
Spouse that smokes
1 year
Driving
7 months
Air pollution
5 months
Alcohol
5 months
Drug abuse
4 months
Flu
4 months
AIDS
3 months
Risk Assessment
• Under existing laws, most chemicals are
considered innocent until proven guilty, and
estimating their toxicity is difficult, uncertain,
and expensive.
• Federal and state governments do not regulate
about 99.5% of the commercially used
chemicals in the U.S.
Risk Assessment
• The U.S. Environmental Protection Agency
proposed that regulators should assume children
have 10 times the exposure risk of adults to
cancer-causing chemicals.
• Some health scientists contend that regulators
should assume a risk 100 times that of adults.
Risk Assessment
• Children are more susceptible to the effects of
toxic substances because:
• Children breathe more air, drink more water,
and eat more food per unit of body weight
than adults.
• They are exposed to toxins when they put their
fingers or other objects in their mouths.
• Children usually have less well-developed
immune systems and detoxification processes
than adults.
Precautionary Principle
• The idea that in spite of the fact that full scientific
certainty is often not available to prove cause
and effect, we should still take cost-effective
precautions to solve environmental problems
where there exists a threat of potentially serious
and/ or irreversible environmental damage
• Manufacturers contend that wide-spread
application of the precautionary principle would
make it too expensive to introduce new
chemicals and technologies.
Becoming Better at Risk Analysis
Risk Assessment
Risk Management
Hazard identification
Comparative risk analysis
What is the
hazard?
How does it compare
with other risks?
Risk reduction
Probability of risk
How likely is
the event?
How much should it
be reduced?
Risk reduction strategy
How will the risk
be reduced?
Consequences of risk
What is the
likely
damage?
Financial commitment
How much money
should be spent?
What is the good news?
• 99.1% of people each year do not die