Download Toxicology Notes

“All substances are poisons: there is none which is not a
poison. The right dose differentiates a poison and a
remedy." Paracelsus (1493-1541)
TOXICOLOGY
APES
CHAPTER 17
• Risk: probability of suffering harm from a hazard that
can cause injury, disease, death or economic loss or
damage
• Risk assessment: evaluate risk associated with a hazard
• Risk management: implement plan of action
• Cost-benefit analysis
• Risk-benefit analysis
• Biological, chemical, natural, cultural and lifestyle
hazards
• Hazard: anything that can cause injury, disease, or death to
humans; damage to personal or public property; deterioration
or destruction of environmental components
BIOLOGICAL HAZARDS
• Infectious disease (flu, malaria, TB)
• Caused by a pathogen (virus, bacteria, protists, fungi,
helminths--worms)
• Transmissible disease (measles, HIV)
• Non-transmissible disease (cancer, asthma, diabetes,
malnutrition)
• Not caused by pathogen
• Major concerns include flu, AIDS (HIV), Hepatitis B,
malaria and emergent diseases (West Nile, Ebola)
• 94% of all deaths attributed to infectious disease are from AIDS,
respiratory viruses, and diarrheal disease
BIOLOGICAL HAZARDS
• Factors that contribute to chronic diseases (heart
disease, diabetes, emphysema…) more prevalent in
developed nations
• High blood pressure, tobacco use, high blood glucose, obesity
• In developing countries chronic disease (respiratory and
diarrheal infections) risk factors include
• Unsafe sex, alcohol use, indoor smoke (cooking fires), unsafe
water, malnutrition
• Eliminate through infectious disease prevention,
education, vaccines, improving quality of life and
decreasing malnutrition
CHEMICAL HAZARDS
• Toxic chemical: can cause temporary or permanent harm or death
to humans or animals
• Top 5 include: arsenic, lead, mercury, vinyl chloride (plastics) and PCBs
• Neurotoxin: chemicals that disrupt the nervous system of animals
• Insecticide, lead, mercury
• Endocrine disruptor: interfere with normal hormone functioning
• Medications, atrazine, pesticides
• Carcinogen: promotes cancer
• Arsenic, benzene, formaldehyde, gamma and UV radiation, PCBs, radon,
tobacco smoke, vinyl chloride, asbestos
• Mutagen: increases frequency of mutations
• Teratogen: cause harm or birth defects to fetus/embryo
• Alcohol, benzene, formaldehyde, lead, mercury, PCBs, phalates, thalidomide,
vinyl chloride
EVALUATING CHEMICAL HAZARDS
• Toxicity: measure of the harmfulness of the product
• Dose: amount ingested, inhaled, or absorbed
• Response: damage to health, may be acute or chronic
• Depends on age, genetic makeup, solubility of compound
(water vs. oil) and persistence
• Dose-response Studies
• Tests on animals with measure doses of chemical
• Plot results of chemical tests to determine curve and lethal
doses
LD50
• Lethal dose 50: Amount of chemical that kills 50% of a test
population within 18 days.
• Varies depending on substance
• Determines if a new substance is more or less lethal than other
chemicals used
• Usually tested on rats…then extrapolated to humans
• Gives values for acute toxicity
• Lower LD50 = More toxic
ENVIRONMENTAL POLLUTANTS
• Pollution: the presence of a substance in the
environment that prevents the functioning of
natural processes and produces undesirable
environmental or health effects
• Increases with growing population and expanding use of
resources
• Effects can be aesthetic (not pretty), globalized or local
• Pollutant: any material that causes pollution
• Usually by-products of normal/essential activities
TOP ENVIRONMENTAL POLLUTANTS
• Asbestos
• Indoor air pollutant
• From ceiling tiles and pipe
insulation
• Impacts human health (lung
cancer, mesothelioma)
• CFCs
• Atmospheric air pollutant
• From air conditioners and
refrigerators
• Impacts ozone layer
(greenhouse gas)
• Carbon Monoxide (CO)
• Air pollutant (indoor/outdoor)
• From burning of fossil fuels
• Impacts atmosphere (weak
greenhouse gas) and human
health
• Carbon Dioxide (CO2)
• Air pollutant
(indoor/outdoor)
• From respiration, combustion
of organic material
• Impacts climate change
(greenhouse gas)
• Dioxins
• Soil/water pollutant
• From industrial processes
(by-product)
• Impacts endocrine/immune
system, toxic to animals,
bioaccumulation
• Disease Agents
• Water pollutant
• From animal/human waste
• Impacts…
TOP ENVIRONMENTAL POLLUTANTS
• Formaldehyde
• Indoor air pollutant
• From building materials, textiles,
furniture
• Impacts…
• Lead
• Air, soil, water pollutant
• From industry, gas, paint
• Plant/animal impacts
• Mercury
• Air, soil, water pollutant
• From combustion of coal,
burning, smelting
• Mutagenic impacts,
bioaccumulation
• Nox
• Air, water pollutant
• From combustion of fossil fuels
• Impacts air quality (smog),
acid rain, increase
tropospheric ozone
• Oil
• Water/soil pollutant
• Natural source, surface runoff,
spills
• Impacts water quality,
aquatic organisms (toxic)
• Oxygen Demanding Waste
• Water pollutant
• From sewage, industry,
agriculture
• Impacts dissolve oxygen in
water (anoxic)
TOP ENVIRONMENTAL POLLUTANTS
• Ozone
• Air pollutant
• From photochemical reaction
with NOx and VOCs
• Impacts plants, respiratory
irritant (asthma)
• Particulates
• Air pollutant
• From soot, dust, soil, smoke,
industry
• Impacts photosynthesis, air
quality
• Pesticides
• Air, Soil, water pollutant
• From agriculture, golf courses,
urban runoff
• Impacts plant/animals, toxic,
bioaccumulates
• Phosphates
• Water pollutant
• From fertilizer, sewage
• Impacts water quality
(eutrophication)
• Radon
• Indoor air pollutant
• From radioactive decay of
uranium
• Impacts human health (lung
cancer)
• Sulfur Dioxide (SO2)
• Air pollutant
• From combustion of coal
• Impacts air quality (acid rain),
forms smog
LEGISLATION INVOLVED IN
MANAGING TOXINS
•
FIFRA (Federal Insecticide, Fungicide, Rodenticide Act)—1910 (1972)
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Clean Air Act--1970
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Gave the 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 and
environmental or human-health hazard.
Stockholm Convention--2001
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establishes and maintains goals and standards for U.S. water quality and purity
eliminate the discharge of pollutants into rivers, lakes, streams and other waterways
Toxic Substances Control Act—1976
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to establish air quality standards designed to minimize the air pollution found most harmful to human health.
Six pollutants were specifically targeted--particulate matter, sulfur dioxide (SO2), carbon monoxide (CO), ozone
(O3), nitrogen dioxide (NOx), and lead (Pb).
Clean Water Act--1970
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Initially set standards for pesticide quality, with little consideration for environmental impact
1972 shifted to EPA control, and focused on protecting environment and human health
Seeks to protect human health from the 12 most toxic chemicals (includes 8 chlorinated hydrocarbon
pesticides).
CERCLA--1980
•
Also known as the "Superfund" Act. This regulates mineral processing wastes. Hazardous wastes dumped
somewhere can also be cleaned up through government funding
THE DIRTY DOZEN
The following chemicals are classified as persistent organic pollutants
(POPs)—they persist in the environment and bioaccumulate.
They were identified under the Stockholm Convention of 2001. The US
did not ratify this treaty.
• Aldrin
• Dieldrin
• Chlordane
• DDT
• Endrin
• Mirex
• Heptachlor
• PCBs
• Toxaphene
• Dioxins
• Furans
• Hexacholorobenzene
NATURAL HAZARDS
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Hurricanes
Floods
Tornadoes
Volcanic eruptions
Earthquakes
Landslides
Forest fires
• Some effects preventable (warning systems,
building techniques) others a consequence of
where people choose to live
CULTURAL HAZARDS
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Where live
Criminal activity
Political unrest
Economic development of the country
• Risk factors differ substantially between
developed/developing (access to food, water, healthcare)
LIFESTYLE HAZARDS
• Engaging in risky behavior
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Smoking, drugs, alcohol
Eating too much
Driving too fast
Occupational hazards
sunbathing