A P E S C H A P T E R 1 7
TOXICOLOGY
“All substances are poisons: there is none which is not a poison. The right dose differentiates a poison and a remedy." Paracelsus (1493-1541)
• 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)• 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
• Clean Air Act--1970• 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• 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• 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• 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
• Aldrin• Dieldrin• Chlordane• DDT• Endrin• Mirex
• Heptachlor• PCBs• Toxaphene• Dioxins• Furans• Hexacholorobenzene
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.
NATURAL HAZARDS
• 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
• 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• Smoking, drugs, alcohol• Eating too much• Driving too fast• Occupational hazards• sunbathing