Chapter 17 and 21
“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
 Risk management
 Biological, chemical, natural, cultural and lifestyle
hazards
Biological Hazards
 Infectious disease (flu, malaria, TB)
 Transmissible disease (measles, HIV)
 Nontransmissible disease (cancer, asthma, diabetes,
malnutrition)
 Major concerns include flu, AIDS (HIV), Hepatitis B,
malaria and emergent diseases (west nile, Ebola)
 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
 Carcinogen: promotes cancer
 Arsenic, benzene, formaldehyde, gamma and UV radiation, PCBs,
radon, tobacco smoke, vinyl chloride
 Mutagen: increases frequency of mutations
 Teratogen: cause harm or birth defects to fetus/embryo
 Alcohol, benzene, formaldehyde, lead, mercury, PCBs, phalates,
thalidomide, vinyl chloride
Chemical Hazards
 Neurotoxins (disrupt nervous system—brain, spinal
cord)
 PCBs, arsenic, lead, pesticides, methylmercury
 Endocrine disruptors (alter hormones and
development)
 BPA, Aluminum, atrazine, DDT, PCBs, mercury,
pthalates
 Immune system disruptors (limit immune response)
 Arsenic, methylmecury, dioxins
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
The Dirty Dozen
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*Go to
BPA
http://toxtown.nlm.nih.gov/text_version/chemical
Dioxins
s.php and click on “Chemicals” at the top of the
page.
Pthalates
PCBs
*Find your chemical on the list and answer the
Arsenic
following questions…
Benzene
1. Describe what the chemical is. What
Formaldehyde
products/processes is it found in?
Mercury
2. Where is the chemical located in the
Asbestos
environment? How does it get there? How
Lead
are humans exposed to it?
Vinyl Chloride (PVC)
3. What are the health concerns?
Ethylene Glycol
Waste Management
 Solid waste: any unwanted or discarded material we
produce that is not a liquid or a gas
 Industrial solid waste- produced by mines, farms and
industry (40%)
 Municipal solid waste (MSW)- produced by homes
and workplaces; ends up in landfills/incinerators (60%)
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Average 4.5 pounds per person per day!
 Hazardous toxic waste- threatens human health
because it is poisonous, chemically reactive, corrosive or
flammable
Waste
 Managing waste refers to
controlling the
environmental harm of
waste, not decreasing its
production
 Reducing waste is
concerned with
producing less waste and
pollution (prevention)
 Recycling is reusing or
repurposing materials
instead of throwing them
away
What do we throw away?
 Paper (31%)
 Food (13%)
 Yard waste (13%)
 Wood (7%)
 Rubber, Leather
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and Clothing (8%)
Plastic (12%)
Metal (8%)
Glass (5%)
Other (3%)
Recycling
 Importance…
 Decreases use of energy making
products
 Decreases waste and pollution
(amount into landfills)
 Increases jobs
 Saves $$$
 Primary (closed-loop) recycling: materials recycled into new
products of the same type (aluminum to aluminum)
 Secondary (open-loop) recycling: waste materials converted
into different products (plastic to clothing)
Burning and Burying Waste
 Waste-to-Energy Incinerators (13%)
 Garbage and waste is burned, water is boiled and energy is
created
 Produces high number of pollutants
 Sanitary Landfills (54%)
 Waste buried underground in layers, alternating with clay,
plastic or foam; sides of landfill are lined to prevent leaching
of chemicals; pipes to collect leaching liquid (prevent soil and
water contamination)
 Methane (byproduct of decomposition) is collected and
burned for fuel
 Concerns about chemicals leaking to groundwater (leachate)
Hazardous Waste
 Priority in reducing waste
 Most comes from industrial processes (textiles, computer
manufacturing, dry cleaners, service stations)
 Difficult to dispose of…responsibility is on company or
homeowner
 Can convert to non-hazardous substances
 Physical, chemical or biological methods
 Must be treated before disposal
 Stored forever
 Deep well disposal
 Surface impoundments
 Steel Drums
Legislation
 Resource Conservation and Recovery Act
 Manages hazardous waste, “cradle-to-grave” tracking
 CERCLA (Superfund Act)
 Identifies contaminated sites
 EPA manages National Priorities List
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Currently about 1200 sites
Funding for clean-up is lacking
 Brownfield: abandoned industrial and commercial sites,
contaminated with hazardous waste