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EESA10H3 Study Guide - Midterm Guide: Gamma Ray, Beta Particle, Tetraethyllead

Environmental Science
Course Code
Silvija Stefanovic
Study Guide

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EESA10 Midterm Exam Notes
Week 1:
Chapter 1:
Environment: a complex system of living things and natural processes, the human species is one
player in this web
Hazards: chemical, biological, physical
Chemical - industrial, pollutants, pesticides, lead in paint, cigarette smoke
Biological - “biohazards” agents of infectious disease (mold, GMOs)
Physical - contact with energy (radiation, noise, airborne dust particles, mechanical
objects, extremes of heat and cold)
Environmental health: More than industrial pollution, not based on genetic traits. Does not
include an analysis of the effect of genetics on the likelihood of illness / injury from exposure to
chemicals and hazards as a cause of disease
Social / Behavioural Hazards: (drug use) not a part of environmental health. Environmental
health does not consider the link between hazards and social behavioural elements
Greater focus on anthropogenic hazards than naturally occurring hazards (floods, tsunamis,
windstorms). Natural disasters can however create environmental health hazards - an example
would be the ‘soup’ of industrial sewage wastes from Hurricane Katrina affecting health.
“In an ecosystem nothing ever goes away” - Barry Commoner
21st century- our stuff and its byproducts remain in the environment. Western style development
is not sustainable. There is also a large disparity between developed and less developed
TRANSCRIPT: “Everyday Carcinogens: Stopping Cancer Before It Starts” -
Dr Sandra Steingraber
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There are 12 evidences linking cancer and the environment in Steingraber’s book “Living
Downstream” - the article covers 4
Thesis: no one study gives absolute proof of a link between cancer and the environment. All the
studies fit together like a puzzle, the make sense together.
1. Cancer Registries: measure of cancer incidences in a population
Canada and the U.S are very similar
Non tobacco related cancers are rising in incidence among all age groups - this is since
the early 70s dating back to WWI
This is not caused by lifestyle / hereditary factors / it’s partly because of lack of early
screening but mostly not
Childhood cancers have doubled since 1959. 10% rise in 10 years
Rise in testicular cancer in men 19-45 / tripled since WWI
Non Hodgkins Lymphoma has doubled over 4 decades. Multiple Myeloma also doubled
in 40 years
Brain cancers growing in children, 54% up in 2 decades
All these rises have not been caused by lifestyle, diet, exercise, more early screening, or
heredity, which would indicate maybe the environment is at play.
2. Computer Mapping - cancer registry data displayed over space instead of time
Cancer is not random
Ex- Great Lake Basin / Eastern Seaboard Great Lakes Region - breast / colon/ bladder
cancer high in these regions that are highly industrialized
There is a correlation between environment and cancer
Highly industrialized = greater cancer - this may not be causation though
Non Hodgkins Lymphoma is high in the Great Plains, Kansas, Nebraska, Iowa, Illinois,
Wisconsin where there is high pesticide use
3. Our Own Bodies - humans have several chemicals in their bodies from exposure
Pesticides, industrial solvents, PCBs, dioxins…
Common in Hamilton
Chemicals go to breast milk, fat, blood, semen, hair, umbilical cords, fluid surrounding
human eggs.
Chemicals linked to cancer in bodies
New Development: need to assess endocrine disruptors that interfere with hormones in
addition to chemicals causing mutations
Hormones are messengers directing genes
Chemicals mimicking hormones don’t damage genes they disrupt the message. They are
trespassers that send a message not meant to be sent
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These chemicals work with elements already in the body. They may cause faster
development of cancer
Timing of Exposure: an old thinking was “the dose makes the poison” meaning one could
regulate carcinogens to a low level that is not harmful
New Science: each person has windows of vulnerability when they are especially
sensitive to chemicals. The prenatal period - exposure in the womb intensifies exposure
later on in life. Adolescence - girls breasts must be shielded when getting an Xray as this
intensifies risk of cancer
4. Animals - parallel between cancer in animals and in humans
Animals in pristine regions don’t develop certain cancers
Ex: Beluga whales in the St Lawrence river have high cancer rates because the river is
less clean
Non Hodgkins is high where there is high use of pesticides
Farmers have high raters of it, Vietnam veterans exposed to Agent Orange (a weed killer)
have it
Dogs whose owners use lawn chemicals are more prone to get cancer
Hodgkins- chromosome breaks, flips and reattaches itself - pesticide applicators have this
Dioxin- break milk heavily contaminated by it,foods from animal flesh second most
Dioxin is a byproduct of burning plastic - big issue in Hamilton
Dioxin (in the air) goes into body through consumption and accumulates over time
Animals feed on plants with particles and dioxin enters the food chain
The contaminants in a woman’s body find their way into the next generation through
breast milk
Animals are better to study because they don’t have lifestyle factors causing cancer
Burden of proof in science is 95% - in 1964 a surgeon announced smoking as cancer
causing without much proof. Steingraber argues there should be an effort to fight for
uncontaminated breast milk though scientific proof isn't at the 95% mark
Week 2:
Lecture 2
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