Rutgers The State COVID 19 Lockdown and Domestic Violence in Bangladesh Paper Hi I have assignment to do ,in the same way that described below. Chapter 10N | Course Hero
Rutgers The State COVID 19 Lockdown and Domestic Violence in Bangladesh Paper Hi I have assignment to do ,in the same way that described below. Chapter 10News Story students will find a news story (local, regional, or international) that relates to the topics (Chapters) covered that week. A ONE paragraph summary of the news story news story and a link to the news story.the chapter is attached. Essential Environment: The Science Behind the Stories
Sixth Edition
Chapter 10
Environmental Health
and Toxicology
Lecture Presentations prepared by
James Dauray
College of Lake County
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This lecture will help you understand:
Explain the goals of environmental health and identify major
environmental health hazards.
Describe the types of toxic substances in the environment,
factors that affect their toxicity, and the defenses that organisms
have against them.
Explain the movement of toxic substances and how they affect
organisms and ecosystems.
Discuss the approaches used to study the effects of toxic
chemicals on organisms.
Summarize risk assessment and risk management.
Compare approaches to risk and regulatory policy.
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Poison in the Bottle: Is Bisphenol A Safe? (1 of 3)
The chemical bisphenol A (BPA) is in
hundreds of everyday products, yet it
has been linked to breast cancer,
prostate cancer, and heart disease.
BPA is an additive used to make
the coatings of metal cans, dental
sealants, and the polycarbonate
plastic found in water bottles, toys,
and electronics.
Many plastic products also contain a
class of hormone-disrupting
chemicals called phthalates.
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Poison in the Bottle: Is Bisphenol A Safe? (2 of 3)
Many studies have examined the relationship between
BPA, phthalates, and a wide range of adverse health
effects.
Figure 10.1 Studies have linked elevated blood/urine BPA concentrations to numerous health
impacts in humans.
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Poison in the Bottle: Is Bisphenol A Safe? (3 of 3)
Research finding correlations between BPA and phthalate
exposure and a variety of health problems has caused
some governments to issue regulations.
Canada has banned BPA use outright.
The United States restricts its use in childrens
products.
Many food companies are phasing these out of food
packaging and labeling packaging as BPA- or phthalatefree.
This is one example of how a society assesses health risks
and decides how to manage them.
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Environmental Health
Environmental health is a field that assesses
environmental factors that can influence our health and
quality of life.
These include both natural and anthropogenic factors.
Environmental hazards are categorized into four types,
each of which carries some risk that is avoidable and some
that is not.
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We face four types of environmental hazards (1 of 4)
Physical hazards arise
from natural environmental
processes, such as UV
radiation from sunlight and
natural disasters.
These risks can be
reduced with protective
measures, such as
sunblock and disaster
detection and warning
systems.
Figure 10.2 Environmental health hazards
come in four types.
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We face four types of environmental hazards (2 of 4)
Chemical hazards include
synthetic chemicals such as
pharmaceuticals, disinfectants,
and pesticides, and natural
toxins like venom.
[Figure 10.2 Continued]
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We face four types of environmental hazards (3 of 4)
Biological hazards result
from interactions with other
organisms, such as viruses,
bacteria, insects, or parasites.
Infectious disease are
illnesses that can be
spread from person-toperson.
Vectors are organisms
that transfer diseases to
their host.
[Figure 10.2 Continued]
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We face four types of environmental hazards (4 of 4)
Cultural hazards occur as the
result of our place of
residence, socioeconomic
status, occupation, or
behavioral choices.
Choosing to smoke,
accompanying people who
smoke, poor diet, drug use,
and workplace hazards are
all examples.
[Figure 10.2 Continued]
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Disease is a major focus of environmental health (1 of 2)
Infectious and noninfectious diseases cause the majority of human
deaths worldwide.
Noninfectious diseases develop without the action of a foreign
organism.
Figure 10.3 Infectious diseases are the second-leading cause of death worldwide.
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Disease is a major focus of environmental health (2 of 2)
Infectious diseases spread when a pathogenic organism enters a host
through the skin, via the respiratory system, or by the consumption of food
or water.
Immunization, public sanitation, access to clean water, food security,
and public education all help to reduce infectious disease.
Figure 10.3 Infectious diseases are the second-leading cause of death worldwide.
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Toxicology is the study of chemical hazards
Toxicology is the science of examining the effects of
poisonous substances on humans and other organisms.
Toxicity is the degree of harm caused by a chemical
substance called a toxicant.
Any chemical has the potential to be a toxicant, depending
on the dose and level of exposure.
Environmental toxicology is the study of anthropogenic
chemicals released into the environment that have human
health effects.
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Many environmental health hazards exist indoors (1 of 2)
Cigarette smoke and radon are leading indoor health
hazards and the top two causes of lung cancer.
Radon is a radioactive gas that seeps up from certain
types of bedrock. It is colorless and undetectable
without specialized kits.
Asbestos is a substance that was used in the past as
insulation in walls and other products and is highly toxic
when inhaled.
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Many environmental health hazards exist indoors (2 of 2)
Lead is a heavy metal that, when ingested, damages the
brain, liver, kidney, and stomach.
This condition is called lead poisoning and has greatly
declined since the phaseout of lead-based paint and
leaded gasoline in the 1970s.
Polybrominated diphenyl ethers (PBDEs) are
compounds used as fire retardants in a variety of products,
including electronics, plastics, and furniture.
Similar to BPA, PBDEs act as hormone disruptors,
interfering with thyroid hormones.
The European Union banned PBDEs in 2003, but they
have not yet been addressed in the United States.
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Risks must be balanced against rewards
Chemicals have played a crucial role in increasing our
standard of living, but their use carries a potential human
health risk.
Toxicologists try to weigh the benefits and risks of each
chemical to determine whether it should be widely used.
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Toxic Substances and Their Effects on
Organisms
The environment contains many natural toxic substances,
such as petroleum, radon gas, and toxins.
Toxins are toxic chemicals manufactured in the tissues
of living organisms, often used as defense against
others.
We are also exposed to many synthetic (artificial, manmade) chemical substances.
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Silent Spring began the public debate over synthetic
chemicals (1 of 2)
Prior to the 1960s, pesticides were indiscriminately
sprayed over residential neighborhoods and public areas,
on an assumption that the chemicals would not harm
people.
Rachel Carson published Silent Spring in 1962, using
scientific studies and case histories to demonstrate that
pesticides like DDT were harmful to people.
Although the chemical industry challenged the book,
public outcry led to the banning of DDT in the United
States.
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Silent Spring began the public debate over synthetic
chemicals (2 of 2)
Synthetic chemicals,
such as DDT, take many
routes traveling through
the environment.
Figure 10.4 Synthetic chemicals take many
routes in traveling through the environment.
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Not all toxic substances are synthetic
Many toxic substances exist naturally in the environment
and in the foods we eat.
It is a mistake to assume that all artificial substances
are unhealthy and all natural substances are healthy.
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Toxic substances come in different types (1 of 3)
Carcinogens are substances or types of radiation that
cause cancer.
Cancer occurs when malignant cells grow
uncontrollably, creating tumors and often leading to
death.
Mutagens are substances that cause genetic mutations in
the DNA of organisms.
Most mutations have little or no effect, but some can
lead to severe problems like cancer.
Teratogens specifically cause birth defects.
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Toxic substances come in different types (2 of 3)
Neurotoxins such as heavy metals damage the nervous
system.
Allergens overactivate the immune system, causing an
immune response when one is not necessary.
One hypothesis for the recent increase in asthma is the
prevalence of allergenic synthetic chemicals.
Pathway inhibitors block one or more steps in important
biochemical pathways.
Cyanide, for example, interrupts the chemical
pathways that produce energy in mitochondria.
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Toxic substances come in different types (3 of 3)
Endocrine disruptors interfere with the functions of body
hormones, either by blocking them, accelerating their
breakdown, or mimicking their effects.
Both BPA and phthalates are endocrine disruptors, with
BPA mimicking the female hormone estrogen.
Figure 10.5 Many endocrine-disrupting substances mimic the chemical structure of hormone
molecules.
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Organisms have natural defenses against toxic
substances
Organisms have evolved ways to tolerate harmful
substances naturally present in the environment to gain an
evolutionary advantage.
Skin, scales, and feathers resist uptake from the
surrounding environment.
Metabolic pathways can break down toxic substances
or make them water soluble so they can be excreted
through the kidneys.
Substances that cannot be metabolized are sequestered
by the body in fatty tissues to protect vital organs.
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Individuals vary in their responses to hazards
An individuals sensitivity to a given toxin will vary
depending on genetics, overall health, gender, and age.
In general, those in poorer health, individuals of smaller
size, and younger organisms with developing organ
systems tend to be more sensitive.
The EPA extrapolates chemical exposure standards for
adults down to infants and children.
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The type of exposure can affect the response
The risk of a hazard also varies according to whether a
person experiences high exposure for short periods of time
(acute exposure) or low exposure for long periods of time
(chronic exposure).
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Toxic Substances and Their Effects on
Ecosystems
When toxicants concentrate
in environments and harm
the health of many
individuals, populations of
the affected species can
become smaller.
One example of this is
the contamination of the
Earths polar regions
that occurs as a result of
natural patterns of
global atmospheric
circulation.
Figure 10.6 Air and water currents direct
pollutants to the poles.
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Toxic substances may concentrate in water
Toxic substances are not evenly distributed in the
environment and move about in specific ways.
Water running off from land often transports toxicants
from large areas and concentrates them in surface
water.
Wastewater treatment plants add toxins,
pharmaceuticals, and detoxification products to
waterways.
Chemicals in soil can leach into groundwater and
contaminate drinking water supplies.
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Some toxicants persist in the environment
The rate at which a substance degrades in the
environment depends on its chemistry and on external
factors like temperature, moisture, and sun exposure.
We have designed many chemicals, such as those in
plastics, to be persistent and resist degradation.
Over time, most toxicants degrade into simpler
compounds called breakdown products, which may
be less or equally harmful as the original substance.
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Toxic substances may accumulate and move up the
food chain (1 of 2)
Substances that are fat or oil soluble are absorbed and
stored in body tissues.
Given enough time and exposure, bioaccumulation
will occur, and the concentration of the substance in
the animals tissues will exceed that of the
environment.
Toxic substances that bioaccumulate will be transferred to
other organisms as predators consume prey.
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Toxic substances may accumulate and move up the
food chain (2 of 2)
As predators ingest more
and more prey over time,
biomagnification occurs,
resulting in greater and
greater concentrations of
the toxin.
Biomagnification of DDT
caused many North
American birds of prey
to decline from the
1950s through the
1970s due to a thinning
of the shells of the eggs
they would lay.
Figure 10.7 In a classic case of biomagnification,
DDT becomes highly concentrated in fish-eating
birds such as ospreys.
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Studying Effects of Hazards
Determining the health effects of a hazard is complex.
Wildlife toxicologists take measurements, document
patterns, and generate hypotheses in the field before
conducting controlled experiments in the lab.
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Wildlife studies integrate work in the field and lab (1 of 2)
Biologist Louis Guillette compared blood samples
of alligators in lakes that received agricultural runoff
with those in cleaner lakes and found hormonal
imbalances in those exposed to pesticides.
Males had low levels of testosterone, while females
had elevated levels of estrogen.
He followed this up with lab experiments demonstrating
that atrazine, an herbicide, was inducing production of an
enzyme that converts testosterone to estrogen.
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Wildlife studies integrate work in the field and lab (2 of 2)
Researcher Tyrone Hayes
found similar reproductive
problems in frogs and
attributed them to atrazine
as well.
Male frogs raised in
contaminated water
became feminized and
hermaphroditic.
Field surveys confirmed
that leopard frogs in
areas of heavy atrazine
usage had hormonal
problems.
Figure 10.8 Wildlife studies examine the effects
of toxic substances in the environment.
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Human studies rely on case histories, epidemiology,
and animal testing (1 of 2)
The process of observation and analysis of individual
patients is known as a case history approach.
Case histories help us understand disease, but tell little
about probability, risk, and population-level effects.
Epidemiological studies are large-scale comparisons
among groups of people.
Involves tracking groups of people for a long period of
time and looking for observable differences in rates of
deaths, cancer, and other health problems.
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Human studies rely on case histories, epidemiology,
and animal testing (2 of 2)
The epidemiological process is akin to a natural
experiment in which the experimenter studies groups of
research participants made available by some event that
has occurred.
These experiments do not confirm that the health
hazard actually causes the effect.
Establishing causation requires manipulative experiments
that are not ethically possible with human subjects.
Animals, such as mice and rats, are used in place of
humans, because their bodies function similarly to
ours.
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Dose-response analysis is a mainstay of toxicology (1 of 4)
A dose-response analysis involves quantifying the
toxicity of a substance by measuring its effects on animals
at different doses.
The dose is the amount of substance the animal
receives.
The response is the type of magnitude of toxic effects
the animal exhibits as a result of the dose.
Data from this analysis is plotted on a graph, with dose on
the x-axis and response on the y-axis.
This generates a dose-response curve.
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Dose-response analysis is a mainstay of toxicology (2 of 4)
The amount of substance
needed to kill half the
population of study
animals, the LD50, is
determined from the
curve.
A high LD50 indicates
low toxicity.
A low LD50 indicates
high toxicity.
Figure 10.9 Dose-response curves show that
organisms responses to toxicants may sometimes
be complex.
For a nonlethal toxicant,
an effective dose50% or
ED50may be measured
instead.
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Dose-response analysis is a mainstay of toxicology (3 of 4)
Responses to some toxicants only occur above a certain
dose, or threshold.
This is called a threshold dose and is observed when
the bodys organs can metabolize or excrete a toxicant
at low doses but get overwhelmed at high doses.
[Figure 10.9 Continued]
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Dose-response analysis is a mainstay of toxicology (4 of 4)
Responses may decrease as a dose increases, producing
U-shaped or J-shaped curves.
This type of curve is often the result of endocrinehormone disruptors, as the body is geared to respond to
minute doses.
[Figure 10.9 Continued]
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Chemical mixes may be more than the sum of their
parts
Mixed toxicants may sum, cancel out, or multiply each
others effects.
The DDT breakdown product DDE can either help
cause sex reversal or inhibit it in alligators, depending
on the presence of other chemicals.
Synergistic effects occur when the interactive impacts of
chemicals are greater than the sum of their individual
effects.
Toxicology attempts to use complex experimental
designs to incorporate these effects, but they are
largely unknown.
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Endocrine disruption poses challenges for toxicity
Because so many synthetic chemicals exist at very low
concentrations over mass areas, their dangers arent fully
known.
Scientists have found that elevated levels of BPA exposure
are linked to:
Higher breast cancer rates in women.
Elevated rates of erectile dysfunction and reduced
sperm counts …
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