The document discusses various environmental hazards, including biological, chemical, and nuclear risks, and emphasizes the importance of risk assessment and management in mitigating these dangers to human health and natural resources. It highlights the significance of infectious diseases, their transmission pathways, and the growing resistance to antibiotics and pesticides, as well as concerns over toxic chemicals and their effects on human health. Additionally, the document addresses the potential risks associated with nuclear radiation, focusing on its effects on living organisms and the necessity for proper regulations and disposal methods.

1. CHY1002 – ENVIRONMENTAL
SCIENCES
Module – 3 – Part-1
Sustaining Natural Resources and
Environmental Quality
1

2. Sustaining Natural Resources and Environmental
Quality
• Environmental hazards: Biological, Chemical,
Nuclear; Risk and evaluation of hazards;
• Water quality management and its conservation;
• Water footprint and virtual water,
• Solid waste management; Climate disruption and
ozone depletion (Kyoto protocol, Carbon
sequestration methods and Montreal Protocol – can
be discussed)
2

3. Environmental
Hazards
Nuclear
Biological
Chemical
3

4. Major Health Hazards
• Biological hazards from more than 1,400 pathogens that can infect
humans.
– A pathogen is an organism that can cause disease in another
organism.
– Examples are bacteria, viruses, parasites, protozoa, and fungi.
• Chemical hazards from harmful chemicals in air, water, soil, food,
and human-made products.
• Physical hazards such as fire, earthquakes, volcanic eruptions,
floods, and storms.
• Cultural hazards such as unsafe working conditions, unsafe
highways, criminal assault, and poverty.
• Lifestyle choices such as smoking, making poor food choices,
drinking too much alcohol, and having unsafe sex.
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5. Risk Assessment & Management
• Risks Are Usually Expressed as Probabilities
• Risk assessment is the process of using statistical
methods to estimate how much harm a particular
hazard can cause to human health or to the
environment – helps to establish priorities for
avoiding or managing risks.
• Risk management involves deciding whether or how
to reduce a particular risk to a certain level and at
what cost.
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7. What Types of Biological Hazards Do We Face?
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• Non-transmissible diseases
– Caused by something other than a living organism.
– Does not spread from one person to another.
– Tend to develop slowly and have multiple causes.
– Examples include cardiovascular diseases, most cancers, asthma, and
diabetes.
• Infectious diseases
– caused when a pathogen such as a bacterium, virus, or parasite
invades the body and multiplies in its cells and tissues.
– Examples are tuberculosis, flu, malaria, and measles.
– Also called a contagious or communicable disease
– An infectious disease that can be transmitted from one person to
another.
– Examples are tuberculosis, flu, and measles.

8. Infectious Diseases are Major Health Threats
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• Infectious diseases can spread through air, water, food
and body fluids such as feces, urine, blood, and
droplets sprayed by sneezing and coughing.
• A large-scale outbreak of an infectious disease in an
area or country is called an epidemic, and a global
epidemic such as tuberculosis or AIDS is called a
pandemic.
• A growing problem is that many disease-carrying
bacteria have developed genetic immunity to widely
used antibiotics.
• Also, many disease transmitting species of insects such
as mosquitoes have become immune to widely used
pesticides such as DDT that once helped to control
their populations.

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Pathways for infectious disease in humans

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Some viral diseases kills large number of humans

11. Growing Global Threat from Tuberculosis
 One of every three persons on the planet is infected with the
TB bacterium and 5–10% of them will eventually become sick
with active TB, according to WHO estimates.
 Many TB-infected people do not appear to be sick, and about
half of them do not know they are infected.
 Left untreated, each person with active TB typically infects 10–
15 other people.
 Without treatment, about half of the people with active TB die
from bacterial destruction of their lung tissue.
 Most strains of the TB bacterium have developed genetic
resistance to the majority of the effective antibiotics.
 Population growth, urbanization, and air travel have greatly
increased person-to-person contacts, and TB is spreading
faster in urban areas where large numbers of poor people
crowd together.
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12. Influenza or Flu virus – HIV/AIDS – Hepatitis B
1. Viruses evolve quickly, are not affected by antibiotics, and can
kill large numbers of people. The biggest killer is the influenza
or flu virus, which is transmitted by the body fluids or airborne
emissions of an infected person.
– The global flu pandemic of 1918, killed 20–50 million people
within a few months and caused economic and social
disruption.
2. The second biggest viral killer is the human immuno deficiency
virus (HIV).
– On a global scale, HIV infects about 2.5 million people each
year, and the resulting complications from AIDS kill about 2
million people annually.
3. The third largest viral killer is the hepatitis B virus (HBV), which
damages the liver and kills about a million people each year.
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13. Some other epidemic viral diseases
• West Nile virus - transmitted to humans by
the bite of a common mosquito that becomes
infected by feeding on birds that carry the
virus.
• Severe acute respiratory syndrome (SARS)
virus- has flu like symptoms, can quickly turn
into life-threatening pneumonia and is easily
spread from person to person.
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14. Malaria
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Global outlook of malaria.
About 40% of the world’s
population lives in areas in
which malaria is prevalent.
• Malaria is caused by a parasite (Plasmodium protozoan
parasites) that is spread by the bites of certain mosquito species
- Anopheles mosquito.
• It infects and destroys red blood cells, causing intense fever,
chills, drenching sweats, anemia, severe abdominal pain,
headaches, vomiting, extreme weakness, and greater
susceptibility to other diseases.
• It kills an average of at least 2,700 people per day.

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1. Most species of the Anopheles mosquito have become
genetically resistant to most insecticides.
2. The Plasmodium parasites have become genetically resistant
to common antimalarial drugs.
Bites often
at night

16. Over the course of human history,
malarial protozoa probably have
killed more people than all the wars
ever fought.
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17. We Can Reduce the Incidence of Infectious
Diseases
• Children in developing countries were immunized with vaccines
to prevent tetanus, measles, diphtheria, typhoid fever, and polio.
• Simple oral rehydration therapy to help prevent death from
dehydration for victims of severe diarrhoea.
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How to greatly reduce the chances of
getting infectious diseases?
1. By practicing good hygiene.
2. Washing hands thoroughly and
frequently.
3. Avoid touching your face, and
4. stay away from people who have
flu or other viral diseases.

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19. • There is growing concern about chemicals that can cause
cancers and birth defects and disrupt the human immune,
nervous, and endocrine systems.
• Toxic chemical - one that can cause temporary or permanent
harm or death to humans and animals.
• In 2004, the U.S. Environmental Protection Agency (EPA) listed
arsenic, lead, mercury, vinyl chloride (used to make PVC
plastics), and polychlorinated biphenyls (PCBs) as the top five
toxic substances in terms of human and environmental health.
• There are three major types of potentially toxic agents.
• Carcinogens
• Mutagens
• Teratogens
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Chemical Hazards that We Face

20. Carcinogens
• Can cause or promote cancer — a disease in which
malignant cells multiply uncontrollably and create tumors
that can damage the body and often lead to premature
death.
• Examples of carcinogens : arsenic, benzene, chloroform,
formaldehyde, gamma radiation, nickel, PCBs, radon,
certain chemicals in tobacco smoke, ultraviolet (UV)
radiation, X-rays, and vinyl chloride.
• 10–40 years may elapse between the initial exposure to a
carcinogen and the appearance of detectable symptoms.
• Due to the time lag, many healthy teenagers and young
adults have trouble believing that their smoking, drinking,
eating, and other habits today could lead to some form of
cancer before they reach age 50.
• According to the American Cancer Society, in 2007, there
were at least 12 million new cancer cases
• 7.6 million cancer deaths—an average of about 21,000
deaths a day. 20

21. Mutagens
• Mutagens - includes chemicals or forms of radiation
that cause mutations, or changes, in the DNA
molecules found in cells, or that increase the frequency
of such changes.
• Some mutations lead to cancers and other disorders.
• For example, nitrous acid (HNO2), formed by the
digestion of nitrite (NO2
–) preservatives in foods, can
cause mutations leading to stomach cancer in people
who consume large amounts of processed foods and
wine with such preservatives.
• Harmful mutations occurring in reproductive cells can
be passed on to offspring and to future generations.
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22. Teratogens
• Teratogens are chemicals that cause harm or
birth defects to a fetus or embryo.
• Ethyl alcohol is a teratogen.
• Drinking during pregnancy can lead to offspring
with low birth weight and a number of physical,
developmental, behavioral, and mental problems.
• Other teratogens are benzene, cadmium,
formaldehyde, lead, mercury, mescaline, PCBs,
phthalates, thalidomide, and vinyl chloride.
• Between 2001 and 2006, birth defects in Chinese
infants soared by nearly 40%. Officials link this to
the country’s growing pollution, especially from
coal-burning power plants and industries.
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Potential pathways on which toxic chemicals such as PCBs
move through the living and nonliving environment.

24. Mercury’s Toxic Effects - Teratogen
• Hg metal is released into the air from rocks, soil, and
volcanoes and by vaporization from the ocean. Such natural
sources account for about one-third of the mercury reaching
the atmosphere each year.
• According to the EPA, the remaining two-thirds come from
human activities—primarily from the smokestacks of coal-
burning power plants and coal-burning industrial facilities.
• China—the world’s largest coal user—mercury emissions
from coal burning power plants and factories are much larger
because of a lack of air quality laws and enforcement.
• Some of the indestructible particles of mercury released in
China end up in the air, water, and soil in the western United
States.
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25. Mercury accumulation
• Hg is converted to more toxic inorganic and organic mercury
compounds that can be deposited in aquatic environments.
• In acidic aquatic systems, bacteria can convert inorganic
mercury compounds to highly toxic methylmercury, which can
be biologically magnified in food chains and webs.
• High levels of methylmercury (CH3Hg+) are often found in the
tissues of large fishes such as albacore (white) tuna, sharks,
swordfish, king mackerel, tilefish, walleye, and marlin.
• Humans are exposed to mercury in three ways.
– By inhaling vaporized elemental Hg or particles of inorganic mercury
salts such as HgS and HgCl2.
– By eating fish contaminated with highly toxic CH3Hg+.
– High fructose corn syrup is widely used as a sweetener in beverages
and food products.
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26. Health hazards of mercury
• Brain damage in fetuses and young children -
Reduced IQs and other neurological problems
• Methylmercury may also harm the heart, kidneys,
and immune system of adults.
• In 2004, the U.S. Food and Drug Administration
(FDA) and the EPA advised nursing mothers,
pregnant women, and women who may become
pregnant not to eat shark, swordfish, king
mackerel, or tilefish and albacore tuna or limit
their consumption.
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27. Remedy?
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28. Chemicals Affecting Our Immune, Nervous Systems
• The immune system consists of specialized cells and tissues
that protect the body against disease and harmful substances
by forming antibodies that render invading agents harmless.
• Some chemicals such as arsenic, methylmercury, and dioxins
can weaken the human immune system and leave the body
vulnerable to attacks by allergens and infectious bacteria,
viruses, and protozoa.
• Neurotoxins, can harm the human nervous system (brain,
spinal cord, and peripheral nerves).
• Effects can include behavioral changes, learning disabilities,
retardation, attention deficit disorder, paralysis, and death
• Examples of neurotoxins are PCBs, methylmercury, arsenic,
lead, and certain pesticides.
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29. Chemicals disrupting endocrine systems
• The endocrine system is a complex network of glands that
release tiny amounts of hormones into the bloodstreams of
humans and other vertebrate animals.
• Low levels of these chemical messengers turn on and turn off
bodily systems that control sexual reproduction, growth,
development, learning ability, and behavior.
• Each hormone has a unique molecular shape that allows it to
attach to certain cells, using a part of the cell called a receptor,
and to transmit its chemical message.
• In this “lock-and-key” relationship, the receptor is the lock
and the hormone is the key.
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30. • Molecules of certain pesticides and other synthetic chemicals such as
bisphenol A (BPA) have shapes similar to those of natural hormones. This
allows them to attach to molecules of natural hormones and disrupt the
endocrine system in people and some other animals. These molecules are
called hormonally active agents (HAAs).
• Examples of HAAs: aluminum, atrazine and several other herbicides, DDT,
mercury, PCBs, phthalates, and BPA.
• BPA are chemically similar to estrogens and can disrupt the endocrine
system by attaching to estrogen receptor molecules.
• Hormone blockers, disrupt the endocrine system by preventing natural
hormones such as androgens from attaching to their receptors.
• Estrogen mimics and hormone blockers are sometimes called gender
benders because of their possible effects on sexual development and
reproduction.
• Some HAAs—pollutants that can act as thyroid disrupters and cause
growth, weight, brain, and behavioral disorders.
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Chemicals disrupting endocrine systems

31. BPA
• In 2008, the U.S. Food and Drug Agency (FDA) concluded that
BPA is toxic . Canada classified BPA as a toxic substance and
announced a ban on its use in baby bottles
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Does it contain
only the delicious
milk?

32. Phthalates
• There is also growing concern over possible harmful effects
from exposure to low levels of certain phthalates. These
chemicals are used to soften polyvinyl chloride (PVC) plastic
found in a variety of products and used as solvents in many
consumer products.
• Phthalates are found in many perfumes, cosmetics, baby
powders, body lotions, hair sprays, deodorants, nail polishes,
and shampoos for adults and babies.
• They are also found in PVC products such as soft vinyl toys,
teething rings, and blood storage bags, IV bags, and medical
tubes used in hospitals.
• Phthalates can cause birth defects and liver cancer, kidney
and liver damage, premature breast development, immune
suppression, and abnormal sexual development.
• The European Union and at least 14 other countries have
banned phthalates.
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33. How Can We Evaluate Chemical Hazards?
• Many Factors Determine the Harmful Health Effects of a Chemical
• Toxicity is a measure of the harmfulness of a substance—its
ability to cause injury, illness, or death to a living organism.
• At what level of exposure to a particular toxic chemical will the
chemical cause harm?
• Solubility. Water/fat soluble toxins.
• Persistence, or resistance to breakdown.
• Biological magnification.
• Protecting Children from Toxic Chemicals.
• Scientists Use Live Laboratory animals and Non-animal Tests to Estimate
Toxicity.
• Are Trace Levels of Toxic Chemicals Harmful?
• Why Do We Know So Little about the Harmful Effects of Chemicals?
• How Far Should We Go in Using Pollution Prevention and the
Precautionary Principle?
33Pg- 358-360

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35. The Greatest Health Risks Come from Poverty and
Lifestyle Choices
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36. 36
Cigarette smoking is the world’s
most preventable major cause of
suffering and premature death
among adults.
Annual deaths in the United States
Bad life styles / habits

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Nuclear Hazards

38. 38

39. Radioactivity
• Radioactive substance are present in Nature
• Undergo natural radioactive decay in which
unstable isotopes spontaneously give out fast
moving particles, high energy radiation or
both, at a fixed rate until a new isotope is
formed
• Energy: gamma rays or Ionization Particles
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40. Radioactive decay
• Radioactive substances undergo radioactive
decay – unstable atoms to stable atoms.
• Radioactive decay release energy
1. Gamma rays – High energy electromagnetic
radiation
2. Alpha particles – Fast moving +vely charged
particles
3. Beta particles – Fast moving –vely charged
particles.
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44. 44
Penetration power of ionization radiations emitted
by radioisotopes
Beta – wood or few millimeters of aluminum sheet

45. 45

46. 46
Effects of Radioactivity
• Radiation affects all living organisms
• Causes harmful changes in the body cells and also in
the genetic level
i) Genetic damage: Induces mutation in DNA-affects
genes and chromosomes.
-damage is often seen in offspring and may be
transmitted up to several generations
ii) Somatic damage: Includes burns, miscarriages, eye
cataracts and cancer in bone, thyroid, breast, lungs
and skin

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Genetic effects are damages to genes and chromosomes that
affect future generations.
Somatic effects are cell damages that pass on to succeeding cell
generations.
Effects of Radioactivity

48. 48
• Damage depends on the penetration level of the radiation
• α-particles have less penetration power than β- particle
• Radio isotopes enter into the environment during mining of
Uranium
• Radio isotopes enter in to humans by water (contamination of
underground bodies) & food (Radioactivity in the earth’s crust
enters the crops grown there)
• Radioactive Iodine (I131)- thyroid gland - Cancer
• Radioactive Strontium (Sr90)—bones – Leukemia or cancer of
bone marrow
Effects of Radioactivity

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Acute exposure is sudden exposure to higher levels of radiation
over a short period of time.
Radiation leakage accidents:
- Radiation treatment labs
- Nuclear plants
Chronic exposure is continuous exposure to low levels of
radiation over a long period of time
- Handling nuclear waste
- Soil contaminants
- Water contaminants
No radiation exposure is completely risk free
Effects of Radioactivity

50. Nuclear pollution - Control
• Proper assessment of long term and short
term effects before setting a nuclear power
plant.
• Proper protection and precautions.
• Proper regulations.
• Proper disposals of nuclear wastes.
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