The document provides an overview of ecotoxicology. It discusses topics such as types of contaminants like pollutants, poisons and toxicants. It also covers sources of contaminants from both point sources and non-point sources. Additionally, it examines the nature of toxicants, common types of environmental hazards, and factors that influence toxicity. Finally, it briefly outlines how toxicity can impact organisms and different approaches to mapping environmental hazards and toxicity testing.
Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollutants, the components of pollution, can be either foreign substances or naturally occurring contaminants. Pollution is classed as point source or nonpoint source. There are many types of ocean pollutants that endanger ocean life. Some of them are more obvious than others, but all contribute to an unhealthy ocean and many times, the death of its creatures
BOS 4201, Toxicology 1 Course Learning Outcomes for U.docxaryan532920
BOS 4201, Toxicology 1
Course Learning Outcomes for Unit III
Upon completion of this unit, students should be able to:
2. Explain how toxins are processed in biological systems.
2.1 Calculate the mean, median, mode, and dispersion in different types of toxins.
3. Assess the environmental risk of chemical substances based on toxicity.
3.1 Differentiate between pollution and contamination.
3.2 Describe the processes by which chemicals move through the environment.
Course/Unit
Learning Outcomes
Learning Activity
2.1 Unit Lesson, Unit Readings
3.1
3.2
Unit Lesson, Unit Readings
Reading Assignment
Chapter 5:
Environmental Pollutants and Their Fate
Chapter 6:
Dose and Response
Unit Lesson
This unit discusses the risks to the
environment from chemical contamination.
Historical incidents are explored in addition
to the factors that affect the fate of
chemicals in the environment. In the past, it
was thought that dilution was the solution to
pollution. Chemicals were released into the
environment, and it was thought that these
chemicals would just blow away until
researchers found persistent chemicals in
locations where they were not being used.
As this became known, new technologies
were invented to capture or reduce the
amount of chemicals.
Chemicals are found almost everywhere in
our environment. They enter our food chain
and can accumulate in animals. As
humans, we are at the top of the food
chain; breastfeeding infants is at the highest level. It has been theorized that infants are the most exposed
group to environmental contaminants.
UNIT III STUDY GUIDE
Environmental Risks
The pollution response unit at the Naval Air Station in Pensacola,
Florida., deploys oil containment booms at Sherman Cove to protect
environmentally sensitive grass beds from the Deepwater Horizon oil
spill on May 4, 2010.
(Nichols, 2010)
BOS 4201, Toxicology 2
UNIT x STUDY GUIDE
Title
Environmental Pollutants and Their Fate
Pollution is defined as any change in the characteristic of the air, water, or soil that will adversely affect the
health of an organism. A pollutant is any substance released into the environment that may cause adverse
effects. The ecosystem is complex with abiotic and biotic factors being interrelated. Pollutants are often
introduced into the ecosystem and carried into the atmosphere. Precipitation—in the form of rain, sleet, or
snow—can pull the pollutants from the atmosphere and deposit them onto land and into bodies of water,
causing contamination in the soil and water.
Below are some examples of common pollutants found in the environment:
gases (nitrogen oxides and sulphur dioxide),
metals (lead and mercury),
organics (benzene and toluene),
noise,
photochemical oxidants (ozone), and
radioactive wastes.
The fate of chemicals in the environment is affected by the process in which chemicals are moved and
transforme ...
An environmental hazard is a substance, a state or an event which has the potential to threaten the surrounding natural environment / or adversely affect people's health, and natural disasters such as storms and earthquakes.
Any single or combination of toxic chemical, biological, or physical agents in the environment, resulting from human activities or natural processes, that may impact the health of exposed subjects, including pollutants such as heavy metals, pesticides, biological contaminants, toxic waste, industrial and home chemicals.
Human-made hazards while not immediately health-threatening may turn out detrimental to man's well-being eventually, because deterioration in the environment can produce secondary, unwanted negative effects on the human ecosphere. The effects of water pollution may not be immediately visible because of a sewage system that helps drain off toxic substances. If those substances turn out to be persistent (e.g. persistent organic pollutant), however, they will literally be fed back to their producers via the food chain: plankton -> edible fish -> humans. In that respect, a considerable number of environmental hazards listed below are man-made (anthropogenic) hazards.
Hazards can be categorized in four types:
Chemical
Physical (mechanical, etc.)
Biological
Chemical hazards are defined in the Globally Harmonized System and in the European Union chemical regulations. They are caused by chemical substances causing significant damage to the environment. The label is particularly applicable towards substances with aquatic toxicity. An example is zinc oxide, a common paint pigment, which is extremely toxic to aquatic life.
In this Lecture will cover these Contents
1) Definition of environment
2) Components of environment
3) Environmental health
4) Environmental hazards
5) Human and Environment
6) Environment and technology
7) Improving Human Health & Environment
8) Major Environmental Problems in Somalia.
The USEPA defines biodegradation as a process by which microbial organisms transform or alter (through metabolic or enzymatic action) the structure of chemicals introduced into the environment.
According to the definition by the International Union of Pure and Applied Chemistry, the term biodegradation is “Breakdown of a substance catalyzed by enzymes in vitro or in vivo.
The term is often used in relation to ecology, waste management, biomedicine, and the natural environment (bioremediation) and is now commonly associated with environmentally friendly products that are capable of decomposing back into natural elements.
Biodegradable matter is generally organic material such as plant and animal matter and other substances originating from living organisms, or artificial materials that are similar enough to plant and animal matter to be put to use by microorganisms.
Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollutants, the components of pollution, can be either foreign substances or naturally occurring contaminants. Pollution is classed as point source or nonpoint source. There are many types of ocean pollutants that endanger ocean life. Some of them are more obvious than others, but all contribute to an unhealthy ocean and many times, the death of its creatures
BOS 4201, Toxicology 1 Course Learning Outcomes for U.docxaryan532920
BOS 4201, Toxicology 1
Course Learning Outcomes for Unit III
Upon completion of this unit, students should be able to:
2. Explain how toxins are processed in biological systems.
2.1 Calculate the mean, median, mode, and dispersion in different types of toxins.
3. Assess the environmental risk of chemical substances based on toxicity.
3.1 Differentiate between pollution and contamination.
3.2 Describe the processes by which chemicals move through the environment.
Course/Unit
Learning Outcomes
Learning Activity
2.1 Unit Lesson, Unit Readings
3.1
3.2
Unit Lesson, Unit Readings
Reading Assignment
Chapter 5:
Environmental Pollutants and Their Fate
Chapter 6:
Dose and Response
Unit Lesson
This unit discusses the risks to the
environment from chemical contamination.
Historical incidents are explored in addition
to the factors that affect the fate of
chemicals in the environment. In the past, it
was thought that dilution was the solution to
pollution. Chemicals were released into the
environment, and it was thought that these
chemicals would just blow away until
researchers found persistent chemicals in
locations where they were not being used.
As this became known, new technologies
were invented to capture or reduce the
amount of chemicals.
Chemicals are found almost everywhere in
our environment. They enter our food chain
and can accumulate in animals. As
humans, we are at the top of the food
chain; breastfeeding infants is at the highest level. It has been theorized that infants are the most exposed
group to environmental contaminants.
UNIT III STUDY GUIDE
Environmental Risks
The pollution response unit at the Naval Air Station in Pensacola,
Florida., deploys oil containment booms at Sherman Cove to protect
environmentally sensitive grass beds from the Deepwater Horizon oil
spill on May 4, 2010.
(Nichols, 2010)
BOS 4201, Toxicology 2
UNIT x STUDY GUIDE
Title
Environmental Pollutants and Their Fate
Pollution is defined as any change in the characteristic of the air, water, or soil that will adversely affect the
health of an organism. A pollutant is any substance released into the environment that may cause adverse
effects. The ecosystem is complex with abiotic and biotic factors being interrelated. Pollutants are often
introduced into the ecosystem and carried into the atmosphere. Precipitation—in the form of rain, sleet, or
snow—can pull the pollutants from the atmosphere and deposit them onto land and into bodies of water,
causing contamination in the soil and water.
Below are some examples of common pollutants found in the environment:
gases (nitrogen oxides and sulphur dioxide),
metals (lead and mercury),
organics (benzene and toluene),
noise,
photochemical oxidants (ozone), and
radioactive wastes.
The fate of chemicals in the environment is affected by the process in which chemicals are moved and
transforme ...
An environmental hazard is a substance, a state or an event which has the potential to threaten the surrounding natural environment / or adversely affect people's health, and natural disasters such as storms and earthquakes.
Any single or combination of toxic chemical, biological, or physical agents in the environment, resulting from human activities or natural processes, that may impact the health of exposed subjects, including pollutants such as heavy metals, pesticides, biological contaminants, toxic waste, industrial and home chemicals.
Human-made hazards while not immediately health-threatening may turn out detrimental to man's well-being eventually, because deterioration in the environment can produce secondary, unwanted negative effects on the human ecosphere. The effects of water pollution may not be immediately visible because of a sewage system that helps drain off toxic substances. If those substances turn out to be persistent (e.g. persistent organic pollutant), however, they will literally be fed back to their producers via the food chain: plankton -> edible fish -> humans. In that respect, a considerable number of environmental hazards listed below are man-made (anthropogenic) hazards.
Hazards can be categorized in four types:
Chemical
Physical (mechanical, etc.)
Biological
Chemical hazards are defined in the Globally Harmonized System and in the European Union chemical regulations. They are caused by chemical substances causing significant damage to the environment. The label is particularly applicable towards substances with aquatic toxicity. An example is zinc oxide, a common paint pigment, which is extremely toxic to aquatic life.
In this Lecture will cover these Contents
1) Definition of environment
2) Components of environment
3) Environmental health
4) Environmental hazards
5) Human and Environment
6) Environment and technology
7) Improving Human Health & Environment
8) Major Environmental Problems in Somalia.
The USEPA defines biodegradation as a process by which microbial organisms transform or alter (through metabolic or enzymatic action) the structure of chemicals introduced into the environment.
According to the definition by the International Union of Pure and Applied Chemistry, the term biodegradation is “Breakdown of a substance catalyzed by enzymes in vitro or in vivo.
The term is often used in relation to ecology, waste management, biomedicine, and the natural environment (bioremediation) and is now commonly associated with environmentally friendly products that are capable of decomposing back into natural elements.
Biodegradable matter is generally organic material such as plant and animal matter and other substances originating from living organisms, or artificial materials that are similar enough to plant and animal matter to be put to use by microorganisms.
The American People's Dioxin Report - Resources for Healthy Children www.scribd.com/doc/254613619 - For more information, Please see Organic Edible Schoolyards & Gardening with Children www.scribd.com/doc/254613963 - Gardening with Volcanic Rock Dust www.scribd.com/doc/254613846 - Double Food Production from your School Garden with Organic Tech www.scribd.com/doc/254613765 - Free School Gardening Art Posters www.scribd.com/doc/254613694 - Increase Food Production with Companion Planting in your School Garden www.scribd.com/doc/254609890 - Healthy Foods Dramatically Improves Student Academic Success www.scribd.com/doc/254613619 - City Chickens for your Organic School Garden www.scribd.com/doc/254613553 - Huerto Ecológico, Tecnologías Sostenibles, Agricultura Organica www.scribd.com/doc/254613494 - Simple Square Foot Gardening for Schools - Teacher Guide www.scribd.com/doc/254613410 - Free Organic Gardening Publications www.scribd.com/doc/254609890 ~ chej.org
INTRODUCTION
Toxicology is the science of the poisons. It also studies the nature, effects, detection, assessment and treatment of their effects on biological material.
Toxicology is a multidisciplinary science. The ultimate objective of the combined research is to determine how an organism is affected by exposure to an agent.
This includes an understanding of:
How the agent moves and interact with living cells and tissues of the organism;
What parts of the organism are affected by its presence and health outcomes of this exposure.
Evaluation of the toxicity of substances whose biological effects may not have been well characterized.
The influence of chemical toxicity is mainly
determined by the dosage, duration of exposure,
route of exposure, species, age, sex, and environment.
The goal of toxicology is to contribute to the
general knowledge and harmful actions of
chemical substances.
2. to study their mechanisms of action,
3. and to estimate their possible risks to humans
HISTORY
Dioscorides, a Greek physician in the court of the Roman emperor Nero, made the first attempt to classify plants according to their toxic and therapeutic effect. Poisonous plants and animals were recognized and their extracts used for hunting or in warfare.
In 1500 BC people used hemlock, opium, arrow poisons, and certain metals to poison enemies or for state executions.
Theophrastus Phillipus Auroleus Bombastus von Hohenheim (1493–1541) (also referred to as Paracelsus, a Roman physician from the first century) is considered "the father" of toxicology.
He stated that "All things are poisonous and nothing is without poison; only the dose makes a thing not poisonous.“
Mathieu Orfila (1813) is considered the modern father of toxicology.
In 1850, Jean Stas became the first person to successfully isolate plant poisons from human tissue.
Hippolyte Visart de Bocarmé used nicotine to kill his brother-in-law. He extracted nicotine from tobacco leaves.
The 20th and 21st Centuries have marked by great advancements in the level of understanding of toxicology. DNA and various biochemicals that maintain body functions have been discovered. Our level of knowledge of toxic effects on organs and cells has expanded to the molecular level.
Some chemicals, both natural and man-made, can interfere with the hormonal system. They are called 'endocrine disruptors’. The most controversial issue is whether low level exposures to such chemicals can have adverse effects. Have endocrine disruptors affected wild life and our hormonal system? How much do we know so far?
5th International Disaster and Risk Conference IDRC 2014 Integrative Risk Management - The role of science, technology & practice 24-28 August 2014 in Davos, Switzerland
A xenobiotic is a chemical substance found within an organism that is not naturally produced or expected to be present within the organism.
It can also cover substances that are present in much higher concentrations than are usual.
Natural compounds can also become xenobiotics if they are taken up by another organism, such as the uptake of natural human hormones by fish found downstream of sewage treatment plant outfalls, or the chemical defenses produced by some organisms as protection against predators.
PPT EXPLAINS THE CONCEPT OF ECOTOXICOLOGY
SCOPE OF ECOTOXICOLOGY
PRINCIPLE OF ECOTOXICOLOGY
TYPES OF TOXIC SUBSTANCES
BIO-CHEMICAL BASIC TOXICITY
RECEPTOR MEDIATED TOXICITY
TYPES OF TOXICITY
SIGMOID RELATIONSHIP CURVE
COROLLARY OF TOXICOLOGY
ECOLOGICAL FACTORS AFFECTING TOXICITY
THANK YOU
The American People's Dioxin Report - Resources for Healthy Children www.scribd.com/doc/254613619 - For more information, Please see Organic Edible Schoolyards & Gardening with Children www.scribd.com/doc/254613963 - Gardening with Volcanic Rock Dust www.scribd.com/doc/254613846 - Double Food Production from your School Garden with Organic Tech www.scribd.com/doc/254613765 - Free School Gardening Art Posters www.scribd.com/doc/254613694 - Increase Food Production with Companion Planting in your School Garden www.scribd.com/doc/254609890 - Healthy Foods Dramatically Improves Student Academic Success www.scribd.com/doc/254613619 - City Chickens for your Organic School Garden www.scribd.com/doc/254613553 - Huerto Ecológico, Tecnologías Sostenibles, Agricultura Organica www.scribd.com/doc/254613494 - Simple Square Foot Gardening for Schools - Teacher Guide www.scribd.com/doc/254613410 - Free Organic Gardening Publications www.scribd.com/doc/254609890 ~ chej.org
INTRODUCTION
Toxicology is the science of the poisons. It also studies the nature, effects, detection, assessment and treatment of their effects on biological material.
Toxicology is a multidisciplinary science. The ultimate objective of the combined research is to determine how an organism is affected by exposure to an agent.
This includes an understanding of:
How the agent moves and interact with living cells and tissues of the organism;
What parts of the organism are affected by its presence and health outcomes of this exposure.
Evaluation of the toxicity of substances whose biological effects may not have been well characterized.
The influence of chemical toxicity is mainly
determined by the dosage, duration of exposure,
route of exposure, species, age, sex, and environment.
The goal of toxicology is to contribute to the
general knowledge and harmful actions of
chemical substances.
2. to study their mechanisms of action,
3. and to estimate their possible risks to humans
HISTORY
Dioscorides, a Greek physician in the court of the Roman emperor Nero, made the first attempt to classify plants according to their toxic and therapeutic effect. Poisonous plants and animals were recognized and their extracts used for hunting or in warfare.
In 1500 BC people used hemlock, opium, arrow poisons, and certain metals to poison enemies or for state executions.
Theophrastus Phillipus Auroleus Bombastus von Hohenheim (1493–1541) (also referred to as Paracelsus, a Roman physician from the first century) is considered "the father" of toxicology.
He stated that "All things are poisonous and nothing is without poison; only the dose makes a thing not poisonous.“
Mathieu Orfila (1813) is considered the modern father of toxicology.
In 1850, Jean Stas became the first person to successfully isolate plant poisons from human tissue.
Hippolyte Visart de Bocarmé used nicotine to kill his brother-in-law. He extracted nicotine from tobacco leaves.
The 20th and 21st Centuries have marked by great advancements in the level of understanding of toxicology. DNA and various biochemicals that maintain body functions have been discovered. Our level of knowledge of toxic effects on organs and cells has expanded to the molecular level.
Some chemicals, both natural and man-made, can interfere with the hormonal system. They are called 'endocrine disruptors’. The most controversial issue is whether low level exposures to such chemicals can have adverse effects. Have endocrine disruptors affected wild life and our hormonal system? How much do we know so far?
5th International Disaster and Risk Conference IDRC 2014 Integrative Risk Management - The role of science, technology & practice 24-28 August 2014 in Davos, Switzerland
A xenobiotic is a chemical substance found within an organism that is not naturally produced or expected to be present within the organism.
It can also cover substances that are present in much higher concentrations than are usual.
Natural compounds can also become xenobiotics if they are taken up by another organism, such as the uptake of natural human hormones by fish found downstream of sewage treatment plant outfalls, or the chemical defenses produced by some organisms as protection against predators.
PPT EXPLAINS THE CONCEPT OF ECOTOXICOLOGY
SCOPE OF ECOTOXICOLOGY
PRINCIPLE OF ECOTOXICOLOGY
TYPES OF TOXIC SUBSTANCES
BIO-CHEMICAL BASIC TOXICITY
RECEPTOR MEDIATED TOXICITY
TYPES OF TOXICITY
SIGMOID RELATIONSHIP CURVE
COROLLARY OF TOXICOLOGY
ECOLOGICAL FACTORS AFFECTING TOXICITY
THANK YOU
The Impact of Artificial Intelligence on Modern Society.pdfssuser3e63fc
Just a game Assignment 3
1. What has made Louis Vuitton's business model successful in the Japanese luxury market?
2. What are the opportunities and challenges for Louis Vuitton in Japan?
3. What are the specifics of the Japanese fashion luxury market?
4. How did Louis Vuitton enter into the Japanese market originally? What were the other entry strategies it adopted later to strengthen its presence?
5. Will Louis Vuitton have any new challenges arise due to the global financial crisis? How does it overcome the new challenges?Assignment 3
1. What has made Louis Vuitton's business model successful in the Japanese luxury market?
2. What are the opportunities and challenges for Louis Vuitton in Japan?
3. What are the specifics of the Japanese fashion luxury market?
4. How did Louis Vuitton enter into the Japanese market originally? What were the other entry strategies it adopted later to strengthen its presence?
5. Will Louis Vuitton have any new challenges arise due to the global financial crisis? How does it overcome the new challenges?Assignment 3
1. What has made Louis Vuitton's business model successful in the Japanese luxury market?
2. What are the opportunities and challenges for Louis Vuitton in Japan?
3. What are the specifics of the Japanese fashion luxury market?
4. How did Louis Vuitton enter into the Japanese market originally? What were the other entry strategies it adopted later to strengthen its presence?
5. Will Louis Vuitton have any new challenges arise due to the global financial crisis? How does it overcome the new challenges?
New Explore Careers and College Majors 2024.pdfDr. Mary Askew
Explore Careers and College Majors is a new online, interactive, self-guided career, major and college planning system.
The career system works on all devices!
For more Information, go to https://bit.ly/3SW5w8W
3. Ecotoxicology
• Introduction to Ecotoxicology
• Types of contaminants
• Sources of contaminants
• Nature ofToxicant
• Nature of man made chemicals
• Common types of environmental hazards
• Types ofToxicants or Pollutants
• Factors influencing toxicity
• Toxicity at organismic level
• Mapping environmental hazards
• Environmental toxicity testing
3 4/22/2021 Add a footer
4. 4 4/22/2021 Add a footer
•Ecotoxicology is the science devoted to the
study of the adverse effects of chemicals on
ecosystems structure, functions, and
biodiversity. It is a modern discipline, just
developed during the last four decades, directly
associated to the need to identify, predict,
control, and minimize the negative
environmental consequences of the recent
human industrial development.
Introduction to Ecotoxicology
5. Ecotoxicology has
always been connected
to toxicology, and is in
part an extension of
human/veterinary
toxicology to the
investigation of effects
on wildlife. In parallel,
ecotoxicology is also
linked to ecology, from
both conceptual and
methodological
viewpoints.
5 4/22/2021 Add a footer
7. Pollutant
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Pollutants are the elements,
molecules and particles
involved in pollution - life can
be harmed when exposed to
these materials, and the
effects of them on humans
and plants are well
known. Pollutants can be
introduced into the
environment in many ways,
both naturally and by humans.
8. Poison
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A poison is any substance that is
harmful to your body. You might
swallow it, inhale it, inject it, or
absorb it through your skin. Any
substance can be poisonous if too
much is taken. Poisons can include.
Prescription or over-the-counter
medicines taken in doses that are
too high.
9. Toxicant
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Toxicants are the man-made harmful
substances such as insecticides and many
other industrial chemicals which are
released to the environment by human
activities. Carcinogens, Mutagens,
Allergens, Neurotoxin and Endocrine
disrupters are the different types of
toxicants. Exposure to toxicants can have
long term health impacts among
organisms.
11. Sources of toxicants and Pollutants
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• Point source
• Non-point source
12. Point Source
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• Point sources release pollutants
from discrete conveyances, such
as a discharge pipe, and are
regulated by federal and state
agencies. The main point source
dischargers are factories and
sewage treatment plants, which
release treated wastewater.
• Location exactly known.
13. Non-point Source
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• Nonpoint source pollution is
a combination of pollutants from a
large area rather than from specific
identifiable sources such as
discharge pipes.
• Runoff is generally associated with
nonpoint source pollution, as water
is emptied into streams or rivers
after accumulating contaminants
from sources like gardens, parking
lots or construction sites.
14. Nature of toxicants
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A toxic agent is anything that can produce an adverse biological
effect. It may be chemical, physical, or biological in form. For
example, toxic agents may be:
• Chemical (such as cyanide)
• Physical (such as radiation)
• Biological (such as snake venom)
20. Types ofToxicants or Pollutants
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Organic
• Toxicants or Pollutants Polychlorinated Biphenyls
(PCBs) are organic that are still present in our
environment today despite being banned in many
countries such as the United States and Canada. Due
to the persistent nature of PCBs in aquatic
ecosystems, many aquatic species contain high levels
of this chemical.
• For example, fish farmed salmon have been shown to
have significantly higher PCB levels.
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Rout of Polychlorinated Biphenyls (PCBs)
22. 22 4/22/2021 Add a footer
Inorganic
Inorganic pollutants or toxicants comprise mainly of heavy metals,
which are toxic or poisonous even at low concentrations. Example of
heavy metals includes arsenic, mercury, lead, and chromium.They
can enter body system through water, food, and air and cause health
issues.
Some inorganic contaminants are as follow:
• Heavy metal
• pesticides
• Herbicides
• Insecticides
23. 23 4/22/2021 Add a footer
Heavy Metals
Heavy metals found in food sources, such as fish can also have
harmful effects. These metals can include mercury, lead, aluminum and
cadmium. It has been shown that fish are exposed to higher cadmium levels
and grow at a slower rate than fish exposed to lower levels or none.
Pesticides
Pesticides are a major source of environmental toxicity. These chemically
synthesized agents have been known to persist in the environment long
after their administration. The poor bio-degradability of pesticides can result
in bio-accumulation of chemicals in various organisms along with bio-
magnification within a food web. Pesticides can be categorized according to
the pests they target. Insecticides are used to eliminate agricultural pests
that attack various fruits and crops.
24. 24 4/22/2021 Add a footer
Herbicides
Herbicides target herbal pests such as weeds and other unwanted
plants that reduce crop production.
Insecticides
Dichlorodiphenyltrichloroethane (DDT) is an organochlorine
insecticide that has been banned due to its adverse effects on both
humans and wildlife. DDT was widely used by farmers in order to kill
agricultural pests. In 1962, the harmful effects of the widespread and
uncontrolled use of DDT were detailed by Rachel Carson in her book
The Silent Spring. Such large quantities of DDT and its metabolite
Dichlorodiphenyldichloroethylene (DDE) that were released into the
environment were toxic to both animals and humans.
25. Factors influencing toxicity
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Toxicity of a substance can be affected by many different
factors, such as the pathway of administration (whether the
toxicant is applied to the skin, ingested, inhaled, injected),
• The time of exposure (a brief encounter or long term),
• The number of exposures (a single dose or multiple doses
over time),
• The physical form of the toxicant (solid, liquid, gas), the
genetic makeup of an individual, an individual's overall
health, and many others.
26. 26 4/22/2021 Add a footer
Acute exposure
A single exposure to a toxic substance which may
result in severe biological harm or death; acute
exposures are usually characterized as lasting no
longer than a day.
Chronic exposure
Continuous exposure to a toxicant over an extended
period of time, often measured in months or years;
it can cause irreversible side effects.
29. Blood and Cardiovascular/CardiacToxicity
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Blood and Cardiovascular/CardiacToxicity results from xenobiotics acting
directly on cells in circulating blood, bone marrow, and the heart. Examples of
blood and cardiovascular/cardiac toxicity are:
• Hypoxia due to carbon monoxide binding of hemoglobin preventing
transport of oxygen.
• Decrease in circulating leukocytes due to chloramphenicol damage to bone
marrow cells.
• Leukemia due to benzene damage of bone marrow cells.
• Arteriosclerosis due to cholesterol accumulation in arteries and veins.
• Death of normal cells in and around the heart as a result
of exposure to drugs used to treat cancer.
30. DermalToxicity
30 4/22/2021 Add a footer
DermalToxicity can occur when a toxicant comes into direct contact
with the skin or is distributed to it internally. Effects range from
mild irritation to severe changes, such as irreversible
damage, hypersensitivity, and skin cancer. Examples of dermal
toxicity include:
• Dermal irritation from skin exposure to gasoline.
• Dermal corrosion from skin exposure to sodium hydroxide (lye).
• Dermal itching, irritation, and sometimes
painful rash from poison ivy, caused by urushiol.
• Skin cancer due to ingestion of arsenic or skin exposure to UV light.
31. Epigenetic Alterations
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Epigenetics is an emerging area in toxicology. In the field of
genetics, epigenetics involves studying how external or
environmental factors can switch genes on and off and change
the programming of cells.
More specifically, epigenetics refers to stable changes in the
programming of gene expression which can alter the phenotype
without changing the DNA sequence (genotype). Epigenetic
modifications include DNA methylation, covalent modifications
of histone tails, and regulation by non-coding RNAs, among
others.
Toxicants are examples of factors that can alter genetic
programming.
32. Eye toxicity
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EyeToxicity results from direct contact with or
internal distribution to the eye. Because the cornea and
conjunctiva are directly exposed to toxicants, conjunctivitis and
corneal erosion may be observed following
occupational exposure to chemicals. Many household items
can cause conjunctivitis. Chemicals in the circulatory system
can distribute to the eye and cause corneal opacity, cataracts,
and retinal and optic nerve damage. For example:
• Acids and strong alkalis may cause severe corneal corrosion.
• Corticosteroids may cause cataracts.
• Methanol (wood alcohol) may damage the optic nerve
33. Hepatotoxicity
33 4/22/2021 Add a footer
Hepatotoxicity is toxicity to the liver, bile duct, and gall bladder.
Because of its extensive blood supply and significant role in metabolism,
the liver is particularly susceptible to xenobiotics Thus, it is exposed to
high doses of the toxicant or its toxic metabolites. The primary forms
of hepatotoxicity are:
Steatosis Lipid accumulation in the hepatocytes.
Chemical hepatitis Inflammation of the liver.
Hepatic necrosis Death of the hepatocytes.
Intrahepatic cholestasis Backup of bile salts into the liver cells.
Cirrhosis Chronic fibrosis, often due to alcohol.
Hepatic cancer Cancer of the liver.
Hypersensitivity Immune reaction resulting in hepatic necrosis.
34. Immunotoxicity
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Immunotoxicity is toxicity of the immune system. It can take several forms:
• Hypersensitivity (allergy and autoimmunity)
• Immunodeficiency
• Uncontrolled proliferation (leukemia and lymphoma)
The normal function of the immune system is to recognize and defend against
foreign invaders.This is accomplished by production of cells that engulf and
destroy the invaders or by antibodies that inactivate foreign material.
Examples include:
• Contact dermatitis due to exposure to poison ivy.
• Systemic lupus erythematosus ("lupus") in workers exposed to
hydrazine.
• Immunosuppression by cocaine.
• Leukemia induced by benzene.
35. Nephrotoxicity
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The kidney is highly susceptible to toxicants because a high
volume of blood flows through the organ and it filters large
amounts of toxins which can concentrate in the kidney tubules.
Nephrotoxicity is toxicity to the kidneys. It can result in
systemic toxicity causing:
• Decreased ability to excrete body wastes.
• Inability to maintain body fluid and electrolyte balance.
• Decreased synthesis of essential hormones (for example,
erythropoietin, which increases the rate of
blood cell production).
37. Neurotoxicity
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Neurotoxicity represents toxicant damage to cells of
the central nervous system (brain and spinal cord) and
the peripheral nervous system (nerves outside
the CNS).The primary types of neurotoxicity are:
• Neuronopathies (neuron injury)
• Axonopathies (axon injury)
• Demyelination (loss of axon insulation)
• Interference with neurotransmission
38. ReproductiveToxicity
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ReproductiveToxicity involves toxicant damage to either the
male or female reproductive system.Toxic effects may cause:
• Decreased libido and impotence.
• Infertility.
• Interrupted pregnancy (abortion, fetal death, or premature
delivery).
• Infant death or childhood morbidity.
• Altered sex ratio and multiple births.
• Chromosome abnormalities and birth defects.
• Childhood cancer.
39. RespiratoryToxicity
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Respiratory Toxicity relates to effects on the upper respiratory system (nose,
pharynx, larynx, and trachea) and the lower respiratory
system (bronchi, bronchioles, and lung alveoli).The primary types of respiratory
toxicity are:
• Pulmonary irritation
• Asthma/bronchitis
• Reactive airway disease
• Emphysema
• Allergic alveolitis
• Fibrotic lung disease
• Pneumoconiosis
• Lung cancer
41. Mapping environmental hazards
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There are many environmental health mapping tools.
• TOXMAP is a Geographic Information System (GIS) from the
Division of Specialized Information Services of the United States
National Library of Medicine (NLM) that uses maps of the United
States to help users visually explore data from the United States
Environmental Protection Agency's (EPA)Toxics Release
Inventory and Superfund programs.
• TOXMAP is a resource funded by the US Federal Government.
TOXMAP's chemical and environmental health information is
taken from:
• NLM'sToxicology Data Network (TOXNET)
• PubMed
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Bio-monitoring is undertaken sometimes as
the “prelude to remediation.” Remediation
aims to remove potential toxic substances from
a contaminated site, thus restoring ecosystem
function as far as is reasonably possible
following the removal of the ecotoxicity by
biological, physical, or chemical means.
Bio-monitoring
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Molecular toxicology is the branch of toxicology (the study of the effects of
manifestly poisonous substances on individuals) that adopts
the biochemical approach to the understanding of the detrimental threats
to life, often recognized by a range of morbid conditions in a variety of
fauna and flora. Such pathology can be understood at a molecular level in
terms of biomolecular damage undergone by such macromolecules as DNA
(deoxyribonucleic acid: the genetic determinant mainly residing in the
nucleus of the living cell), RNA (ribo-nucleic acid: responsible for transfer of
the genetic message inherent in DNA structure sequence to the cytoplasm
of the cell), and diverse proteins constructed from a choice of sequence of
residues of 20 amino acids (obtained mainly from dietary protein hydrolysis
during digestion).
Molecular toxicology
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Environmental toxicity testing typically focuses on
organism-level endpoints such as:
• Mortality
• Growth
• Reproduction
risk assessment guidelines specify protection goals at
the level of the population and above.
Environmental toxicity
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One method of linking these different levels of biological
organization is the development of models that
extrapolate toxicant impacts at the individual level to
adverse outcomes at the population level. However,
annual population growth projections in highly fecund
species such as fathead minnow are subject to extreme
uncertainty.
46. End Points forVariousToxicity Studies
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Study End Points
Developmental toxicity
Fetus: mortality, growth retardation, skeletal variations,
gross external malformations, soft tissue/internal organ
defects
Female parent: general toxicity
ReproductiveToxicity
Male parent: general toxicity, effects on fertility,
reproductive organ changes
Offspring: effects on viability, sex ratio, growth, behavior
Carcinogenicity Tumor development and general toxicity
Neurotoxicity
Behavior, function, and motor activity deficits; microscopic
nervous tissue changes
Mutagenicity Heritable lesions leading to altered phenotypes
