The document provides an overview of toxicology, defining it as the study of adverse chemical effects on living organisms. It details toxicity terminology, dose-response relationships, risk assessment, and risk management, alongside an extensive examination of various toxic metals, their sources, exposure effects, and associated health conditions. Key substances include arsenic, beryllium, cadmium, mercury, lead, nickel, copper, zinc, iron, and aluminum, each with unique risks and health implications.

1. Toxicology, and Disease
Causation. Poison.
Toxic Agent. Toxicity. Toxin.
Hazard Identification.
Risk Characterization. Risk
Management.

2. What is
Toxicology?
According to its traditional definition, toxicology is the science of poisons. A
more complete definition is “the study of the adverse effects of chemicals on
living organisms.”
Paracelsus (born Phillippus Theophrastus Aureolus Bombastus von
Hohenheim) is considered to be one of the founders of modern toxicology.
Mathieu Orfila authored a number of significant works, among them Trait des
poisons (1813).

3. History?
Paracelsus (born Phillippus Theophrastus
Aureolus Bombastus von Hohenheim) is
considered to be one of the founders of
modern toxicology.
Mathieu Orfila authored a number of
significant works, among them Trait des
poisons (1813).

4. Terminology
• A toxicologist is a scientist who has received extensive training in order to investigate in living organisms “the
adverse effects of chemicals and assess the probability of their occurrence.”
• The field of environmental toxicology is defined as the study of how ecological systems—their structure,
dynamics, function, etc.—are affected by pollutants.
• Xenobiotics are the chemical substances that are foreign to the biological system. They include naturally
occurring compounds, drugs, environmental agents, carcinogens, insecticides and etc.
• The term poison is “defined as any agent capable of producing a deleterious response in a biological system.
Virtually every known chemical has the potential to produce injury or death if it is present in a sufficient
amount.”
• The term toxic agent refers very generally to a material or factor that can be harmful to biological systems.
• Toxicity is defined as “the degree to which something is poisonous.” Toxicity is related to a material’s physical
and chemical properties. Some chemicals have low innate toxicity, while others have high toxicity.
• A material that has toxic properties is called a toxic substance. This substance can be a single toxic chemical
(e.g., arsenic, lead) or a mixture of toxic.
• A toxin usually refers to a toxic substance made by living organisms including reptiles, insects, plants, and
microorganisms.

5. THE CONCEPT OF A DOSE
AND RELATED TERMS.
• The term dose refers to “the amount of a substance administered
at one time.”In practice, dose often is expressed as a
concentration of a substance in the body, for example, the
concentration per milliliter (ml) of blood.
• Exposure is defined as “[p]roximity and/or contact with a source of
a disease agent in such a manner that effective transmission of the
agent or harmful effects of the agent may occur.”

6. Dose–Response Relationships
One of the most basic toxicologic concepts, a dose–response relationship, refers to a type of correlative relationship between
“the characteristics of exposure to a chemical and the spectrum of effects caused by the chemical.”
The term threshold refers to the lowest dose at which a particular response may occur.
(8) Pharmacodynamics - Part 2: Dose-response Relationship - YouTube

8. The concentration and toxicity of the chemical are affected by the following factors
• Route of entry into the body
• Received dose of the chemical
• Duration of exposure
• Interactions that transpire
among multiple chemicals
• Individual sensitivity

9. TOXICOLOGY AND RISK
ASSESSMENT
The term risk assessment refers to “a process
for identifying adverse consequences and
their associated probability.” Risk assessment
is “[t]he process of determining risks to health
attributable to environmental or other
hazards.”

10. Risk assessment
steps
(1) hazard identification
(2) dose–response
assessment
(3) exposure assessment
(4) risk characterization

11. Exposure assessment steps Risk Management
Risk management “consists of
actions taken to control
exposures to toxic chemicals in
the environment. Exposure
standards, requirements for
premarket testing, recalls of
toxic products, and outright
banning of very hazardous
materials are among the
actions that are used by
governmental agencies to
manage risk.

12. Toxic Metals and Elements.
Global chemical pollution

13. THE CERCLA PRIORITY LIST OF HAZARDOUS
SUBSTANCES
The Agency for Toxic Substances and Disease Registry (ATSDR) has developed a rank-ordered list of hazardous
substances, known as the CERCLA Priority List of Hazardous Substances. The acronym CERCLA refers to the
Comprehensive Environmental Response, Compensation, and Liability Act.

14. Classification of the Toxic Effects of Metals

15. Arsenic

16. Arsenic
• Arsenic in its pure form is a crystalline metalloid, an element
with properties that are intermediate between those of a metal
and a nonmetal. It is able to combine with other substances,
metallic and nonmetallic, and also to form stable organic
compounds.
• Arsenic exposure can come from many environmental sources,
including industrial processes that release arsenic, products that
contain arsenic, certain foods, and drinking water in some
geographic areas. Ingestion of 100 mg of arsenic produces acute
poisoning.
• Low-level chronic exposure to arsenic is associated with
melanosis, a dermatologic condition that can cause the
darkening of the skin of the entire body.
• Accumulated evidence suggests that arsenic is a carcinogen. It is
a cause of skin cancer when ingested and lung cancer when
inhaled. Ingestion of arsenic has been linked with internal
cancers such as bladder, kidney, and liver cancers.

17. Beryllium

18. Beryllium
Exposure to beryllium can result in the
disease berylliosis, also known as chronic
beryllium disease (CBD). This condition
can be extremely debilitating and in
some cases fatal. Two factors that affect
the development of CBD are beryllium
exposure itself and genetic susceptibility,
which has been shown to be associated
with a specific gene. Berylliosis is a form
of metal poisoning caused by inhalation
of beryllium dusts, vapors, or its
compounds or implantation of the
substance in the skin.

19. Cadmium

20. Cadmium
• Cadmium is found in all soils and rocks as well as coal and fertilizers derived from
minerals. Typically cadmium occurs as a mineral in combination with other
elements, such as oxygen.
• Health effects:
 Renal damage and renal dysfunction
 Bone disease
 Some forms of cancer
 Hypertension
 Cardiovascular diseases
 Genotoxicity
 Circulatory diseases
 Prostate and lung cancers
 Reproductive toxicity
 Reduced life expectancy
 Osteoporosis

21. Itai-itai disease
Itai-itai disease is caused by cadmium
(Cd) exposure, produced as a result of
human activities related to
industrialisation, and this condition was
first recognised in Japan in the 1960s.
Itai-itai disease is characterised by
osteomalaecia with severe bone pain
and is associated with renal tubular
dysfunction.

22. Mercury

23. Mercury
Minamata Disease is a poisoning disease that nervous system, mainly central
nervous system, is damaged by methylmercury. It is established that the
disease differs from inorganic mercury poisoning which damages kidneys, etc.,
and also, it isn't confirmed that it damages organs other than nervous system.

24. Lead Lead exposure is associated with serious central nervous
system effects and other adverse health consequences,
even when ingested at low levels. Lead poisoning is one
of the most common environmental pediatric health
problems in the United States. Especially damaging to the
growing neurologic systems of young children, lead is a
neurotoxin.

25. Nickel
• Classified as a heavy metal, nickel is
one of the constituents of the
earth’s crust. Because of its
omnipresence, human exposure to
low levels of nickel is probably
universal and unavoidable. Nickel
has a number of important qualities
that make it a valuable metal for use
in industry. Exposure can harm the
lungs, stomach, and kidneys.
Exposure to nickel may lead to
cancer. Workers may be harmed
from exposure to nickel.

26. Copper

27. Copper
• Although copper is an essential nutritional element, at higher levels it
is known to produce toxic effects. Exposure to concentrated amounts
of copper (far above trace levels) can produce respiratory and
gastrointestinal disturbances. The respiratory effects from copper
dust include irritation of the respiratory tract (e.g., nose and mouth).
The gastrointestinal effects associated with ingestion of copper
include vomiting, diarrhea, nausea, and stomach cramping. Very high
levels of copper are known to cause liver damage, renal damage, and
death. Although it is associated with toxic effects, copper has not
been classified as a human carcinogen.

28. Zinc and Iron
• Excessive levels of zinc exposure, which can have toxic
effects, result from the ingestion of contaminated food and
water and from inhalation of zinc dusts in occupational
environments. Excessive amounts of zinc, defined as
beginning at 10 to 15 times the levels required to maintain
health, are thought to affect the normal functioning of
blood-forming organs, biochemical processes, and the
endocrine system.
• Iron has the capacity to accumulate in the body, because
little is excreted during metabolic processes. The disease
known as hemachromatosis is associated with iron toxicity
from excessive buildup of iron. Excessive amounts of iron
can have toxic effects, such as vomiting, diarrhea, and
damage to the intestines. Iron toxicity also may produce
low blood pressure, lethargy, neurologic effects including
seizures, and liver injury.

29. Aluminum
Aluminum has been studied as a factor that
may be linked to Alzheimer’s disease.
Aluminum is known to be a powerful
neurotoxicant. The role of aluminum as a
factor in the pathogenesis of Alzheimer’s
disease remains unconfirmed.

30. Questions?