Lecture 1 2 ss-5

Toxicity
The amount of harm a chemical can cause is
toxicity.
Origin of “Toxic” is Greek for “bow” (toxon) where
arrows (shot by bows) were sometimes tipped with
poison.

Global production of chemicals was 1 million tons in
1930 and is now over 400 million tons.

How Poisons Work
 Poisons work by:-
 Changing the speed of different body functions
 Increase – heart rate, sweating
 Decrease – breathing, metabolism
 Steps involved in Poisoning
 Biochemical change
 e.g. inactivation of an enzyme
 Cellular change
 e.g. increase in nerve activity
 Physiological changes
 Signs and symptoms seen and felt in the effector organ
 Biochemical mechanism of action may be
specific or nonspecific.

Organization of
living things:
Atoms combine to
make molecules or
compounds which
combine to form an
organelle (a tiny
“organ” within the
cell); these combine
to produce enzymes,
create new cells,
build new tissue, etc.;
and groups of the
same kind of tissue
make up an organ;
then system then
organism.

asweknowit.net
edtech2.boisestate.edu

Cells and Tissues of the Human Body
stephanierosebio156.blogspot.com

What is the only cell in the body
that does not contain DNA?
1. Bone cell
2. Muscle cell
3. White blood cell
4. Red blood cell
5. Sperm or egg cell

LC50: Lethal
Concentration
test for acute
toxicity of
chemicals in
water and air.

Macromolecular Damage
 Toxicant Receptor: Macromolecule in body
with which toxicant interacts.
 Enzyme
 Membranes
 Proteins
 Nucleic acid – chronic effects
 Reactive compounds can damage cellular
proteins.
 Heavy metals – (sulfhydryl) denatures
proteins

Hazards in the Environment
Hazardous Substances may enter the environment
by:
1. Direct exposure to the source of contamination (e.g
Love Canal).
2. Direct discharge into air, water, or soil.
3. Inadequate landfills.
4. Environmental catastrophic events (e.g.: Donora,
Pa & Cuyahoga River,OH).
5. Ecologic catastrophic events (e.g.: algal blooms -
affecting ecosystems).
6. Dumping (roadside, forests, marshes, etc.)

Environmental Hazards
include medical waste dumping

include electronic waste dumping

include yard waste dumping

Characteristics of Hazardous
Exposure

1. Route – inhalation, ingestion,
dermal
2. Magnitude – concentration or dose
3. Duration – minutes, hours, days,
lifetime
4. Frequency – daily, weekly,
monthly, seasonally

Health Outcomes From
Carcinogenicity - (e.g from benzene)
Heritable genetic and
chromosomal mutations - (ionizing
radiation)
Developmental toxicity - (cadmium)
Reproductive toxicity - (lead)
Acute toxicity - (mustard gas)
Chronic toxicity - (carbon tetrachloride)
Neurotoxicity - (mercury)

Introduction to Toxicology
 Toxicology is the study of poisons.
 Science dealing with poisons and their effects
and with antidotes
 Toxic – poisonous
 Affected by or caused by a toxin or poison
(acting as a poison)
 Toxicant – poison or toxic agent
 Toxicity – how poisonous

Toxicity
 Toxic Agents

 Non-toxic Agents

 All substances can be toxic at the right
dose.

National Library of Medicine Toxicology Tutor:
http://sis.nlm.nih.gov/enviro/toxtutor.html

Environmental Science Activity

HPV Chemical Hazard Data Availability Study
Activity Part I Answer questions 1 - 17 in class

Activity Part II Answer Questions 1- 10 for homework.

Classes of Toxicants
 Air pollutants – volatile (or suspended
particles)
 Water pollutants – soluble or
suspensions/ emulsions
 Solid State Pollutants – soil or objects,
ie. Lead, radionucleides, UV
 Food Additives or contaminants
 Exposure in workplace
 Drugs – pharmaceuticals or abuse

Types of Toxicants
 Pesticides – Parathion, DDT, Chlordane
 Natural Toxicants – Aflatoxin (fungus)
 Organic Chemicals – solvents in paint,
glue, etc.
 Metals – lead, mercury (water or air)
 Physical Toxicants – asbestos, coal dust

Types of Effects
 Tissue or organ disruption:
 Neurological – direct nerve or neurotransmitter –
psychoactive compounds, metals
 Organ System – tissue destruction, chemical inhibition
(through protein interference)
 Teratogenic : defects in development and growth;
Mutagenic  Heritable genetic and chromosomal
mutation – ionizing radiation
 Carcinogenic: normal cells transform into cancer cells;
exposure to chemicals, tobacco, asbestos
 Reproductive: cervical cancer - Papilloma Virus. Prostate
cancer-It occurs when cells of the prostate mutate and
begin to multiply out of control.
 Hormone Disturbance: pituitary gland

General Toxicity Categories
 Respiratory
 System affected – nose, trachea, lungs
 Common symptoms – irritation, coughing, choking,
tight chest
 Gastrointestinal
 System affected – stomach, intestine
 Common symptoms - Nausea, vomiting, diarrhea
 Hepatic – Liver
 Main purifying organ of the body
 Renal
 System affected – kidney
 Common symptoms – back pain, urination

General Toxicity Categories
 Neurological
 System affected – CNS (brain & spinal cord), PNS
 Common symptoms – headache, dizziness, confusion,
depression, coma, convulsion, ataxia
 Hematological
 System affected – blood
 Common symptoms – anemia (tiredness, weakness)
 Dermatological
 System affected – skin, eye
 Common symptoms – rashes, itching, redness, swelling
 Reproductive
 System affected – ovaries, testes, fetus
 Common symptoms – infertility, miscarriage

The way by which a toxin enters the body is
referred to as the __________ of exposure
 

1. Magnitude
2. Route
3. Duration
4. Frequency

The human body functions as one whole system but we
need to also understand the parts that make up the
whole. The parts that make up all human body systems
are (in order):

1. chemical- tissue- cellular – organ – organ system
2. cellular – organ system - tissue- organ – chemical
3. tissue – organ system – chemical – organ – chemical
4. chemical – cellular – tissue- organ – organ system

What is homeostasis?
1 The ability of a system to regenerate blood cells.
2.The ability to maintain static electrical current within
the heart muscle.
3. The ability of a system or living organism to adjust its
internal environment to maintain a stable equilibrium.
4. The ability of starfish to regenerate its appendages.

Factors Influencing Toxicity
1. The TYPE OF AGENT
 Benign: normal environmental factors
 Therapeutic: aspirin, antibiotics, pharmaceuticals
 Toxic: harsh chemicals
2. The DOSE
 Toxicity is inversely related to dose: toxicity =1/
dose; the smaller the dose required to produce
the response, the more toxic is the chemical.

1. AGE
2. GENDER
3. CULTURE
4. PERSON – large vs small; active vs sedentary;
genetic predispositions
5. TIME AND FREQUENCY (DURATION) OF
EXPOSURE
6. NUTRITIONAL STATUS - diet and exercise???
7. HEALTH STATUS - healthy vs compromised

8. TARGET SYSTEM
 CNS – nerve, neurotransmitters (metals)
 Renal – kidney, (metals, polar compounds that
stay in the blood)
 Pulmonary – lung (air borne materials)
 Dermal – skin (contact agents)
 Hepatic – liver, (fat soluble material)
 Genotoxic – DNA, carcinogens, mutagens
9. ENVIRONMENT
 Temperature
 Light (cycle, intensity)
 Air (flow rate, humidity)

Types of Toxicity
 Acute
 Measured by the median lethal dose (LD50) observed
during the first fourteen days
 Dose that will kill 50 percent of a group of animals
under stated conditions
 Subacute
 Establish the minimal toxic and maximal tolerated
dose as well as the possible role of accumulation and
tolerance
 14 to 21 days
 Chronic
 Over 90 days
 Different doses

Manifestation of Toxic Effects
 Factors Affecting Bodily Processes
 External: extreme conditions?
 Internal: How the toxin enters the body:
Ingested, inhaled, or absorbed through
the skin.
 Types of physical effects seen or felt
(signs and symptoms) depend on the type
of stress to which the body has been
exposed.

 Common Non-specific Symptoms
 Headache
 Fever
 Nausea
 Vomiting
 Diarrhea
 Techniques used to diagnose the actual
causes of diseases
 Physical: detectable signs
 Biochemical: blood and urine tests
 Immunological: immune system (white blood cell
count)

 Homeostasis of the Body can be upset by:-
 Physical agents
 Chemical agents
 Biological agents
 Body’s reaction to stress depends on:-
 Nature of the agent
 Degree of stress
 Duration of stress
 Prolong and Intense stress result in failure of
homeostasis and eventual disease.

Toxic Effects
 Toxic effects can be either:-
 Reversible – cause no permanent damage
 Irreversible – cause permanent damage
 Poison can affect one or more organ
systems.
 Biochemical evidence is needed as
conclusive evidence of toxic exposure and
effect.

Lecture 1 2 ss-5

More Related Content

What's hot (20)

Viewers also liked (15)

Similar to Lecture 1 2 ss-5 (20)

Recently uploaded (20)

Lecture 1 2 ss-5

Editor's Notes