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Lecture 1 2 ss-5
1. 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.
2. 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.
3. 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.
4. asweknowit.net
edtech2.boisestate.edu
Cells and Tissues of the Human Body
stephanierosebio156.blogspot.com
5. 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
6. 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
8. 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
9. 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.)
14. Health Outcomes From
Environmental Hazards
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)
15. 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
16. 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
17. 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.
18. 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
19. 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
20. 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
21.
22. 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
23. 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
24. The way by which a toxin enters the body is
referred to as the __________ of exposure
1. Magnitude
2. Route
3. Duration
4. Frequency
25. 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
26. 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.
27. 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.
28. Factors Influencing Toxicity
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
30. 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
31. 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.
32. Manifestation of Toxic Effects
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)
33. Manifestation of Toxic Effects
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.
34. 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.
Editor's Notes
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What’s an enzyme? What’s an effector organ?\n
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What does LD50 mean? \nLD stands for "Lethal Dose". LD50 is the amount of a material, given all at once, which causes the death of 50% (one half) of a group of test animals. The LD50 is one way to measure the short-term poisoning potential (acute toxicity) of a material. \nToxicologists can use many kinds of animals but most often testing is done with rats and mice. It is usually expressed as the amount of chemical administered (e.g., milligrams) per 100 grams (for smaller animals) or per kilogram (for bigger test subjects) of the body weight of the test animal. The LD50 can be found for any route of entry or administration but dermal (applied to the skin) and oral (given by mouth) administration methods are the most common. \nWhat does LC50 mean? \nLC stands for "Lethal Concentration". LC values usually refer to the concentration of a chemical in air but in environmental studies it can also mean the concentration of a chemical in water. \nFor inhalation experiments, the concentration of the chemical in air that kills 50% of the test animals in a given time (usually four hours) is the LC50 value. \n
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High Risk vs Low Risk\n
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Aflatoxin - Wikipedia, are naturally occurring mycotoxins that are produced by many species of Aspergillus, a fungus, most notably Aspergillus flavus and Aspergillus ...\n
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The liver is the largest gland in the body and performs an astonishingly large number of tasks that impact all body systems. One consequence of this complexity is that hepatic disease has widespread effects on virtually all other organ systems. At the risk of losing sight of the forest by focusing on the trees, we will focus on three fundamental roles of the liver:・Vascular functions, including formation of lymph and the hepatic phagocytic system.・Metabolic achievements in control of synthesis and utilization of carbohydrates, lipids and proteins.・Secretory and excretory functions, particularly with respect to the synthesis of secretion of bile.The latter is the only one of the three that directly affects digestion - the liver, through its biliary tract, secretes bile acids into the small intestine where they assume a critical role in the digestion and absorption of dietary lipids. However, understanding the vascular and metabolic functions of the liver is critical to appreciating the gland as a whole. [http://www.vivo.colostate.edu/hbooks/pathphys/digestion/liver/]\n
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Central Nervous System, Peripheral Nervous System\nAtaxia - affects on muscular movement\n
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Matrix: the intercellular substance of tissue\nBioavailability: The ability of a substance that enters the body to be liberated from its environmental matrix (water, tissue, soil) and to enter the circulation is referred to as Bioavailability\n