Transcript Science Fair Project - Somerset Area School District

Chapter 8
Toxicology:
Poisons and Alcohol
“All substances are poisons.
There is none which is not.
The right dose differentiates
a poison and remedy.”
—Paracelsus (1495-1541). Swiss
physician and chemist
Toxicology and Alcohol
Students will learn:
 A quantitative approach to
toxicology.
 The danger of using alcohol.
Chapter 8
Kendall/Hunt Publishing Company
1
Toxicology and Alcohol
Students will be able to:






Chapter 8
Discuss the connection of blood alcohol
levels to the law, incapacity, and test
results.
Understand the vocabulary of poisons.
Design and conduct scientific
investigations.
Use technology and mathematics to
improve investigations and
communications.
Identify questions and concepts that guide
scientific investigations.
Communicate and defend a scientific
argument.
Kendall/Hunt Publishing Company
2
Was Paracelsus Right?
 Hormesis —refers to the concept
promoted by Paracelsus: that substances
that kill at high doses are actually
beneficial at low doses— the poison is in
the dosage.
 This appears to be true for many substances:
oxygen, water, aspirin, alcohol, etc.
Chapter 8
Kendall/Hunt Publishing Company
3
Historical Perspective
of Poisoners




Olympias—a famous Greek poisoner
Locusta—personal poisoner of Emperor Nero
Lucretia Borgia—father was Pope Alexander VI
Madame Giulia Toffana—committed over 600
successful poisonings, including two Popes.
 Hieronyma Spara—formed a society to teach women
how to murder their husbands
 Madame de Brinvilliers and Catherine Deshayes—
French poisoners.
AND many others through modern times.
Chapter 8
Kendall/Hunt Publishing Company
4
People of Historical Significance
Mathieu Orfila—known as
the father of forensic
toxicology, published in
1814 “Traite des Poisons”
which described the first
systematic approach to the
study of the chemistry and
physiological nature of
poisons.
Chapter 8
Kendall/Hunt Publishing Company
5
Toxicology
Toxicology —the study of the adverse effects of chemicals
or physical agents on living organisms.
Types:
 Environmental Toxicology—air, water, soil
 Consumer Toxicology—foods, cosmetics, drugs
 Medical (Clinical) Toxicology—prescription
medication
 Forensic Toxicology —use of toxicology to aid in the
investigation of death, poisoning and drug use.
Chapter 8
Kendall/Hunt Publishing Company
6
Forensic Toxicology
 Postmortem—medical examiner or
coroner
 Criminal—motor vehicle accidents (MVA)
 Workplace—drug testing
 Sports—human and animal
 Environment—industrial, catastrophic,
terrorism
Chapter 8
Kendall/Hunt Publishing Company
7
Toxins
 Toxin—a substance that causes injury to
the health of a living thing on contact or
absorption, typically by interacting with
enzymes and receptors. (Usually a
naturally produced substance that kills
rapidly in small quantities)
Chapter 8
Kendall/Hunt Publishing Company
8
Toxic Substances
Toxic substances may:
 Be a cause of death
 Contribute to death
 Cause impairment
 Explain behavior
Poison hemlock is a plant
related to the carrot. It contains
alkaloids that negatively affect
the nervous system
Chapter 8
Kendall/Hunt Publishing Company
9
The Severity of the Problem
“If all those buried in our cemeteries who
were poisoned could raise their hands,
we would probably be shocked by the
numbers.”
—John Harris Trestrail, “Criminal Poisoning”
Chapter 8
Kendall/Hunt Publishing Company
10
Elements of Toxicity
 Dosage
 many substances are only lethal in high dosages
 The chemical or physical form of the substance
 Arsenic is not very poisonous in its natural form (metal);
but arsenic trioxide or arsenic gas is very poisonous.
 The mode of entry into the body
 some substances are most poisonous if swallowed;
others must be injected, inhaled or absorbed
Chapter 8
Kendall/Hunt Publishing Company
11
Elements of Toxicity
 Body weight and physiological conditions of the victim,
including age and sex
 Blood alcohol content is directly related to body weight
 Infants and elderly are more susceptible to most toxins
 The time period of exposure
 Sometimes small amounts ingested over time create a
tolerance for the toxin
 Chronic exposure (larger amounts over time) can create serious
medical problems
 Acute toxicity—very large dose causing immediate problems,
including death
Chapter 8
Kendall/Hunt Publishing Company
12
Elements of Toxicity
 The presence of other chemicals in the
body or in the dose
 Synergism: combination of two chemicals
increases the effects of both in the system
Ex: antihistamine and alcohol
 Antagonism: combination of two chemicals
decreases the effects of both in the system
Ex: Chelating agent and arsenic
Chapter 8
Kendall/Hunt Publishing Company
13
Lethal Dose
 LD50 —refers to the dose of a substance that kills half
the test population, usually within four hours
 (Note: test population is usually mice or rats)
 Expressed in milligrams of substance per kilogram of
body weight. A correlation is then made to humans
based on the body weight data.
 However, estimating lethal doses for humans is often
complicated by the fact that resistance to certain
chemicals can differ greatly between species
Chapter 8
Kendall/Hunt Publishing Company
14
Toxicity Classes
LD50 (rat,oral)
Correlation to Ingestion
by 150 lb Adult Human
Toxicity
<1mg/kg
a taste to a drop
extremely
1-50 mg/kg
to a teaspoon
highly
50-500 mg/kg
to an ounce
moderately
500-5000 mg/kg
to a pint
slightly
5-15 g/kg
to a quart
practically non-toxic
Over 15g/kg
more than 1 quart
relatively harmless
Chapter 8
Kendall/Hunt Publishing Company
15
LD50 Update
 Because a single test may kill as many as
100 animals, the U.S. and other members
of the Organization for Economic
Cooperation and Development agreed in
December 2000 to phase out the LD50 test
in favor of alternatives that greatly reduce
(or even eliminate) deaths of the test
animals.
Chapter 8
Kendall/Hunt Publishing Company
16
Federal Regulatory Agencies
 To ensure public safety, the federal government has
created several regulatory agencies related to toxic
substances:
 Food and Drug Administration (FDA)—deals with
pharmaceuticals, food additives, and medical devices
 Environmental Protection Agency (EPA)—works with
agricultural and industrial chemicals released to the environment
 Consumer Product Safety Commission—concerned with
toxins in consumer products
 Department of Transportation (DOT)—watches shipment of
toxic chemicals
 Occupational Safety and Health Administration (OSHA)—
concerned with exposure to chemicals in the workplace
Chapter 8
Kendall/Hunt Publishing Company
17
Symptoms of Various Types
of Poisoning
Type of Poison
Symptom/Evidence
 Caustic Poison (lye)
Characteristic burns around the lips and
mouth of the victim
Red or pink patches on the chest and thighs,
unusually bright red lividity
Black vomit
Greenish-brown vomit
Yellow vomit
Coffee brown vomit. Onion or garlic odor
Burnt almond odor
Pronounced diarrhea
Nausea and vomiting, unconsciousness,
possibly blindness
 Carbon Monoxide







Sulfuric acid
Hydrochloric acid
Nitric acid
Phosphorous
Cyanide
Arsenic, Mercury
Methyl (wood) or
Isopropyl (rubbing) alcohol
Chapter 8
Kendall/Hunt Publishing Company
18
Critical Information
on Poisons










Form
Common color
Characteristic odor
Solubility
Taste
Common sources
Lethal dose
Mechanism
Possible methods of administration
Time interval of onset of
symptoms.
Chapter 8
 Symptoms resulting from an acute
exposure
 Symptoms resulting from chronic
exposure
 Disease states mimicked by
poisoning
 Notes relating to the victim
 Specimens from victim
 Analytical detection methods
 Known toxic levels
 Notes pertinent to analysis of
poison
 List of cases in which poison was
used
—John Trestrail from “Criminal Poisoning”
Kendall/Hunt Publishing Company
19
To Prove a Case







Prove a crime was committed
Motive
Intent
Access to poison
Access to victim
Death was caused by poison
Death was homicidal
Chapter 8
Kendall/Hunt Publishing Company
20
Forensic Autopsy
Look for:
 Irritated tissues
 Characteristic odors
 Mees lines—single transverse
white bands on nails.
Order toxicological screens
 Postmortem concentrations should be done at the
scene for comparison
 No realistic calculation of dose can be made from a
single measurement
21
Chapter 8
Kendall/Hunt Publishing Company
Human Specimens for Analysis
 Blood
 Urine
 Vitreous Humor of
Eyes
 Bile
 Gastric contents
Chapter 8
 Liver tissue
 Brain tissue
 Kidney tissue
 Hair/nails
Kendall/Hunt Publishing Company
22
Alcohol—Ethyl Alcohol (C2H5OH)






Most abused drug in America
About 40% of all traffic deaths are alcohol-related
Toxic—affecting the central nervous system, especially the brain
Colorless liquid, generally diluted in water
Acts as a depressant
Alcohol appears in blood within minutes of consumption; 30-90
minutes for full absorption
 Detoxification—about 90% is done in the liver at a rate of about
0.015% per hour.
 About 5% is excreted unchanged in breath, perspiration and urine
Chapter 8
Kendall/Hunt Publishing Company
23
Rate of Absorption
Depends on:
 amount of alcohol consumed
 the alcohol content of the beverage
 time taken to consume it
 quantity and type of food present in the
stomach
 physiology of the consumer
Chapter 8
Kendall/Hunt Publishing Company
24
BAC
Blood Alcohol Content
 Expressed as percent weight per volume of blood
 Legal limits in all states is 0.08% (0.08 grams of pure
alcohol for every 100ml of blood)
 Parameters influencing BAC:




Chapter 8
Body weight
Alcoholic content
Number of beverages consumed
Time between consumption
Kendall/Hunt Publishing Company
25
BAC
 Burn off rate of 0.015% per hour but can
vary:
 Male
BAC male = 0.071 x (oz) x (% alcohol)
body weight
 Female
BAC female = 0.085 x (oz) x (% alcohol)
body weight
Chapter 8
Kendall/Hunt Publishing Company
26
Sample Problem
 What would be the approximate BAC of a 185 pound man who
has consumed three shots (1.5 oz.each) of Jack Daniels
(80 proof = 40% alcohol) in an hour?
BACmale = 0.071 x 4.5 x 40 = 0.07
185
Chapter 8
Kendall/Hunt Publishing Company
27
Henry’s Law
 Henry’s Law provides the scientific basis for the breath test check for
sobriety.
 When a volatile chemical is dissolved in a liquid and is brought to
equilibrium with air, there is a fixed ratio between the concentration
of the volatile compound in the air and its concentration in the liquid;
this ratio is constant for a given temperature. THEREFORE, the
concentration of alcohol in breath is proportional to that in the
blood.
 This ratio of alcohol in the blood to alcohol in the alveolar air is
approximately 2100 to 1. In other words 1 ml of blood will contain
nearly the same amount of alcohol as 2100 ml of breath.
Chapter 8
Kendall/Hunt Publishing Company
28
Field Tests
 Preliminary tests—used to determine the degree of
suspect’s physical impairment and whether or not
another test is justified.
 Psychophysical tests—3 Basic Tests
 Horizontal gaze nystagmus (HGN): follow a pen or small
flashlight, tracking left to right with one’s eyes. In general,
wavering at 45 degrees indicates 0.10 BAC.
 Nine Step walk and turn (WAT): comprehend and execute
two or more simple instructions at one time.
 One-leg stand (OLS): maintain balance, comprehend and
execute two or more simple instructions at one time.
Chapter 8
Kendall/Hunt Publishing Company
29
The Breathalyzer




Invented in 1954
More practical in the field
Collects and measures alcohol content of alveolar breath
Breath sample mixes with 3 ml of 0.025 % K2Cr2O7 in sulfuric
acid and water
2K2Cr2O7 + 3C 2H5OH + 8H 2SO4  2Cr2(SO4)3 + 2K2SO4 + 3CH3COOH + 11 H2O
 Potassium dichromate is yellow, as concentration decreases its
light absorption diminishes so the breathalyzer indirectly
measures alcohol concentration by measuring light
absorption of potassium dichromate before and after the
reaction with alcohol
Chapter 8
Kendall/Hunt Publishing Company
30
Generalizations
 During absorption, the concentration of alcohol in arterial
blood will be higher than in venous blood.
 Breath tests reflect alcohol concentration in the
pulmonary artery.
 The breathalyzer also can react with acetone (as found
with diabetics), acetaldehyde, methanol, isopropyl alcohol,
and paraldehyde, but these are toxic and their presence
means the person is in serious medical condition.
 Breathalyzers now use an infrared light absorption
device with a digital read-out. Prints out a card for a
permanent record.
Chapter 8
Kendall/Hunt Publishing Company
31
People in the News
John Trestrail is a practicing toxicologist
who has consulted on many criminal
poisoning cases. He is the founder of the
Center for the Study of Criminal Poisoning
in Grand Rapids, Michigan which has
established an international database to
receive and analyze reports of homicidal
poisonings from around the world. He is
also the director of DeVos Children’s
Hospital Regional Poison Center. In
addition, he wrote the book, Criminal
Poisoning, used as a reference by law
enforcement, forensic scientists and
lawyers.
Chapter 8
Kendall/Hunt Publishing Company
32
More Information
Read more about Forensic Toxicology from
Court TV’s Crime Library at:
http://www.crimelibrary.com/criminal_mind/forensic
s/toxicology/2.html
Chapter 8
Kendall/Hunt Publishing Company
33