Toxicology
1. Toxicology—the study of the
adverse effects of chemicals or
physical agents on living
organisms
1. Types:
• Environmental—air, water,
soil
• Consumer—foods,
cosmetics, drugs
• Medical, clinical, forensic
Forensic Toxicology
1)
2)
3)
4)
5)
Postmortem—medical
examiner or coroner
Criminal—motor vehicle
accidents (MVA)
Workplace—drug testing
Sports—human and animal
Environment—industrial,
catastrophic, terrorism
Toxicology
Toxic substances may:
1. Be a cause of death
2. Contribute to death
3. Cause impairment
4. Explain behavior
Historical Perspective of Poisoners
1. Olympias—a famous Greek poisoner
2. Locusta—personal poisoner of
Emperor Nero
3. Lucretia Borgia—father was Pope
Alexander VI
4. Madame Giulia Toffana—committed
over 600 successful poisonings,
including two popes
5. Hieronyma Spara—formed a society to
teach women how to murder their
husbands
6. Madame de Brinvilliers and Catherine
Deshayes—French poisoners.
People of Historical Significance
Mathieu Orfila—known as the father of
forensic toxicology, published in
1814 Traité des poisons which
described the first systematic
approach to the study of the
chemistry and physiological nature of
poisons
Aspects of Toxicity
1. Dosage
2. The chemical or physical form
of the substance
3. The mode of entry into the
body
4. Body weight and physiological
conditions of the victim,
including age and sex
5. The time period of exposure
6. The presence of other
chemicals in the body or in the
dose
Lethal Dose
1. LD50 refers to the dose of a
substance that kills half the test
population, usually within four
hours
2. Expressed in milligrams of
substance per kilogram of body
weight
Toxicity Classification
LD50 (rat,oral)
Correlation to
Ingestion by 150-lb
Adult Human
Toxicity
<1 mg/kg
a taste to a drop
extreme
1–50 mg/kg
to a teaspoon
high
50–500 mg/kg
to an ounce
moderate
500–5,000 mg/kg
to a pint
slight
5–15 g/kg
to a quart
practically nontoxic
Over 15 g/kg
more than 1 quart
relatively harmless
Federal Regulatory Agencies
1.
2.
3.
4.
5.
Food and Drug Administration (FDA)
Environmental Protection Agency (EPA)
Consumer Product Safety Commission
Department of Transportation (DOT)
Occupational Safety and Health Administration
(OSHA)
Summary Questions:
Read p. 208-214
1)What is Clostridium botulinum commonly used for today?
2)Explain hormesis?
3)How was Socrates poisoned?
4)What were the common poisons during the European Renaissance?
5)What was the importance of Mathieu Orfila’s 1814 book “Traite des poisons”?
6)Explain how the Marsh test was used in the 1840 trial of Marie Lafarge.
7)Define chronic exposure.
8)Define acute toxicity.
9)How does synergism affect a substance?
10)How does antagonism affect a substance?
11)A lady is lying in bed & she is dead. Beside her is a pool of liquid & two pieces of wood. How did she
die?
12)Why is estimating lethal doses in humans very difficult?
13)What is the lethal dose of nicotine in humans? Dogs?
14)In Dec. 2004, how was Viktor Yushchenko (Ukranian Presidential candidate) poisoned?
15)What is the LD50 in humans for Clostridium botulinum?
16)Explain how Aleksandr Litvinenko was poisoned KGB operatives.
17)What are some of the influences on the effect of poisons and toxins on the body?
18)Why does arsenic accumulate in hair and fingernails?
19)What is the LD50 of table salt for a 180-lb man? What would it be for MgCl2 (epson salt)? For NiCl2? Why
is there such a difference?
20)What is LD100?
Lead Poisoning:
1. Lead compounds are not highly
poisonous. But chronic exposure
to lead poses a real health
problem.
2. Most common exposure is
contact with lead-based paints
(Banned in 1978).
3. Lead-based paints taste sweet.
A teething child will often lick and
chew the paint.
Symptoms of Various Types of Poisoning
Type of Poison
Symptom/Evidence
Caustic Poison (lye)
Burns around lips & mouth of victim
Carbon monoxide
Red or pink patches on chest & thigh,
unusually bright red lividity
Sulfuric acid
Black vomit
Hydrochloric acid
Greenish-brown vomit
Nitric acid
Yellow vomit
Phosphorus
Coffee-brown vomit, onion or garlic odor
Cyanide
Burnt almond odor
Arsenic, mercury
Extreme diarrhea
Methyl (wood) or isopropyl
(rubbing) alcohol
Nausea & vomiting, unconsciousness,
blindness
Critical Information
1.
2.
3.
4.
5.
6.
7.
8.
9.
Form
Common color
Characteristic odor
Solubility
Taste
Common sources
Lethal dose
Mechanism
Possible methods of
administration
10. Time interval of onset of
symptoms
11. Symptoms resulting from
an acute exposure
12. Symptoms resulting from
chronic exposure
13. Disease states mimicked
by poisoning
14. Notes relating to the victim
15. Specimens from victim
16. Analytical detection
methods
17. Known toxic levels
18. Notes pertinent to analysis
of poison
19. List of cases in which
poison was used
To Prove a Case
1.
Prove a crime was committed
2.
Motive
3.
Intent
4.
Access to poison
5.
Access to victim
6.
Death was homicidal
7.
Death was caused by poison
Forensic Autopsy
1. Look for:
• Irritated tissues
• Characteristic odors
• Mees lines—single transverse white
bands on nails
2. 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.
Human Specimens for Analysis
1.
2.
3.
4.
5.
6.
7.
8.
9.
Blood
Urine
Vitreous humor of eyes
Bile
Gastric contents
Liver tissue
Brain tissue
Kidney tissue
Hair/nails
Summary Questions:
Read p. 214-219
1)
2)
3)
4)
How can you determine whether there is lead in paint?
What are three other sources of lead in the everyday environment?
Describe how Georgi Markov was killed? What did his autopsy reveal?
Some elements are naturally radioactive; that is they have either no stable isotopes or
have one or more radioactive isotopes. List three common ones.
5) What are the three types of particles emitted by radioactive substances? Which one is
stopped most easily? Why?
6) Would Litvinenko have died if he had merely spilled tea laced with Po-210 on his shirt?
Alcohol - Ethyl Alcohol (C2H5OH)
1.
2.
3.
4.
5.
6.
7.
8.
Most abused drug in America
About 40 percent 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 percent in the
liver
About 5 percent is excreted
unchanged in breath, perspiration, and
Rate of Absorption
Depends on:
1. Amount of alcohol consumed
2. The alcohol content of the
beverage
3. Time taken to consume it
4. Quantity and type of food
present in the stomach
5. Physiology of the consumer
BAC: Blood Alcohol Content
1.
Expressed as percent weight
per volume of blood
2.
Legal limit in all states is 0.08
percent
3.
Parameters influencing BAC:
•
Body weight
•
Alcohol content
•
Number of beverages
consumed
•
Time since consumption
BAC Calculation
Burn-off rate of 0.015 percent per hour, but can vary:
Male
BAC = 0.071  (oz)  (% alcohol)
body weight
Female
BAC = 0.085  (oz)  (% alcohol)
body weight
Henry’s Law
1. 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.
2. This ratio of alcohol in the blood to alcohol in the alveolar
air is approximately 2,100 to 1. In other words, 1 ml of
blood will contain nearly the same amount of alcohol as
2,100 ml of breath.
Field Tests
1. Preliminary tests—used to
determine the degree of
suspect’s physical
impairment and whether or
not another test is justified
2. Psychophysical tests—
three 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
The Breathalyzer
1.
2.
3.
4.
More practical in the field
Collects and measures alcohol content of
alveolar breath
Breath sample mixes with 3 ml of 0.025
percent K2Cr2O7 in sulfuric acid and water:
2K2Cr2O7 +3C2H5OH + 8H2SO4 
2Cr2(SO4)3 + 2K2SO4 + 3CH3COOH +
11H2O
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.
5.
6.
7.
8.
During absorption, the concentration of alcohol in
arterial blood is higher than in venous blood.
Breath tests reflect alcohol concentration in the
pulmonary artery.
The breathalyzer also can react with acetone (as
found in 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 readout. Prints out a card for a
permanent record.
Summary Questions:
Read p. 220-225.
1)Define DUI?
2)What is the rate of absorption of alcohol dependent upon?
3)What is the BAC limit for alcohol?
4)How much alcohol is metabolized in the liver?
5)What is alcohol’s average rate of removal from the body?
6)How do you calculate BAC for a male? Female?
7)Define Henry’s Law.
8)What would be the BAC of a 160-lb male who has consumed 2 pints (16 oz each) of beer (5% alcohol) in 1
hour?
9)What is the distribution of alcohol between blood and air expelled deeply from the lungs?
10)What does the Nystagmus test show for an intoxicated person?
11)About how much total alcohol would you expect to find in the blood of a 110-lb woman with a BAC of 0.04?
12)Calculate how much blood the woman above has in her body. Show your work.
13)What would be the BAC of a 136-lb woman who has consumed three vodka tonics (2 oz. of vodka each,
with vodka at 80 proof) during her lunch hour? If she forgets the time and talks for two more hours with her
friend without having another drink, what will her BAC be when she gets back to work?
14)A 165-lb man was involved in a car accident at 10 PM. His BAC was measured at the time at 0.08, which
he said was impossible because he had only two beers (pint-size, 5% alcohol) just after work at 6 PM. How
many beers did he actually have?