chapter 8 toxicology: poisons and alcohol
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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
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Toxicology
Definition—the study of the adverse effects of chemicals or physical agents on living organisms.
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Toxicology
Types:Environmental—air, water, soilConsumer—foods, cosmetics, drugs
Medical, clinical, forensic
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Forensic Toxicology
Postmortem—medical examiner or coroner
Criminal—motor vehicle accidents (MVA)
Workplace—drug testing
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Forensic Toxicology
Sports—human and animalEnvironment—industrial,
catastrophic, terrorism
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Toxicology
Toxic substances may: Contribute to death Be a cause of death Cause impairment Explain behavior
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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”
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Aspects of ToxicityDosageThe chemical or physical form of the
substanceThe mode of entry into the bodyBody weight and physiological
conditions of the victim, including age and sex
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Aspects of Toxicity
The time period of exposureThe presence of other
chemicals in the body or in the dose
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Lethal Dose
LD50—refers to the dose of a substance that kills half the test population, usually within four hours
Expressed in milligrams of substance per kilogram of body weight
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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
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Federal Regulatory Agencies
Food and Drug Administration (FDA)
Environmental Protection Agency (EPA)
Consumer Product Safety Commission
Department of Transportation (DOT)
Occupational Safety and Health Administration (OSHA)
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Symptoms of Various Typesof Poisoning
Type of Poison Symptom/Evidence Caustic Poison (lye) Characteristic burns
around the lips and mouth of the victim
Carbon Monoxide Red or pink patches on the chest and thighs,
unusually bright red lividity Sulfuric acid Black vomit Hydrochloric acid Greenish-brown vomit Nitric acid Yellow vomit
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Symptoms of Various Typesof Poisoning
Type of Poison Symptom/Evidence
Phosphorous Coffee brown vomit. Onion or garlic odor
Cyanide Burnt almond odor Arsenic, Mercury Pronounced diarrhea Methyl (wood) or Nausea and vomiting,
Isopropyl (rubbing) unconsciousness, alcohol possibly blindness
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Critical Informationon Poisons
FormCommon colorCharacteristic odorSolubilityTasteCommon sources
—John Trestrail from “Criminal Poisoning”
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Critical Informationon Poisons
MechanismPossible methods of administrationTime interval of onset of symptoms.Symptoms resulting from an acute
exposureSymptoms resulting from chronic
exposure
—John Trestrail from “Criminal Poisoning”
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Critical Informationon Poisons
Disease states mimicked by poisoning
Notes relating to the victimSpecimens from victimAnalytical detection methods
—John Trestrail from “Criminal Poisoning”
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Critical Informationon Poisons
Known toxic levelsNotes pertinent to analysis
of poisonList of cases in which
poison was used—John Trestrail from “Criminal Poisoning”
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To Prove a Case
Prove a crime was committed Motive Intent Access to poison
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To Prove a Case
Access to victim Death was caused by
poison Death was homicidal
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Forensic Autopsy
Look for:
Irritated tissues
Characteristic odors
Mees lines—single transverse white bands on nails.
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Forensic Autopsy
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
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Human Specimens for Analysis
Blood
Urine
Vitreous Humor of Eyes
Bile
Gastric contents
Liver tissue
Brain tissue
Kidney tissue
Hair/nails
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Alcohol—Ethyl Alcohol (C2H5OH)
Most abused drug in AmericaAbout 40% of all traffic deaths
are alcohol-relatedToxic—affecting the central
nervous system, especially the brain
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Alcohol—Ethyl Alcohol (C2H5OH)
Colorless liquid, generally diluted in water
Acts as a depressantAlcohol appears in blood within
minutes of consumption; 30-90 minutes for full absorption
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Alcohol—Ethyl Alcohol (C2H5OH)
Detoxification—about 90% in the liver
About 5% is excreted unchanged in breath, perspiration and urine
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Rate of AbsorptionDepends on:
amount of alcohol consumedthe alcohol content of the beveragetime taken to consume itquantity and type of food present in
the stomachphysiology of the consumer
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BACBlood Alcohol Content
Expressed as percent weight per volume of blood
Legal limits in all states is 0.08%Parameters influencing BAC:
Body weight Alcoholic content Number of beverages consumed Time between consumption
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BACBurn off rate of 0.015% per hour but can vary: Male
BAC male = 0.071 x (oz) x (% alcohol)body weight
FemaleBAC female = 0.085 x (oz) x (% alcohol)
body weight
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Henry’s Law
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.
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Henry’s Law
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.
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Field Tests
Preliminary tests—used to determine the degree of suspect’s physical impairment and whether or not another test is justified.
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Field TestsPsychophysical test—
3Basic 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.
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Field Tests 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.
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The BreathalyzerMore practical in the fieldCollects and measures alcohol
content of alveolar breathBreath 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
36Chapter 8
The Breathalyzer
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
37Chapter 8
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.
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Generalizations
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.
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Generalizations
Breathalyzers now use an infrared light absorption device with a digital read-out. Prints out a card for a permanent record.
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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.
41Chapter 8
More Information
Read more about Forensic Toxicology from Court TV’s Crime Library at:
http://www.crimelibrary.com/criminal_mind/forensics/toxicology/2.html
Chapter 7
Drugs
“Having sniffed the dead man’s lips, I detected a slightly sour
smell, and I came to the conclusion that he had poison
forced upon him.”
—Sherlock Holmes, in Sir Arthur Conan Doyle’s
A Study in Scarlet
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Drugs and Crime
A drug is a natural or synthetic substance designed to affect the subject psychologically or physiologically.
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Drugs and Crime
“Controlled substances” are drugs that are restricted by law
Controlled Substances Act is a law that was enacted in 1970; it lists illegal drugs, their category and their penalty for possession, sale or use.
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Controlled Substances Act
Schedule I – high potential for abuse; no currently acceptable medical use in the U.S.; a lack of accepted safety for use under medical supervision
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Controlled Substances Act
Schedule II – high potential for abuse; a currently accepted medical use with severe restrictions; abuse may lead to severe psychological or physical dependence
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Controlled Substances Act
Schedule III – lower potential for abuse than the drugs in I or II; a currently accepted medical use in treatment in the U.S.; abuse may lead to moderate physical dependence or high psychological dependence
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Controlled Substances Act
Schedule IV – low potential for abuse relative to drugs in III; a currently accepted medical use in treatment in the U.S.; abuse may lead to limited physical dependence or psychological dependence relative to drugs in III
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Controlled Substances Act
Schedule V – low potential for abuse relative to drugs in IV; currently accepted medical use in treatment in the U.S.; abuse may lead to limited physical dependence or psychological dependence relative to drugs in IV
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Examples of Controlled Substances and Their Schedule Placement
Schedule I—heroin (diacetylmorphine), LSD, marijuana, ecstasy (MDMA)
Schedule II—cocaine, morphine, amphetamines (including methamphetamines), PCP, Ritalin
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Examples of Controlled Substances and Their Schedule Placement
Schedule III—intermediate acting barbiturates, anabolic steroids, ketamine
Schedule IV—other stimulants and depressants including Valium, Xanan, Librium, phenobarbital, Darvon
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Examples of Controlled Substances and Their Schedule Placement
Schedule V—codeine found in low doses in cough medicines
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Identification of DrugsPDR—Physicians’ Desk
Reference
Field Tests—presumptive tests
Laboratory Tests—conclusive tests
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Human ComponentsUsed for Drug Analysis
Blood
Urine
Hair
Gastric Contents
Bile
Liver tissue
Brain tissue
Kidney tissue
Spleen tissue
Vitreous Humor of the Eye
62Chapter 8
Physicians’ Desk Reference
PDR—a physicians’ desk reference is used to identify manufactured pills, tablets and capsules. It is updated each year. This can sometimes be a quick and easy identifier of the legally made drugs that may be found at a scene. The reference book gives a picture of the drug, whether it is a prescription, over the counter, or a controlled substance; as well as more detailed information about the drug.
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PDR Key
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Drug Identification
Screening or presumptive tests Spot or color tests Microcrystalline test—
a reagent is added that produces a crystalline precipitate which is unique for a certain drug.
Chromatography
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Drug Identification
Confirmatory testsSpectrophotometry
Ultraviolet (UV) Visible Infrared (IR)
Mass spectrometry
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Presumptive Color Tests
Marquis—turns purple in the presence of most opium derivatives and orange-brown with amphetamines
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Presumptive Color Tests
Dillie-Koppanyi—turns violet-blue in the presence of barbiturates
Duquenois-Levine—turns a purple color in the presence of marijuana
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Presumptive Color Tests
Van Urk—turns a blue-purple in the presence of LSD
Scott test—color test for cocaine, blue
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Chromatography A technique for separating
mixtures into their components Includes two phases—a mobile
one that flows past a stationary one.
The mixture interacts with the stationary phase and separates.
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Types of Chromatography
Paper Thin Layer (TLC) Gas (GC) Pyrolysis Gas (PGC) Liquid (LC) High Pressure Liquid (HPLC) Column
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Paper Chromatography
Stationary phase—paper
Mobile phase—a liquid solvent
Capillary action moves the mobile phase through the stationary phase
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Thin Layer Chromatography
Stationary phase— a thin layer of coating (usually alumina or silica) on a sheet of plastic or glass
Mobile phase—a liquid solvent
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People of Historical Significance
Francis William Aston was a British physicist who won the 1922 Nobel Prize in Chemistry for his work in the invention of the mass spectrograph. He used a method of electromagnetic focusing to separate substances. This enabled him to identify no fewer than 212 of the 287 naturally occurring elemental isotopes.
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