Chapter 8 Toxicology: Poisons and Alcohol

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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MechanismPossible methods of administrationTime interval of onset of symptoms.Symptoms resulting from an acute

exposureSymptoms resulting from chronic

exposure


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Disease states mimicked by poisoning

Notes relating to the victimSpecimens from victimAnalytical detection methods


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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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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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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

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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

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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.

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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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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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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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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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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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Schedule III—intermediate acting barbiturates, anabolic steroids, ketamine

Schedule IV—other stimulants and depressants including Valium, Xanan, Librium, phenobarbital, Darvon

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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

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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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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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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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Chapter 8 Toxicology: Poisons and Alcohol

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