Chapter 8 Toxicology: Poisons and Alcohol “All substances are poisons. There is none which is not. The right dose differentiates a poison and remedy.”

Chapter 8Toxicology:

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

Chapter 8 Kendall/Hunt Publishing Company 2

Toxicology and Alcohol

A quantitative approach to toxicology.

The danger of using alcohol.

Students will learn:


Toxicology and Alcohol

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.

Students will be able to:


Toxicology

Definition—the study of the adverse effects of chemicals or physical agents on living organisms.

Types:Environmental—air, water, soilConsumer—foods, cosmetics, drugsMedical, clinical, forensic


Forensic Toxicology

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:Be a cause of deathContribute to deathCause impairmentExplain behavior


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.


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”


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.


Aspects of Toxicity

Dosage The chemical or physical form of the substance The mode of entry into the body Body weight and physiological conditions of the

victim, including age and sex The time period of exposure The presence of other chemicals in the body or

in the dose


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


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


Federal Regulatory Agencies

Food and Drug Administration (FDA)Environmental Protection Agency (EPA)Consumer Product Safety CommissionDepartment of Transportation (DOT)Occupational Safety and Health

Administration (OSHA)


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 Phosphorous Coffee brown vomit. Onion or garlic odor Cyanide Burnt almond odor Arsenic, Mercury Pronounced diarrhea Methyl (wood) or Nausea and vomiting, unconsciousness,

Isopropyl (rubbing) alcohol possibly blindness


Critical Informationon Poisons

Form Common color Characteristic odor Solubility Taste Common sources Lethal dose Mechanism Possible methods of administration Time interval of onset of

symptoms.

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”


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


Forensic AutopsyLook 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



Human Specimens for Analysis

Blood Urine Vitreous Humor of

Eyes Bile Gastric contents

Liver tissue Brain tissue Kidney tissue Hair/nails


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% in the liver About 5% is excreted unchanged in breath, perspiration

and urine


Rate of Absorption

Depends on:amount of alcohol consumed the alcohol content of the beverage time taken to consume itquantity and type of food present in the

stomachphysiology of the consumer


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


BAC

Burn off rate of 0.015% per hour but can vary:

MaleBAC male = 0.071 x (oz) x (% alcohol)

body weight Female

BAC female = 0.085 x (oz) x (% alcohol) body weight


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.

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.


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.


The Breathalyzer 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 water2K2Cr2O7 + 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


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.


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.


More Information

Read more about Forensic Toxicology from Court TV’s Crime Library at:

http://www.crimelibrary.com/criminal_mind/forensics/toxicology/2.html



Documents

Chapter 8 Toxicology: Poisons and Alcohol “All substances are poisons. There is none which is not. The right dose differentiates a poison and remedy.”