Chapter 8 tOX NOTES by 1hAsMAwq


									Chapter 8 Notes Outline
Toxicology: Poisons and Alcohol
        Definition—the study of the adverse effects of chemicals or
Forensic Toxicology
Toxic substances may:
        Be a
        Contribute to
Historical Perspective
         Lucretia Borgia—
         Madame Giulia Toffana—
         Hieronyma Spara—
         Madame de Brinvilliers and Catherine Deshayes—
         AND many others through modern times.
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
Aspects of Toxicity
        The chemical or physical form of
        The mode of entry into
        Body weight and physiological conditions of the victim, including
        The time period of
        The presence of other chemicals in the body or
Lethal Dose
        LD —refers to the dose of a substance that kills half the test population, usually

        Expressed in milligrams of substance
Federal Regulatory Agencies
        Food and Drug Administration (              )
        Environmental Protection Agency (               )
        Consumer Product
        Department of Transportation (          )

            Occupational Safety and Health Administration (          )
Symptoms of Various Types of Poisoning
        Type of Poison                       Symptom/Evidence
        Caustic Poison (lye)                Characteristic burns around the
        Carbon Monoxide            Red or pink patches on the chest and thighs, unusually
        Sulfuric acid                       Black
        Hydrochloric acid          Greenish-brown
        Nitric acid                         Yellow
        Phosphorous                         Coffee brown
        Cyanide                    Burnt almond
        Arsenic, Mercury           Pronounced
        Methyl (wood) or           Nausea and
        Isopropyl (rubbing) alcohol         possibly
Critical Information on Poisons
           Common                                    Symptoms resulting from an
           Characteristic                            Symptoms resulting from
           Solubility                                Disease states mimicked by
           Taste                                     Notes relating to the
           Common                                    Specimens from
           Lethal                                    Analytical
           Mechanism                                 Known
           Possible methods of                       Notes pertinent to
           Time interval of onset                    List of cases in which
To Prove a Case
        Prove a crime                             Access to
        Motive                                    Death was caused by
        Intent                                    Death was
        Access to
Forensic Autopsy: Look for:
         Mees lines—single transverse
Order toxicological screens
         Postmortem concentrations should be done at
         No realistic calculation of dose can be made
Human Specimens for Analysis
        Blood                                                             Liver
        Urine                                                             Brain
        Vitreous Humor Bile                                               Kidney
        Gastric                                                           Hair/nails
Alcohol—Ethyl Alcohol (C2H5OH)
         Most abused drug
         About 40% of all traffic deaths
         Toxic—affecting the central nervous system, especially
         Colorless liquid, generally
         Acts as
         Alcohol appears in blood
         About 5% is excreted
Rate of Absorption Depends on:

amount of                                                      quantity and type of
the alcohol content of                                         physiology of
time taken to
Blood Alcohol Content (BAC)
Expressed as percent weight
Legal limits in all states
Parameters influencing BAC:
         Body weight,
         Burn off rate of 0.015% per hour but can vary:
         BAC male = 0.071 x (oz) x (% alcohol)
        BAC female = 0.085 x (oz) x (% alcohol)
Alcohol and Law
         Between 1939 and 1964 a person having a blood-alcohol level more than 0.15 percent w/v was to be considered
         lowered to 0.10 percent
         In 1972, impairment level was recommended to
         Starting in 2003, states adopted the
Alcohol and Law
         The National Highway Traffic Safety Administration recommended an “implied consent” law to prevent drivers
         Adopted by all states by 1973, this law states that the operation of a motor vehicle on a public highway
         automatically carries with it the stipulation that a driver will submit for a test for alcohol intoxication if requested
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
         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
Field Tests
         Preliminary tests—used to determine the degree of suspect’s physical impairment and whether or not another
         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
                   One-leg stand (OLS): maintain balance, comprehend and execute two or more
The Breathalyzer
         More practical in
         Collects and measures alcohol
         Breath sample mixes with 3 ml of 0.025 % K2Cr2O7 in
         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
         During absorption, the concentration of alcohol in arterial blood will be
         Breath tests reflect alcohol concentration in
         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

Breathalyzers now use an infrared light absorption device with a digital read-out. Prints out a card


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