Forensic Toxicology - Richmond County School System
Forensic Toxicology SFS3. Students will analyze the use of toxicologyin forensic investigations. a. Classify toxins and their effects on the body. b. Compare the effects of alcohol on blood alcohol levels with regard to gender, and according to the law. c. Evaluate forensic techniques used to isolate toxins in the body. ESSENTIAL QUESTIONS How can you distinguish among the
types of toxins and their effects on the body? How are different forensic techniques used to isolate and identify toxins in the body? What factors influence the effects of alcohol on the body and why? Forensic toxicology is
the use of detecting and identifying the presence of drugs and poisons in body fluids, tissues, and organs to aid medical or legal investigation. The primary concern for forensic toxicology is not the legal outcome of the toxicological investigation or the technology utilized, but rather the obtaining and interpreting of the
results. History Earliest recorded use of poison was Socrates execution in 339 BC via ingestion of hemlock In the Renaissance, poisoning became an art, occupation, even a hobby.
History Philippus Theophrastus Aureolus Bombastus von Hohenheim (aka Paracelsus [~1525]) observed that any substance could be a poison, depending on its
dose: "All things are poison and nothing is without poison; only the dose makes a thing not a poison." History Mathieu Orfila, chairman of the legal medicine department at La
Sorbonne in France, published a book in 1814. This was the first attempt to systematically study and classify poisons. History Orfila was the first to articulate
the fact that poisons must be absorbed, or enter the blood, to manifest their effects. History In the U.S., forensic toxicology did not develop until the early 20th century in New York Dr. Alexander Gettler (lead FT in
NYC medical examiner lab) is considered this countrys first forensic toxicologist. Poison vs. Toxin vs. Venom Poison substances that cause biological disturbance when absorbed in sufficient quantities Toxin produced biologically
Venom injected via bite or sting Cyanide is poisonous Botulinum is toxic Rattlesnakes are venomous Types of Poisons Microbicide used to reduce infectivity of microorganisms chlorine, peroxide, antibiotics
Herbicide used to kill unwanted plants 2,4-D, atrazine, glyphosate (Roundup) Pesticide used to kill unwanted animals DDT, pyrethrin, nicotine Types of Toxins Hemotoxin destroy red blood cells
pit vipers Necrotoxin cause cell & tissue death brown recluse spider, flesh-eating bacteria Neurotoxin affect the nervous system Black widow spider, scorpions
Types of Venoms Fang-released snakes, centipedes, spiders Sting-released bees/wasps/ants, scorpions Other methods Hairs (caterpillars)
Tentacles (jellyfish) Saliva (Gila monster) Fins (lionfish, stingrays) Toxicity Dosage is indeed important, but so are The form of the substance Insoluble vs. soluble
How it enters the body Inhalation vs. injection vs. ingestion Body weight/age/sex of victim Toxicity Time period of exposure Acute vs. chronic toxicity
Interactions with other chemicals in the body Synergistic vs. antagonistic Toxicity LD50 refers to amount of substance that would kill 50% of test population within 4 hrs.
Typically represented as (mg subst. / kg weight) LD50 information <1 mg/kg = taste to drop ~500 mg/kg = ounce ~50 mg/kg = teaspoon ~5000 mg/kg = pint Sugar - LD50=29700 Ethanol - LD50=7060
Salt - LD50=3000 Caffeine - LD50=192 Nicotine - LD50=48 Cyanide - LD50=6.4 Botulinum toxin - LD50=0.00005 Roles of the Toxicologist
Must identify one of thousands of drugs and poisons Must find nanogram to microgram quantities dissipated throughout the entire body Not always looking for exact chemicals, but metabolites of desired chemicals (ex. heroin morphine within seconds)
Toxicology Procedures Presumptive/Screening quick test to narrow down possibilities spot/color tests Confirmation determines exact identity thin-layer/gas chromatography, IR
spectroscopy, mass spectrometry Presumptive/Screening Marquis Test: Turns purple in the presence of opiates Turns orange-brown in presence of amphetamines Scott Test:
Turns blue in the presence of cocaine Duquenois-Levine: Turns purple in the presence of tetrahydrocannabinal Marquis Test Scott Test
Duquenois-Levine Confirmatory Tests Microcrystalline Tests: Identifies drug by using chemicals that react to produce characteristic crystals Chromatography: Separates drugs and gives tentative ID Mass Spectrometry: Chemical
fingerprint no two drugs fragment the same IR Spectroscopy: IR light is absorbed by different chemicals Microcrystalline Tests Chromatography
Mass Spectrometry IR Spectroscopy Testing Samples Divided into 2 samples 1st sample is for screening test 2nd sample is for confirmatory test Only done for samples that test
positive during screening Testing Samples Blood 10 mL whole blood, anticoagulant, preservative More expensive, but more accurate, can detect hours to days usage
Urine Samples always given under direct supervision Easy, cheap, can detect hours to days usage Testing Samples Hair samples Collected from scalp or body
Can detect days to months usage Saliva Can detect hours to ~2 days usage Vitreous humor Only used post-mortem Resists putrefaction, can detect usage after embalming
Governmental Regulatory Agencies Food and Drug Administration Environmental Protection Agency Consumer Product Safety Commission Department of Transportation Occupational Safety and Health
Administration Controlled Substances Act In 1970, federal law established 5 schedules of classification of controlled substances based on Drugs potential for abuse Potential to physical and psychological dependence
Medical value Federal law also controls materials that are used in making drugs and those that are manufactured to resemble drugs DEA and FDA set classifications Controlled Substances Act
Abuse Inappropriate (misuse) or unwarranted use of substances, either legal (alcohol, prescriptions) or illegal Controlled Substances Act Dependence Physical dependence occurs
when the drug becomes necessary for the body to function normally. Withdrawal symptoms can lead to abuse NOT the same as addiction Psychological dependence occurs when a person thinks they
need a drug to function normally. Drug Schedules Schedule I: Drugs with high potential for abuse and addiction, NO medical value Ex: heroin, LSD, MDMA (Ecstasy), marijuana, GHB, peyote, psilocybin
Schedule II: Drugs with high potential for abuse and addiction, have some medical value with restrictions (no refills) Ex: PCP, cocaine, Ritalin, oxycodone, morphine, methamphetamine Drug Schedules Schedule III:
Drugs with less potential for abuse and addiction, currently acceptable for medical use (no more than 6 refills) Ex: Vicodin, codeine, ketamine, anabolic steroids Schedule IV: Drugs with low potential for abuse and addiction, currently acceptable for medical
use (no more than 6 refills) Ex: Valium, Xanax, Rohypnol Drug Schedules Schedule V: Drugs with low potential abuse, lowest potential dependency, acceptable for medical use Ex: antitussive, antidiarrheal, analgesic
medicines Classes of Drugs Stimulant Enhances the function or activity of the brain; causes alertness and motivation Depressant Relieves anxiety and muscle spasms; causes sedation and confusion
Hallucinogen Causes subjective changes in perception, thought, emotion and consciousness Narcotics (opioids) Slowed physical activity, analgesia, drowsiness Toxicology of Alcohol Alcohol is absorbed through the
stomach and intestine Once absorbed, alcohol is: Oxidized in liver by alcohol dehydrogenaseturned into acetic acid (vinegar) Excreted by breath, perspiration, and kidneysturned into carbon dioxide and water
Blood Alcohol Content Relates amount of alcohol per volume of blood Legal intoxication limit in US is 0.08, meaning 0.08 grams of ethanol per 100 mL of blood (4.5-5.5 mL absorbed [~1 tsp]) >0.20 Stupor >0.40 Unconsciousness/death
Alcohol and the Law 1939-1964: intoxicated = 0.15% BAC 1965: intoxicated = 0.10% BAC 2003: intoxicated
= 0.08% BAC At least we dont live in France, Germany, Ireland, or Japan (0.05%), Sweden or China (0.02%), and Russia or Saudi Arabia (0.00%) Factors that Affect Alcohol Absorption
Amount consumed More alcohol = more absorbed Alcohol content Maximum absorption with 20-25% alcohol Time of consumption Maximum absorption with 30 minute consumption period
Factors that Affect Alcohol Absorption Presence of food in stomach Food in stomach slows absorption of alcohol Body weight More weight = more water in body to dilute
alcohol Gender Females have more fat tissue = less water Time of Consumption & Food in Stomach on BAC Body Weight and Time of
Consumption on BAC Men vs. Women Blood Alcohol Content Measuring the quantity of alcohol in the blood system (BAC) determines the degree to which someone is intoxicated
Two methods of making this measurement Measurement of alcohol content in blood Measurement of alcohol in breath BAC Testing Blood alcohol is metabolized at the rate of 0.015 per hr, so
If your BAC is 0.08, how long will it take for your BAC to be 0.00? 0.08 0.015 = 5.33 hrs Alcohol is identical to the BAC tester 1 can of beer = 1 glass of wine = 1 shot of liquor Breath Tests Evidence has shown that the ratio of
alcohol in the blood to alcohol in alveoli air is approx. 2100 to 1This is a basis for relating breath to blood-alcohol concentration. One instrument used for breath tests is called The Breathalyzer. The Breathalyzer
The Breathalyzer Cont The Breathalyzer traps 1/40 of 2100 milliliters of alveolar breath, so it, in essence, measures the alcohol concentration present in 1/40 of a milliliter of blood. Developed in 1954, it was originally based on a color change observed by spectroscopy
Other Breath Tests Infrared spectrophotometer technology Electrochemical fuel cell technology These instruments are used more recently because they dont depend upon chemical reagents and are entirely automated.
Infrared and Fuel Cell Breath Tests Infrared Breath Test uses infrared wavelengths to test for alcohol or other interferences in the breath
Fuel Cell Test converts fuel (alcohol) and oxygen into a measurable electric current Field Sobriety Testing Two reasons for the field sobriety test:
1. Used as a preliminary test to ascertain the degree of the suspects physical impairment 2. To see whether or not an evidential test is justified Field Sobriety Testing Methods Field sobriety testing consists of a series of psychophysical tests and a
preliminary breath test (typically done with a handheld fuel cell tester) These tests are preliminary and nonevidential in naturethey only serve to establish probable cause requiring a more thorough breath or blood test Field Sobriety Tests
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