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2009©Forensic Science Today Forensic Toxicology Saferstein, Criminalistics, Chapter 10.

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Presentation on theme: "2009©Forensic Science Today Forensic Toxicology Saferstein, Criminalistics, Chapter 10."— Presentation transcript:

1 2009©Forensic Science Today Forensic Toxicology Saferstein, Criminalistics, Chapter 10

2 2009©Forensic Science Today Goal of Toxicologist ► Examine tissue or fluids from humans and other animals to answer the questions:  Are drugs present?  Are poisons present?  Are there unknown chemicals present?

3 2009©Forensic Science Today Also Must Determine ► The effects the drug, poison or unknown chemical has on the human or other animal. ► “All things are poison and nothing is without poison, only the dose permits something not to be poisonous.” - Paracelsus, 16 th Century - Paracelsus, 16 th Century

4 2009©Forensic Science Today Alcohol ► Most heavily abused drug in Western countries  accounts for 40% of all traffic deaths in the U.S. ( 17,500 per year) ( 17,500 per year) ► How much consumed?  type of drink ► Distilled or fermented  Distilled is 40-100% ethyl alcohol  Fermented is 3-15% ethyl alcohol - Beer 4 -6 % - Beer 4 -6 % - Wine 12-15% - Wine 12-15% Proof ÷ 2 = % alcohol

5 2009©Forensic Science Today Absorption of Alcohol ► Ingestion, injection and inhalation - not digested (absorbed directly into bloodstream) - not digested (absorbed directly into bloodstream) ► Rate slowed by food in the stomach - alcohol in a single beverage absorbed in 45 min to 1 hour on an - alcohol in a single beverage absorbed in 45 min to 1 hour on an empty stomach empty stomach ► Type of beverage- % alcohol, amount and rate of consumption ► Altitude- at higher altitude, absorption is faster. ► Body weight- alcohol dissolves in “watery portions of the body”

6 2009©Forensic Science Today Toxicology- Not Just Involved in Deaths ► Athletes ► Employees ► Driving accidents ► Sexual assaults ► Animals in racing industries ► Industrial accidents

7 2009©Forensic Science Today Blood-Alcohol Concentration ► After ingestion, alcohol is absorbed from the stomach and small intestines into the bloodstream. ► Blood circulates the alcohol through the body, carrying it to the tissues and into the brain. ► The blood-alcohol concentration is proportional to the amount of alcohol in the brain.

8 2009©Forensic Science Today Ethanol in the Body ► Most substances that enter the stomach are digested. Ethanol is an exception; it is directly absorbed resulting in rapid intoxication. Aspirin is also absorbed, resulting in quick relief of a headache. ► Alcohol is one of only a few substances capable of passing the blood-brain barrier, causing intoxication.

9 2009©Forensic Science Today Time of Absorption ► Alcohol appears in the blood within minutes after consumption. ► Under normal social drinking conditions, the absorption of alcohol takes from 30-90 minutes from the time of the final drink. (Max. blood-alcohol concentration) Times vary greatly and may take 2-3 hours.

10 2009©Forensic Science Today Elimination ► Once absorbed, alcohol is distributed throughout the body’s water; the body immediately begins to eliminate the presence of alcohol by oxidation and excretion. ► Oxidation occurs in the liver to break alcohol down into acetaldehyde and acetic acid and then into CO 2 and H 2 O. ► The remaining portion of alcohol is excreted unchanged in the breath, urine and perspiration.

11 2009©Forensic Science Today Chemical Formulas ► Ethanol Acetaldehyde ► can cause cancer and/or liver damage ►

12 2009©Forensic Science Today Measurement of BAC ► Direct chemical analysis of blood for alcohol content ► Measurement of alcohol content of breath

13 2009©Forensic Science Today Legal Limit for BAC ► U.S. Legal BAC Limit is 0.08 %. ► Drivers are impaired at 0.05%- US National Safety Council has pushed to lower the legal limit. (Thirty years ago, limit was 0.15%) ► Australia, South America, Taiwan, France, Denmark, Turkey 0.05% Limit ► China, Japan 0.03% Limit ► Sweden 0.02% Limit ► Russia, Saudia Arabia, Jordan 0.00% Limit ► Ref: Dr. Henry Lee et. al, Forensic Science Today, 2009, p. 204

14 2009©Forensic Science Today BAC Limit for Commercial Drivers ► Max. BAC limit in the U.S. for commercial truck and bus drivers is 0.04%.

15 2009©Forensic Science Today Alcohol-related Accidents ► A driver with a BAC level of 0.08% is 4 times more likely to be involved in an accident as compared to a sober driver.

16 Effects of Alcohol BAC % Effect 0.02Euphoria – more self-confident, poor judgment, flushed, shorter attention span 0.04Relaxation 0.06Impaired driving, poor judgment 0.08Impaired motor skills, poor coordination, legally intoxicated 0.12Vomiting begins for inexperienced drinkers 0.15Loss of balance (equivalent to 1/2 pint of liquor in the blood stream) 0. 4Loss of consciousness, death (LD 50 – dose that causes death in 50% of the population) 2009©Forensic Science Today

17 How Much Drinking Does It Take to Get Drunk? ► For a male: ► Volume = wgt x BAC ► 3.78 ► For a female: ► Volume = wgt x BAC ► 4.67 ► Drinking is done on an empty stomach. Drinks are 100 proof and ingested at once. ► Weight (wgt) is in pounds, volume is in ounces, BAC is g/dL. ► Source: Siegel, Jay & Kathy Mirakovits. Forensic Science, the Basics 2 nd Edition, 2010, p. 398. ► 2009©Forensic Science Today

18 Implied Consent Law ► Enacted in 1973 ► All drivers agree to submit to a test for alcohol intoxication if requested or be subject to loss of the license for some designated period- usually 6-12 months

19 2009©Forensic Science Today Field Sobriety Testing ► Provide Preliminary, nonevidential results ► Establish probable cause for more thorough testing ► Portable breath tester- fuel cell absorbs the alcohol from the breath samples, oxidizes it, and produces an electric current proportional to the breath-alcohol content. ► See Figure 10-7, p. 277 Saferstein, Criminalistics, 2004. ► Psychophysical tests include horizontal gaze nystagmus (involuntary jerking of the eyes as they move from side to side fig 10-8), walk and turn, and the one-leg stand

20 2009©Forensic Science Today Testing for Alcohol in Drivers ► Prior to 1950’s, blood sample was needed. ► Breathalyzer was invented in 1954 by Dr. Robert Borkenstein, an Indiana State Police Captain. ► Advantages: ► Ease in sampling ► Analyzers readily available to Law Enforcement ► Provides instant results ► Provides valuable evidence in court

21 Pharmacology The study of all the interactions of drugs and similar substances on living beings 2009©Forensic Science Today

22 Pharmacology ► Toxicology is a branch of pharmacology. ► Administration of drugs ► Absorption into the body ► Actions and interactions ► Metabolism and elimination 2009©Forensic Science Today

23 Drug Intake ► How does drug interact with organs? ► How quickly must the drug be absorbed? ► Route of ingestion affects the rate the drug enters the bloodstream. ► Oral administration is normally the slowest means of getting a drug into the bloodstream. 2009©Forensic Science Today

24 Absorption ► Drug vapors enter the bloodstream through alveoli in the lungs. ► Oral dosages are absorbed into the bloodstream through the stomach or small intestine or both. ► Drug user can control the dosage for oral ingestion, but not the rate of absorption. 2009©Forensic Science Today

25 Drugs exert their most important effects on the BRAIN. 2009©Forensic Science Today

26 Drug Effects ► Pesticides build up in fatty tissues over time. ► Heavy metals like Hg or Pb, collect in the teeth, gums, fingernails, toenails and hair. ► LSD collects in the brain. Abusers often suffer flashbacks years after LSD use. 2009©Forensic Science Today

27 Elimination

28 Half - Life ► time required for the concentration of a drug in the bloodstream to reduce to half to reduce to half of the initial concentration 2009©Forensic Science Today

29 Metabolism ► Liver- The Body’s Chemical Factory ► Changes the drug into a different substance called a metabolite. 2009©Forensic Science Today

30 Image of a Liver damaged by Cirrhosis 2009©Forensic Science Today An irreversible liver disease caused by excessive alcohol consumption

31 Metabolism ► Changes the drug into a less harmful or toxic substance. ► Changes the drug into a form that makes it easier to eliminate in the urine by making it more soluble. 2009©Forensic Science Today

32 Elimination of Drugs from the Body ► Volatile drugs can by exhaled in the breath. ► Water-soluble drugs can be eliminated in perspiration. ► Majority of drugs are eliminated in the urine, either as the drug or a metabolite. 2009©Forensic Science Today

33 Delayed Elimination ► Some drugs such as marijuana remain in the body for months after ingestion and, with regular use, will increase in concentration. 2009©Forensic Science Today

34 Multiple Drug Use ► When drugs are used in combination, the results may be synergistic. That is, the effects of the combination are worse than two doses of a single drug. ► Alcohol and barbiturates caused the death of Marilyn Monroe the death of Marilyn Monroe coming/joanne coming/joanne

35 2009©Forensic Science Today Toxicology on the Job ► On-the-job drug testing is becoming more common. ► Traditional urine testing ► Tests under development for testing hair, saliva or sweat

36 2009©Forensic Science Today The Role of a Toxicologist ►E►E►E►Examines bodily fluids and/or organs for the presence of drugs or poisons ►C►C►C►Careful extraction may yield only microgram or nanogram concentrations ►B►B►B►Body is an “active chemistry laboratory”. A thorough understanding of how the body alters or metabolizes the chemical structure of a drug is essential. ►A►A►A►Assesses the toxicity of a substance

37 Chromatography ► Used to identify many types of substances especially in mixtures. ► Used to determine alcohol content in blood (see fig 10-9, p. 279) ► Works by using a substance’s  Solubility  Attraction to a surface and  Mass

38 2009©Forensic Science Today Equipment & Techniques Used ► Gas & liquid chromatography- allows for separation of a mixture of compounds ► Mass Spectrometry- used to identify the chemical structure of an unknown by fracturing a pure compound into smaller pieces (combined with GC) ► UV-Vis- shows how substances absorb light (classifies compounds) ► AA & Flame- Analysis for the presence of metals ► Immunoassay- quantization of a compound ► Standard chemistry techniques

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