Forensic Toxicology “All substances are poisons. There is none which is not. The right dose differentiates a poison and a remedy” -Paracelsus ( ) Swiss physician and chemist Ch 5 pages 61-77

I. Introduction  Forensic toxicology is the study of poisons as they pertain to legal matters.

II. Applications of Forensic Toxicology  3 main areas:  Postmortem Drug testing  Workplace drug testing  Investigation of contraband materials

A. Postmortem Drug Testing  Postmortem Drug testing consists of a death investigation with a goal of establishing whether drugs were the cause or a contributing factor.  Accidental or deliberate overdose

B. Workplace Drug Testing  Workplace Drug Testing consist of the evaluation of biofluids, (urine, blood) from employees or applicants, for drug content.

C. Investigation of Contraband materials  Evaluation of Contraband materials is used to identify prohibited drugs.  Labs prove that seized material is illegal or not.

IV. Testing Process Specimen Collection 1. Blood:  Is the most important specimen  2 sample are taken; from heart and then peripheral site  Concentration of toxins in blood is more accurate than any other fluid 2. Urine:  Is beneficial… b/c large amounts can be collected  Drug concentration level is usually low

3. Gastric Contents:  Is beneficial in the case of a deceased who has ingested large amounts of lethal agents  Usually in the case of suicide 4. Hair:  Not common in Forensic toxicology investigations because drugs in the hair are extremely low  Can show passive exposure  Can show a long term exposure to drugs

5. Vitreous Humor:  Fluids from the eye  Is resistant to breakdown, and takes a long time to decay  Can also be used to estimate time of death 6. Bile and Liver:  May contain significant quantities of most drugs because the liver is used in metabolism of drugs

Drugs of Abuse  Drugs cited in the National Laboratory Certification Program  Amphetamines  Opiates  Phencyclidine  Cocaine  Cannabinoids

Amphetamines  Amphetamines and methamphetamines  Stimulants that create an excitable condition characterized by an elevation in heart rate, blood pressure, and respiratory rate.  Cause intense euphoria  Include: ephedrine, phenylpropanolamine, phenylephrine,

Opiates  Opiates  Constitute a large class of drugs distinguished by their ability to cause profound euphoria.  High potency pain relievers  Classified as depressants, reduced muscle activity, depressed respiration, heartbeat, inclination to sleep  Grow in large amounts in Asia  Include; morphine, codeine, heroin, OxyCotin, hydrocodone, oxycdone,

Phencyclidine  Phencyclidine  Aka. PCP, or peace pill  Originally intended for use as a surgical anesthetic  Users show euphoria, feelings of detachment, strength, power, severe perceptual distortions, violent behavior, psychosis, paranoia, and hallucinations

Cocaine  Cocaine  Is a stimulant that resembles amphetamine in its abusive potential  Is a natural product that include “free base”, “crack”

Cannabinoids  Cannabinoids  The related psychoactive compounds that come from the plant Cannabis Sativa.  Aka. Marijuana  Tetrahydrocannabibol (THC) is the active agent  Drug state includes: mood swings, euphoria, perceptive alterations, memory impairment, low motivation

Analytical Methods in Forensic Toxicology 1. The approach to testing for substances has 2 parts:  screening  confirmation

Screening Tests Immunoassays  – are tests in which antibodies are used.  -they enable the regents to react only with a substance that recognizes the antibody.

Screening Tests 2. Thin Layer Chromatography  (TLC) the specimen is extracted into an organic solvent and spotted onto a glass plate coated with silica  the plate is placed into a tank that separates whatever chemicals were originally present in the specimen.  Toxins are identified by the distance they migrate up the plate

Screening Tests 3. UV Visible Spectrophotometry  most drugs absorb light  each drug produces a characteristic spectrum that allows the drug to be identified because it has peak absorbance at a certain wavelength

Confirmation analysis Gas Chromatography  is a method in which substances are separated from other components of a mixture on a column Gas Chromatography – Mass Spectrometry  is a combined method in which substances are separated from other components of a mixture on a column and a mass spectrum is also obtained  Bombarded with electrons

Interpreting Drug Findings The goal of a forensic toxicologist in a postmortem investigation is to collaborate with the forensic pathologist in determining the cause and manner of death

Non medicinal Agents  Many deaths are due to chemicals that are not medicinal and/or are encountered in the environment.  Alcohol  Cyanide  Carbon Monoxide  Hydrocarbons  Heavy Metals

Alcohols  Ethanol is beverage alcohol  Enter the membranes of the nerve cells and disrupt their normal architecture  Contributes to numerous disorders as a result of a chronic abuser (Liver and brain)  Is usually measured by gas chromatography

Cyanide  Highly toxic substance found in many forms  gas; hydrogen cyanide  solid: sodium cyanide  death occurs quickly  antidotes can save those exposed to only small amounts

Carbon monoxide  CO, prevents the transport of oxygen  Causes more deaths that any other toxic substance  Present in fires, car exhaust

Hydrocarbons  Are commonly found in nature…..  Death is due to high exposure, or accident following erratic behavior brought on by the effects of hydrocarbons on the brain  Hydrocarbons can be gases (methane and propane), liquids (hexane and benzene), waxes or low melting solids (paraffin wax and naphthalene) or polymers (polyethylene, polypropylene and polystyrene).

Heavy Metals  individual metals and metal compounds that negatively affect people's health.  in larger amounts, they become toxic. They may build up in biological systems and become a significant health hazard.  Arsenic  Beryllium  Lead  Mercury  Cadmium