Forensic Toxicology

Toxicologist  An individual charged with the responsibility of detecting and identifying the presence of drugs and poisons in body fluids, tissues, and organs

Not only for death investigations  Hospitals labs for drug overdoses  Blood tests on children for exposure to lead  Examine urine of addicts

Toxins  Any material exerting life threatening effects upon a living organism  A toxin is a poisonous substance produced by a living organism  Poisons are a subcategory of toxins

Toxins vs Poisons  May enter the body in different ways.  Work in low quantities or low levels  Easy to detect  If treatment is early, the person can be saved.  Normally enter in a single massive dose  Normally are found in huge doses.  Hard to detect  People often die because the reason for illness is not detected soon enough.

Dose-Response Relationship  Relationship between the amount of a substance that a human would be exposed to and the relationship to their body after exposure.

Lethal Dose  Lethal dose is the dose taken that would cause death to the organism  To determine the Lethal Dose scientists test two different animals and two different methods of exposure (one being the way humans would take the substance)

Lethal Dose  In a lethal dose study, scientists will study how much will have to be given to the two different animals in order to cause death.  Animals in these studies normally die within 14 days and scientists can take their results from these tests and relate them to human beings.

Most heavily abused substance is legal!!  Ethyl Alcohol  40% traffic deaths  17,500 fatalities a year  2 million injuries a year

Toxicology of Alcohol  Metabolism- the transformation of a chemical in the body to other chemicals for facilitating its elimination from the body  3 steps  Absorption  Distribution  Elimination

Absorption  Alcohol appears in the blood minutes after consumption and increases in concentration while it is being absorbed from the stomach and small intestine into the bloodstream.  Absorption= the passage of a substance across the wall of the stomach and small intestine into the blood stream

What affects rate of absorption  How long it takes to consume a beverage  Alcohol content of beverage (proof)  The amount consumed  Food present in stomach

Distribution of Alcohol  Bloodstream  BAC tests performed

Elimination  Oxidation % of the alcohol undergoes this chemical process which converts alcohol to carbon dioxide and water. Occurs in liver.  Elimination- 2-5% is excreted by perspiration, urination, and breathing

Breathalyzer Test  The amount of alcohol exhaled in the breath is in direct proportion to the concentration of alcohol in the blood.

Elimination varies with individual  Weight  Muscle tone or physical condition  History with drug (tolerance)  Metabolism  Age

Blood Alcohol concentration

Blood Alcohol Content  Most accurate test  Requires blood

Absorption  20% absorbed by the stomach  80% by small intestines  All alcohol is broken down by liver  Arteries will have a higher BAC than veins during absorption  Blood tests retrieve blood from veins

Testing for intoxication  BAC not convenient for traffic officers  Breath testing performed  Breathalyzer  Developed 1954 by R.F. Borkenstein  Uses chemicals to detect BAC

Fuel Cell detector  A chemical reaction involving alcohol produces electricity  Will give officer a digital readout of BAC

Errors in detection  Police are supposed to ensure no foreign material is in mouth for 15 minutes before test  Regurgitation (throwing up)  Belching  Recent Drinking  Gargling with an alcohol based mouthwash

Field sobriety tests  Deal with physical impairments  Stand on one leg  Walk straight line  Horizontal gaze nystagmus  Walk heel to toe

Alcohol and the law  1992 US Department of Transportation (DOT) required states adopt 0.08% BAC  Made federal law in 2000  If an individual exceeds.08% they are deemed “intoxicated”  In 2003 states that did not abide with this law lost federal funding for highway construction

Alcohol and the law  Commercial drivers such as bus or 18 wheelers must not exceed.04 % BAC

Is it constitutional??  5 th amendment states that you have the right to not incriminate yourself  Driving is a privilege not a “right” so they may take away your license for refusing to test (6 months-12 months)

Role of the Toxicologist  Generally there are few signs that indicate what type of poison in system  Clues arise from  Medicine bottles  Household chemicals  Postmortem pathological examination

Toxicologist must  Work with nanograms and micrograms of specimen due to absorption of body  Pure samples are easier to analyze  The body metabolizes each substance differently  Example- heroin is almost immediately broken down to morphine in the body  Toxicity levels vary by individual

Toxicologist handles  Blood (a minimum of 10 ml required)  Urine

90% of the drugs encountered in a toxicology lab are:  Cocaine  Alcohol  Marijuana

Acid/Base Tests  Toxicologist can extract acidic drugs from acidified water using chloroform  Basic drugs can be extracted using basic water solutions and organic solvents

Drugs  Acidic  Barbituates  Aspirin  Basic  Phencyclidine  Methadone  Amphetamines  Cocaine

Famous cases  1982 Tylenol was tampered with in Chicago. Someone opened up the gels capsules and replaced drug with potassium cyannide  7 deaths  $100,000 reward from tylenol for information

Toxicology of hair  Most drugs leave bloodstream within 24 hours. Urine tests are accurate up to 72 hours on average  Drugs present in blood diffuse through capillary walls into the base of hair and become permanently entrapped in the protein structure

Toxicology of hair  As the hair grows, the drugs location on the hair shaft becomes a historical marker for drug intake  Human hair grows an average of 1 cm a month

Nondrug poisons  Heavy metals- Substance is placed in HCl with a copper strip. Silver or dark coating means presence of heavy metal. Confirmation tests necessary.  Arsenic  Bismuth  Lead  Antimony  Mercury  Thallium

Nondrug poisons  Carbon Monoxide (CO)  Suicide by car- usually a vacuum hose or garden hose in tailpipe to stream gas into car minutes in single car garage with car running is sufficient for death  Also seen in fires.

Drug Recognition Experts  3-5 month Training  Can suggest if victim/offender exhibited behaviors associated with:  CNS depressants  CNS stimulants  Hallucinogens  Dissociative Anesthetics (phencyclidine)  Inhalants  Narcotic Analgesics  Cannabis