Transcript 10.4 – The Role of the Toxicologists

The Role of the Toxicologists
Objectives

Appreciate the significance of
finding a drug in human tissues
and organs to assessing
impairment
Challenges

 Presented with body fluids and/or organs and asked to
examine for drugs or poisons
 Sometimes they possess clues to type of toxic substance
 Victim’s Symptoms
 Postmortem pathological examination
 Examination of victim’s physical effects
 Presence of containers
 Household cleaners
 Without those clues, rely on general screening procedures
Challenges continue…

Dealing with drugs that have been
dissipated and distributed throughout the
body
 Not at concentrated level found in pills and powders
 Forced to work with nano or microgram amounts
Factor in metabolic activity of body
Must be prepared to assess toxicity levels
Capabilities of
toxicologist

Dependent on input from
Attending physician
Medical Examiner
If victim is dead, M.E. decides what to send
to toxicologist
If living = blood and urine send to
toxicologist
Police Investigator
Collection &
Preservation

Upsurge in drug use and abuse
means overwhelming majority of
fatal and nonfatal toxic agents are
drugs
90% accounted for by alcohol,
marijuana, and cocaine
Acids & Bases

Acid Drugs
Basic Drugs
Barbiturates
Methadone
Aspirin
(acetylsalicylic acid)
Amphetamines
Cocaine
 Acid = donates hydrogen ion (H+)
 0-7 on pH scale
 Base = accepts H+
 7-14 on pH scale
 Neutral = water = 7 on pH scale
Extraction of Acids &
Bases

Add acidic or basic substances to
water to change pH value
Control pH value of water
solution into which blood, urine or
tissues are dissolved
Extraction of Acids &
Bases

Toxicologist can control the type of
drug that is recovered
Drugs extracted from altered water
by adding organic solvents
Acid drugs easily extracted from
acidified water solution
10.6 Questions
1. Describe the two challenges toxicologists face in
detecting drugs and determining their toxicity.
2. What three drugs account for 90% or more of the
drugs encountered in a typical toxicology
laboratory?
3. What bodily fluids should be collected from any
suspected drug user?
4. What are acids and bases? How are they used to
extract and categorize drugs?
5. What is the first task of a forensic toxicologist
when establishing an analytical scheme to detect
and identify drugs?