FOR10002 Lecture Notes - Lecture 3: Forensic Toxicology, Toxicology, Chronic Toxicity
FOR10002 FORENSIC SCIENCE
WEEK 3 — Toxicology
Toxicology is the science of poisons and deals specifically with the detection of drugs and
poisons in biological systems.!
A forensic toxicologist applies analytical toxicology to the needs of the law.!
Any chemical can be a toxin, the amount is what’s important and whether it goes above the
threshold period in the body.!
A forensic pharmacologist assists the toxicologist in interpreting what the presence of any
chemical substance means in relation to effects on a living system.!
Hazardous substances can harm you physically.!
Toxic substances will usually affect you biochemically. !
(all toxic substances are hazardous but not all hazardous substances are toxic).!
eg. Snakes are hazardous but the venom is toxic.!
Routes for toxins:!
•Inhalation!
•Ingestion (anything you eat enters the bloodstream through absorption) !
-absorption — something is taken up through the surface !
-adsorption — substance stays on the surface!
•Injection!
•Contamination of food (topical?)!
Acute toxicity: see effects for short time (short term effect)!
Chronic toxicity: long-term effects!
Analytical Forensic Toxicology!
Use of analytical techniques for analysis of drugs and other chemicals in forensic samples:!
•Biological specimens - blood, urine, oral fluid, etc!
•Physical exhibits - syringes, tablets, powders, etc!
Then these tests result in a report.!
DIFFERENT LABS - DIFFERENT TESTS
•Hospital/pathology labs - therapeutic monitoring of drugs (DTM)!
•Sports labs - only sports of drugs mainly in urine!
•Racing labs - horse/dog/jockey urine!
•Forensic labs can do most tests and cover the widest range of drugs.!
DRUGS OF MOST CONCERN
•Alcohol!
•Cannabis!
•Prescription drugs - benzodiazepines, antidepressants, etc!
•Stimulans - methamphetamine, cocaine!
•Heroin like drugs (including legal opiates)!
•GHB/Volatile substances!
find more resources at oneclass.com
find more resources at oneclass.com
Synthetic Drugs!
•No additional compounds present that match common mass or UV spectra libraries - hard to
identify!
•No cross-reactivity to commonly used drug test assays on antibodies - limited tests!
•Over 600 compounds!
•Difficult to detect, no one method can cover all compounds !
•Little is known about pharmacology!
•No safe level!
•Often sold as mixtures!
•Can cause seizures, psychosis, delusions, stroke, tachycardia, and death!
Toxicology Labs!
•The presence of a drug is reported at a detectable level!
•Not limited to blood or urine!
-Oral fluid, hair in clinical cases!
•Liver, stomach contents, vitreous humour (deceased only)!
•Interpretation of drug concentration is essential and needs context!
Roles of Forensic Toxicology!
TO ASSIST IN RECONSTRUCTING THE EVENTS LEADING UP TO THE CASE
•To establish or refute use of drugs - @5500 cases p.a. !
ASSISTS IN THE DETERMINATION OF THE CAUSE AND MANNER OF DEATH
•Homicides/suicides/drug related cases !
•Industrial accidents/drivers of motor vehicles !
•Medical deaths including adverse reactions !
•Unknown and other cases as required !
ESTABLISH IF DRUG-INDUCED BEHAVIOURAL CHANGES OCCURRED
•Drugs in driving cases !
•Sexual assaults cases!
Other Applications!
CORRECTIONAL FACILITIES
•Urine testing for drugs of abuse !
EMPLOYMENT TESTING
•Targeted testing on persons suspected of drug use !
•Random to enforce “zero- tolerance” !
•Ensure “new” employees are not a higher risk to company !
SPORTS TESTING
•Test for banned substances in athletes !
RACING INDUSTRY
•Horses (thoroughbreds, trotters, greyhounds etc) !
CLINICAL TOXICOLOGY
find more resources at oneclass.com
find more resources at oneclass.com
Drugs in Serious Assaults!
DRUGS ARE FOUND IN OVER HALF OF ALL OFFENDERS IN ASSAULT CASES
•And a similar percentage in victims of homicide !
DRUGS OF MOST INTEREST ARE:
•Alcohol !
•Benzodiazepines !
•Amphetamines !
•Heroin !
DRUG USE HAS IN MOST OF CASES A SIGNIFICANT EFFECT ON BEHAVIOUR
•Driving motor vehicles!
Postmortem Toxicology!
•Coronial cases - deceased !
•Complex toxicology !
•Looking for the unknown! !
•Systematic toxicological analysis (STA) !
•Specialist analysis ie volatiles, GHB !
•“Other” specimens – ie hair, muscle!
Use of Drugs in the Community!
•Over 80% admit to drinking alcohol regularly !
•5-10% have a drinking problem !
•Over 20% of the population admit to using illicit drugs at some stage of their life !
•Some 5% are probably using regularly !
•About 4% of the population admit to misuse of pharmaceutical drugs !
•We see about 300-400 drug deaths per year, but the majority of 4000+ unnatural deaths/
criminal cases are positive !
Prescription Drug Use & Abuse!
Prescription drugs are over-used by many Australians leading to misuse, and all the way to abuse !
•Opioids (morphine, methadone, oxycodone, fentanyl) !
•Benzodiazepines (alprazolam, diazepam etc) including zolpidem (Stilnox) !
•Possibly even anti-depressants !
Using too much or for too long leading to tolerance and dependence !
Often in combination with alcohol and other drugs!
Failing of Drug Tests!
WHICH DRUGS CAN FAIL THE DRUG TEST?
•Using fentanyl !
•Regular urine specimen testing !
•Never tested positive to opioids !
•Laboratory not informed of fentanyl use !
Drug Testing!
•Requires unequivocal determination of a drug presence !
•Initial test conducted to see if any substance might be present !
•A confirmation test is conducted after “initial test” !
•Must use a mass spectroscopic method !
-GC-MS or LC-MS !
-Mainly tandem MS, ie MS/MS!
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Toxicology is the science of poisons and deals speci cally with the detection of drugs and poisons in biological systems. A forensic toxicologist applies analytical toxicology to the needs of the law. Any chemical can be a toxin, the amount is what"s important and whether it goes above the threshold period in the body. A forensic pharmacologist assists the toxicologist in interpreting what the presence of any chemical substance means in relation to e ects on a living system. Toxic substances will usually a ect you biochemically. (all toxic substances are hazardous but not all hazardous substances are toxic). eg. snakes are hazardous but the venom is toxic. Routes for toxins: inhalation, ingestion (anything you eat enters the bloodstream through absorption) Absorption something is taken up through the surface. Adsorption substance stays on the surface: injection, contamination of food (topical?) Acute toxicity: see e ects for short time (short term e ect)
