Forensic Overview Flashcards
What is toxicology?
the analysis of body fluids and tissue for the presence of drugs and poisons
ex. urine, blood, kidney or liver tissue
What does toxicology involve?
- identification
- quantitation
- interpretation
What are the different levels of drug concentrations?
- therapeutic
- toxic
- lethal
What are 2 subspecialties of toxicology?
- clinical toxicology
- forensic toxicology (dealing with crimes man)
List the 3 areas of forensic toxicology
1) Postmortem forensic toxicology
2) Human performance forensic toxicology
3) Forensic drug testing
Describe postmortem forensic toxicology
- cause and manner of death
- analysis of body fluids and tissues
if a drug overdose resulted in a cardiac arrest, what is cause and manner of death?
Cause: cardiac arrest
Manner: drug OD
respiratory arrest killed someone from carbon monoxide poisoning, what is the cause and manner of death?
Cause: respiratory arrest
Manner: carbon monoxide poisoning
Describe human performance forensic toxicology
- modifying human performance or behaviour
- analysis of blood, breath, or urine
Describe forensic drug testing
- determine drug use
- analysis of urine, oral fluid, sweat or hair
- not looking for amount of drug, just a yes or no presence of drug
ex. athlete, workplace drug testing
What is a forensic toxicologist?
- knowledge of the effects of poisoning on the body
- knowledge of drug metabolism (are we looking for presence of drug or active compounds?)
- knowledge of pharmacological actions of drugs
- knowledge of analytical chemistry
- able to correlate lab observations with clinical history, circumstances and symptoms shown by patient
What are the markers for heroin?
- morphine
- 6-acetyl-morphine
How does carbon monoxide change colour of blood?
cherry red colour
What questions must a forensic toxicologist be able to answer?
- Was a drug/poison found?
- What was it?
- How much was found?
- Was the amount of poison/drug sufficient to cause death or impairment?
- When and how was the poison/drug taken into the body? (what time and what route)
What is the toxicologist role?
Deal with death investigations:
- homicide
- suicide
- accidental
- natural
- undetermined
- see slide 11
Sominex
an old OTC sleep aid
What information is required to aid in interpretation where death has occurred ?
- age, gender and weight
- time and date of death/incident
- details of the last meal; actions between meal and onset of symptoms
- was person treated in the hospital?
- medication and drinking history
- symptoms prior to death
- pathologist’s findings/observations
- evidence found at the scene
- health of the deceased
- time delay between death and autopsy
What is postmortem redistribution?
- involves the distribution of drugs from the heart tissue to the cardiac blood
- cardiac blood levels may be significantly elevated
- levels from 2 sites (femoral and cardiac) allow for more accurate interpretation
- happens within 1 hour after death, up to 24 hours
- need to do an autopsy soon
What information do we need when it’s a living person?
- age, gender, weight
- signs & symptoms of impairment or intoxication
- admission of drug and alcohol use
- evidence found at the scene or on the victim or accused
Describe the parts of a toxicology exam
- screen or tentative identification
- confirmation (positive or negative test)
- quantitation (determining the amount - blood or liver)
- interpretation (was it the cause of death? was the level therapeutic, toxic or lethal?)
Describe “Continuity of exhibits”
*in the states it is called Chain of Custody
- Exhibits labelled by each possessor
- Sent by courier or hand delivered
- Adhesive tape used to seal containers
- Exhibits under lock and key at all times
- Transfer slips used
- No access to lab by unauthorized personnel
Types of blood we can analyze
- serum
- plasma
- whole blood
____ is the most reliable sample for interpretation of alcohol and drug impairment
blood
What does whole blood contain?
the cells
What does serum have?
no clotting factors
Plasma has _____ _____
clotting factors
Remember it by:
Plasma - Clot
PC
Describe how you ask for the blood
- ask for 15-20 mL
- 1% sodium chloride for preservative
*cocaine def needs a preservative bc enzymes in blood will breakdown cocaine
Describe urine samples
- noninvasive
- convenient to collect
- little or no sample prep
- drugs/alcohol found in higher concentrations
- longer detection periods compared to blood
*see slide 23 for pic
Describe the relative period of detection for GHB, Triazolam, Alprazolam, Diazepam
Detection period gets longer:
GHB < Triazolam < Alprazolam < Diazepam
What are some problems with urine samples?
- may not reflect level of impairment at time of incident
- some drugs break down in body making identification more difficult (extensively metabolized drugs - we will only see metabolite, not the parent drug)
- may be subject to adulteration or tampering
What can we determine from a urine sample?
**only the presence of a drug!
cannot determine when or how much
Exception: can be used to estimate BAC if period over which urine was collected is known
Describe pros of hair samples
- relatively non-invasive
- easy to collect
- no special storage requirements
- useful in determining long term drug use!!
*don’t need root of hair either, that is for DNA testing
Describe cons of hair samples
- not useful for detection of alcohol
- more costly than urinalysis
- environmental contamination may be an issue
- potential for racial and hair color bias (drugs preferentially bind to dark hair)
are hair samples useful for acute or chronic drug use?
chronic
1cm = 1 month
can get a timeline of how long they were using the drug
What is oral fluid?
essentially it’s saliva lol
How much oral fluid is collected?
1 mL
How can we stimulate oral fluid?
chewing on piece of paraffin, rubber band or glass marble
Describe oral fluid
- noninvasive
- easy to collect
- no medical personnel required to collect samples
- drug detection times similar to blood (so not as long as urine)
- only parent drug detected (bc no metabolites found in the mouth!!!)
What are some issues with oral fluid?
- requires sensitive analytical techniques
- limited data regarding interpretation or oral fluid levels
- recent smoking or oral consumption may complicate interpretation
**higher concentration in mouth doesn’t necessarily mean it’s impaired, it does mean recent drug use tho
Describe sweat for analysis
- noninvasive
- easy to collect
- patch impermeable to environmental contaminants
- each patch has unique ID number; therefore tamperproof
- only parent drug detected
Cons of using sweat analysis
- costly
- requires sensitive methods for detection
- entire patch is consumed in analysis (so none left over to re-do analysis)
- limited info regarding incorporation of drugs in sweat and significance of findings
how long do we have to analyze blood, saliva, urine, sweat, and hair?
blood and saliva - 1 day
urine - 3 days
sweat - 4-30 days
hair - 250 days
What samples can we get postmortem?
- blood
- urine
- liver
- stomach contents
- bile
- vitreous humor
- cerebrospinal fluid (CSF)
- kidney
- brain
- lung tissue
- hair and fingernails
- bone
- heart
- adipose tissue
- sites of injection
up to 100 times the drug concentration found in _____ compared to blood
liver
Liver may be only available specimen in who?
- decomposed bodies
- fire victims
- babies
When are stomach contents important?
if drug was ingested orally ( or we suspect it is orally)
What are stomach contents a measure of?
unabsorbed drug at the time of death
describe smells of different stomach contents
garlic = pesticides
burnt almond = cyanide
Describe bile
- major route of elimination for some drugs (ex. opiates)
- used for identification purposed only (b/c it’s a waste sample, can’t tell how much was taken or when it was taken)
What is vitreous humour?
- eye fluids
- only get 1-2mL/eye
- USED FOR ALCOHOL NOT DRUGS
- less subject to contamination and putrefaction
- limited quantity available
- clean sample
Describe CSF
- analyzed for alcohol when available
- less subject to contamination and putrefaction
- limited quantity available
- clean sample
what is putrefaction
the process of decay or rotting in a body or other organic matter
*so freeze exhibits immediately if submission is going to be delayed
