Forensic Overview Flashcards
(52 cards)
1
Q
What is toxicology?
A
the analysis of body fluids and tissue for the presence of drugs and poisons
ex. urine, blood, kidney or liver tissue
2
Q
What does toxicology involve?
A
- identification
- quantitation
- interpretation
3
Q
What are the different levels of drug concentrations?
A
- therapeutic
- toxic
- lethal
4
Q
What are 2 subspecialties of toxicology?
A
- clinical toxicology
- forensic toxicology (dealing with crimes man)
5
Q
List the 3 areas of forensic toxicology
A
1) Postmortem forensic toxicology
2) Human performance forensic toxicology
3) Forensic drug testing
6
Q
Describe postmortem forensic toxicology
A
- cause and manner of death
- analysis of body fluids and tissues
7
Q
if a drug overdose resulted in a cardiac arrest, what is cause and manner of death?
A
Cause: cardiac arrest
Manner: drug OD
8
Q
respiratory arrest killed someone from carbon monoxide poisoning, what is the cause and manner of death?
A
Cause: respiratory arrest
Manner: carbon monoxide poisoning
9
Q
Describe human performance forensic toxicology
A
- modifying human performance or behaviour
- analysis of blood, breath, or urine
10
Q
Describe forensic drug testing
A
- 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
11
Q
What is a forensic toxicologist?
A
- 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
12
Q
What are the markers for heroin?
A
- morphine
- 6-acetyl-morphine
13
Q
How does carbon monoxide change colour of blood?
A
cherry red colour
14
Q
What questions must a forensic toxicologist be able to answer?
A
- 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)
15
Q
What is the toxicologist role?
A
Deal with death investigations:
- homicide
- suicide
- accidental
- natural
- undetermined
- see slide 11
16
Q
Sominex
A
an old OTC sleep aid
17
Q
What information is required to aid in interpretation where death has occurred ?
A
- 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
18
Q
What is postmortem redistribution?
A
- 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
19
Q
What information do we need when it’s a living person?
A
- 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
20
Q
Describe the parts of a toxicology exam
A
- 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?)
21
Q
Describe “Continuity of exhibits”
*in the states it is called Chain of Custody
A
- 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
22
Q
Types of blood we can analyze
A
- serum
- plasma
- whole blood
23
Q
____ is the most reliable sample for interpretation of alcohol and drug impairment
A
blood
24
Q
What does whole blood contain?
A
the cells
25
What does serum have?
no clotting factors
26
Plasma has _____ _____
clotting factors
Remember it by:
Plasma - Clot
PC
27
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
28
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
29
Describe the relative period of detection for GHB, Triazolam, Alprazolam, Diazepam
Detection period gets longer:
| GHB < Triazolam < Alprazolam < Diazepam
30
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
31
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
32
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
33
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)
34
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
35
What is oral fluid?
essentially it's saliva lol
36
How much oral fluid is collected?
1 mL
37
How can we stimulate oral fluid?
chewing on piece of paraffin, rubber band or glass marble
38
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!!!)
39
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
40
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
41
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
42
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
43
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
44
up to 100 times the drug concentration found in _____ compared to blood
liver
45
Liver may be only available specimen in who?
- decomposed bodies
- fire victims
- babies
46
When are stomach contents important?
if drug was ingested orally ( or we suspect it is orally)
47
What are stomach contents a measure of?
unabsorbed drug at the time of death
48
describe smells of different stomach contents
garlic = pesticides
| burnt almond = cyanide
49
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)
50
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
51
Describe CSF
- analyzed for alcohol when available
- less subject to contamination and putrefaction
- limited quantity available
- clean sample
52
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
