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Year 4 - Toxicology > Forensic Overview > Flashcards

Forensic Overview Flashcards

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

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2
Q

What does toxicology involve?

A
  • identification
  • quantitation
  • interpretation
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3
Q

What are the different levels of drug concentrations?

A
  • therapeutic
  • toxic
  • lethal
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4
Q

What are 2 subspecialties of toxicology?

A
  • clinical toxicology

- forensic toxicology (dealing with crimes man)

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5
Q

List the 3 areas of forensic toxicology

A

1) Postmortem forensic toxicology
2) Human performance forensic toxicology
3) Forensic drug testing

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6
Q

Describe postmortem forensic toxicology

A
  • cause and manner of death

- analysis of body fluids and tissues

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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

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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

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9
Q

Describe human performance forensic toxicology

A
  • modifying human performance or behaviour

- analysis of blood, breath, or urine

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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
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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
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12
Q

What are the markers for heroin?

A
  • morphine

- 6-acetyl-morphine

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13
Q

How does carbon monoxide change colour of blood?

A

cherry red colour

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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)
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15
Q

What is the toxicologist role?

A

Deal with death investigations:

  • homicide
  • suicide
  • accidental
  • natural
  • undetermined
  • see slide 11
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16
Q

Sominex

A

an old OTC sleep aid

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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
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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
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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
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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?)
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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
Q

What does serum have?

A

no clotting factors

26
Q

Plasma has _____ _____

A

clotting factors

Remember it by:
Plasma - Clot
PC

27
Q

Describe how you ask for the blood

A
  • ask for 15-20 mL
  • 1% sodium chloride for preservative

*cocaine def needs a preservative bc enzymes in blood will breakdown cocaine

28
Q

Describe urine samples

A
  • 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
Q

Describe the relative period of detection for GHB, Triazolam, Alprazolam, Diazepam

A

Detection period gets longer:

GHB < Triazolam < Alprazolam < Diazepam

30
Q

What are some problems with urine samples?

A
  • 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
Q

What can we determine from a urine sample?

A

**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
Q

Describe pros of hair samples

A
  • 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
Q

Describe cons of hair samples

A
  • 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
Q

are hair samples useful for acute or chronic drug use?

A

chronic

1cm = 1 month

can get a timeline of how long they were using the drug

35
Q

What is oral fluid?

A

essentially it’s saliva lol

36
Q

How much oral fluid is collected?

A

1 mL

37
Q

How can we stimulate oral fluid?

A

chewing on piece of paraffin, rubber band or glass marble

38
Q

Describe oral fluid

A
  • 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
Q

What are some issues with oral fluid?

A
  • 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
Q

Describe sweat for analysis

A
  • noninvasive
  • easy to collect
  • patch impermeable to environmental contaminants
  • each patch has unique ID number; therefore tamperproof
  • only parent drug detected
41
Q

Cons of using sweat analysis

A
  • 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
Q

how long do we have to analyze blood, saliva, urine, sweat, and hair?

A

blood and saliva - 1 day
urine - 3 days
sweat - 4-30 days
hair - 250 days

43
Q

What samples can we get postmortem?

A
  • 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
Q

up to 100 times the drug concentration found in _____ compared to blood

A

liver

45
Q

Liver may be only available specimen in who?

A
  • decomposed bodies
  • fire victims
  • babies
46
Q

When are stomach contents important?

A

if drug was ingested orally ( or we suspect it is orally)

47
Q

What are stomach contents a measure of?

A

unabsorbed drug at the time of death

48
Q

describe smells of different stomach contents

A

garlic = pesticides

burnt almond = cyanide

49
Q

Describe bile

A
  • 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
Q

What is vitreous humour?

A
  • eye fluids
  • only get 1-2mL/eye
  • USED FOR ALCOHOL NOT DRUGS
  • less subject to contamination and putrefaction
  • limited quantity available
  • clean sample
51
Q

Describe CSF

A
  • analyzed for alcohol when available
  • less subject to contamination and putrefaction
  • limited quantity available
  • clean sample
52
Q

what is putrefaction

A

the process of decay or rotting in a body or other organic matter

*so freeze exhibits immediately if submission is going to be delayed

Year 4 - Toxicology (24 decks)

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