Midterm Flashcards
Describe strychine effect on body?
Short convulsions, between 30 seconds to 2 minutes. Usually there are between 1 and 10 attacks, each more intense than previous and shortening of time intervals.
What are street drugs?
They are impure and contain other compounds like baking soda or salt.
Medical use of arsenic?
First drug that was safe to treat syphilis.
Cosmetic use of arsenic?
Used to whiten the complexion in Victorian times, little chalk wafers advertised as “perfectly harmless”.
What is the route of exposure of arsenic?
Ingestion through food or drinks, inhalation in powder form or skin absorption.
True or False: Arsenic is hard to detect.
True, least subtle, odourless, tasteless
Hydrogen Cyanide (HCN) in liquid form
Prussic Acid
How is pure HCN gas made?
Mixing acid with cyanide salts.
T/F Sodium and potassium salts of HCN are white.
True
Cyanide chemical in food
Cyanogenic Glycoside
Cyanide is most commonly detected
in fire deaths
Route of administration is important for
determining toxicity and time frame
In fire deaths you should first test for
carbon monoxide. You test for cyanide if carbon monoxide is low. If you d find carboxyhemoglobin in the blood then you can confirm that the person died from the fire. If not, it can turn in a homicide case due to cover ups.
Mathieu Orfila
Father of toxicology, performed Marsh test on soil and on the body. Found that the previous test was faulty and Marie was convicted.
Lab worker forensic toxicologist vs. Analytical forensic toxicologist
Lab worker more hands on duties, analytical toxicologists interpret the results and go to court to provide expert opinions
Letters of Opinion
Provide additional information than a regular report, no analysis is done but an opinion is provided. Example - sexual assault case that happened months ago, an opinion can be formed on background data
Non-biological samples might be easier to test for than biological samples because
they can be found in high concentrations and deterioration does not occur as quickly. When you have a limited amount of biological sample you might want to test non-biological sample first for an insight for what to test for.
What toxicological tests are required are dependent on
specific case history and analytical capabilities
Fentanyl laced cocaine
Fentanyl (opioid) and cocaine are two different drugs, if you are not used to fentanyl snorting it can lead to serious side effects
What is the purpose of testing in death investigations?
Test for drugs
What analysis is suitable in death investigations?
The test should be able to detect the drug under suspicion, dependent on case history and analytical capabilities
Guideline for interpreting the findings in death investigations?
Understanding how the drug works and how it was used, how it affected the body.
Inquests are mandatory for
occupational/workplace accidents and deaths in custody
Postmortem forensic toxicology homicide protocol
Full drug screening within the case to look for behavioural or cause of death. This protocol is to prevent questioning and suspicion in trials - protect credibility.
Types of death investigations (coroner’s cases)
- No anatomical cause of death
- Cause of death established but impairment may be an issue
- SIDS (<2 years old)
- Occupational/workplace accidents
- Deaths in custody
- Aviation deaths
- Fatal MCV’s
- Fire death investigations
Coroner cases: No anatomical cause of death
If enough medical history is known to confidently say they died of medical reasons drug testing is not needed
Coroner cases: Cause of death established but impairment might be an issue
The Cause of Death is known but the circumstances are problematic. Falls to death - were they intoxicated?
SIDS
- Under 2 years old
- No anatomical cause of death
- You have to rule out drug use so a full toxicology screening is done, rarely a drug will be found
- Test to exclude toxicology as the cause of death, if the drug is found and you cannot exclude then the case becomes homicide case
T/F: Pathologists collect blood samples.
True
Adequate volumes of analysis is important because
Multiple tests might be needed
Quality assurance in specimen collection
Important to have the best sample to have the best interpretation and results, a specimen collected with QA methods and storage and handling increases accuracy as well as testing method.
Antemortem blood NOT same as
Postmortem blood
Antemortem blood sample
Is IDEAL. Just before they die, very rare.
Postmortem blood quality
diminishes over time since compounds in blood start to break down.
Ideally, a minimum of 2 blood specimens should be collected
from peripheral and central sites, due to postmortem redistribution drug concentrations might be different on different sides of the body.
Ideally, a minimum of 2 blood specimens should be collected
from peripheral and central sites, due to postmortem redistribution drug concentrations might be different on different sides of the body.
Blood Collection Guidelines
- Ideally, a minimum of two blood specimens should be collected.
- Anatomical site of collection should be noted.
- Sample should be collected from an intact vessel.
Sample should be collected from an intact vessel
- Know that the site is not contaminated
- Decomposition of organs might cause rupture and mingles that contaminates the blood and site.
Central site
Heart
Peripheral site
- Femoral vein that goes down the leg
- Iliac vein
**Peripheral sites are less prone to PMR
What is a hematoma
Extravascular blood clot
Be careful about hematomas because
hematomas take a while to form so interpretations are tricky. Also there might be a delay between the incident and hematoma formation.
Hematoma blood samples
might be useful as drugs are protected from metabolism and analysis will indicate what drugs were present in the blood at the time of the formation
T/F: Urine samples cannot identify if drugs were present at the time of death.
True
T/F: Urine samples cannot identify long term drug use.
False, long-term drug exposure can be identified as durgs/metabolites can accumulate in the urine for days/hours.
Use urine sample for
know what drugs to test for in blood. Once you determine all toxins you can choose most dangerous toxins in the body and test for them in the blood to see if they were there at the time of death.
Detection in urine and blood
Some drugs are metabolized so quickly they may only be detected in urine (heroine=metabolite morphine)
T/F: Urinary drug concentrations may bear little to no correlation with the effects being experienced by the individual at the time of death.
True
Urine qualitative analysis
presence of the drug indicates only that the poison was present in the blood of the individual some time before death.
No longer subject to metabolism
Urine
Gastric contents useful for pathologists because
visual examination for tablets as well as odours of cyanide or alcohol.
Caution with Gastric Contents
Drugs administered by other routes may also diffuse into stomach contacts by blood. (morphine injection traces found in stomach)
Gastric content interpretation
Generally qualitative and useful for further analysis.
The presence of many tablets in the stomach
may be an indication of overdose and it can be quetsioned if it is an accidental or suicidal OD.
Caution with Gastric Contents and Tablets
some slow-release formulations can remain in the stomach for an extended period of time and it might not necessarily be overdose.
Define ghost tablets
The empty tablet shell remains and there’s no drugs in it, can look like OD even though it isn’t. Blood drug concentration will be low even if you find many tablets, that’s how you identify it.
Where does drug metabolism occur?
Liver
Why is the detection in liver easier?
both parent compounds and metabolites may be present in higher concentrations in liver than in blood
Liver sample collection benefit
Even if a body is decomposed, we can still obtain (3 cm x 3 cm) liver sample.
Limitation of Liver
Drugs are not uniformly distributed throughout the liver, interpretation is affected by the section of the liver used as sample.
Define Vitreous Humour
Fluid that occupies the space between the lens and the retina of the eye
Vitreous Humor Benefits
Protected longer from trauma to the body and durable to putrefaction, charring and microorganisms.
Vitreous Humor is useful in cases where
- decomposition is advanced
- body is exhumed
- traumatic accidents
- fire deaths
Vitreous Humor is useful in cases where
- decomposition is advanced
- body is exhumed
- traumatic accidents
- fire deaths
Limitation of Vitreous Humor
Blood:Vitreous ratio may not be known, drug concentrations may vary among them.
Autopsy Samples of Limited Value
- Spleen squeezings
- Chest cavity blood
- Gutter blood
- Samples taken after transfusion in hospital
Chest Cavity Blood Sample
A “contaminated” blood sample that may contain fluids from the stomach, heart, lungs.
Chest Cavity Blood Sample most likely collected if
Traumatic injury or advanced decomposition
Gutter Blood
not enough blood collected to extra fluid from autopsy is collected
Non Biological Submission Samples
- Containers found at the scene
- Syringes and spoons
- Unidentified tablets or liquids
When to use non-biological samples
When we do not have enough blood samples and use to direct analysis of biological samples
Non-biological samples may indicate
nature of the substance that may have been ingested, inhaled or injected
Storage and Handling Guidelines
- Proper specimen handling (biohazard)
- Identification of samples
- Specimens should be delivered to lab as soon as possible
- Storage areas should be secure (iris scanners)
- Specimens should be analyzed as soon as possible
- Sample containers should be sterile
- Sample should be in well sealed container
- Usage of preservatives and anticogulants
Storage and Handling: Identification of Samples
- Ensure items are intact and properly sealed
- Establish continuity of items as chain of custody is important in court and for credibility
- Accurate description of items in paperwork
If sample containers are not sterile
microorganisms can affect interpretation
Refrigeration vs. Freezing
- Both inhibit bacterial action, especially freezing.
- Freezing increases prep time (Do not freeze while actively using freeze after just in case any tests need to be done)
- Freeze-thaw cycle may promote breakdown
Use of preservatives and anticogulants are good for
pipetting as they prevent clotting
Preservatives
Sodium fluoride
Anti coagulants
Sodium citrate and potassium oxalate
Name the 2 processes of decomposition.
Autolysis and Putrefaction
Define Autolysis
The breakdown of cellular material by enzymes, happens immediately after death
Define Putrefaction
The destruction of soft tissues by the action of bacteria and enzymes.
Putrefaction Increases When
Traumatic deaths demonstrate increased putrefaction, ruptured body parts release bacteria
Decomposition causes
- Fewer samples available for collection. (Liquefaction of vessels and tissue/desiccation of fluids)
- Quality of samples are diminished.
Putrefaction produces alcohols
- ethanol
- n propanol
If both present and ethanol more than 100mg/100mL could indicate drinking before death
If less than 100mg/100mL of ethanol and n propanol present most likely putrefaction
1 mg / L
1 ug / mL
Define Postmortem Redistribution
Physiological process of drugs release from one area of the body into another area after death.
What can be observed with PMR?
Increased concentrations of some drugs and site dependent concentration differencies.
Central blood samples and PMR
Central blood samples might have higher concentrations of certain drugs than peripheral blood samples but not always.
Why do we care about PMR?
May result in an inaccurate representation of what the blood concentration was at the time of death compared to a higher blood concentration found at autopsy.
What causes PMR?
- cell death
- putrefaction
- diffusion of the unabsorbed drug in the stomach to the inferior vena cava
- diffusion from high concentration areas to close proximity vesses
- body position and movement after death
- resusitacion
Factors to consider with PMR
Time of collection and site of collection
