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what is forensic toxicology?

the application of toxicological principles (i.e., the harmful effects that chemicals, substances, or situations have) to cases before the court

what is a chemical?

any substance that is produced in a reaction that involves changes to atoms or molecules

what are organic chemicals?

carbon containing

what are the types of chemicals?

1. poisons/environmental chemicals (hydrogen sulphide, cyanide, etc.)
2. chemicals of abuse (depressants, hallucinogens, etc.)

what is chemical trauma?

trauma caused directly or indirectly by the application of chemical agents to tissues

what is direct chemical trauma?

* direct destruction of tissues (e.g., tattoo removal with chemical produce or hole in the mouth caused by drug use)
* mechanisms (red/ox, corrosion)
* alveolar destruction

what is indirect chemical trauma?

* infection
* introduction via the route (needle or inhalation)
* introduction via the agent (aspergillosis infection from inhaled cocaine)
* asphyxia
* alveolar destruction
* aortic dissection

what is asphyxia and how can it happen?

it is the loss of oxygen due to:

* suffocation = blockage of airway (failure of O2 to reach blood → choking, environmental)
* strangulation = blockage of blood vessels (failure of blood supply to reach brain by occlusions of neck vessels → hanging)

how can chemicals lead to asphyxia?

strangulation route = blockage of blood vessels (rare for suffocation to occur due to chemicals)

what is alveolar destruction?

destruction of alveoli due to chemical use.

* can lead to Hemosiderosis (lots of iron to blood)
* can lead to thick fibrous tissue in lungs (inability to exchange blood effectively + less elasticity (can’t open/close))

what is aortic dissection and what is it’s forensic significance?

* Vessels layers separate
* Can be caused by stimulant use OR blunt force trauma


* Forensic significance: in MVA, was it the collision or drug use that led to aortic dissection?
* Important for cause and mechanism of death

what factors determine the severity of chemical trauma?

* chemical agent (strong bases >>)
* time or timing of exposure (length, developmental window)
* tissue exposed/penetrated
* delivery method (IV, inhaled, ingested → IV is quickest)
* quantity and concentration

what is wrong with this image?

* this is an example of “crack lung”
* there is a mass area of whitened, damaged, scarred tissue in the lungs
* the white areas should not be there

This image is a CT scan of someone’s lungs. Describe what you see.

* lungs were exposed to a chemical agent = asbestos
* asbestos are very easy to breathe in and they become invaginated in the tissues, so they cannot get out
* the image shows a build-up of asbestos in the mucous tissue of the lungs

how can the timing of chemical use impact severity of trauma?

* acute
* depression of function (drug acting on brainstem will affect respiration, heart rate, and balance → fentanyl)
* chronic
* receptor sensitivity changes = tolerance
* cell death leads to structural loss, and loss of function (alcohol neuropathy)

this is the development of an individual's brain. Explain whether this is healthy or unhealthy and why.

* unhealthy → looks like alcoholic person
* a lot of open black scapes (sinuses)
* ventricles are much bigger than normal
* less white matter (less communication in the brain)
* structural loss → loss of function

how can the timing of alcohol affect the liver?

* middle liver = medium-term abuse (fatty liver/statosis) = reversible with lifestyle changes + drugs
* right liver = long term abuse (cirrhotic liver) = irreversible
* healthy tissue replaced with fibrous/scar tissue

what is fetal alcohol syndrome?

* pregnant woman drinks during developmental window
* developmental window = period of time during development with rapid differentiation occurs
* prior to 8th week in utero
* rapid development + organ formation
* sensitive to birth defects → very likely to lead to incompatible with life
* after the 8th week in utero
* neurological impairment possible
* 3rd trimester fetus can redirect blood supply and spare brain
* prenatal growth restriction (not growing to healthy sizes and masses)

what are some features of fetal alcohol syndrome?

* flat midface
* short nose
* indistinct philtrum
* low nasal bridge

what can fetal alcohol syndrome lead to?

learning disorders: dyslexia, visual/auditory/verbal processing disorder, ADHD

how can the delivery method impact the severity of the chemical trauma?

IV drug injection (overdose likely due to direct exposure -- infection can occur)

pulmonary delivery (inhaling) -- affects respiratory centers → lung edema → death

how can the quantity and concentration of the drug impact the severity of the chemical trauma?

1. pharmacokinetics = dose → concentration vs time
2. pharmacodynamics = effect vs concentration


1. effective dose - desired therapeutic, recreational effect
2. overdose - effect is too strong, or effect is on wrong tissues
3. PK-PD = dose → effect vs time

what are the signs of an overdose and what do those indicate?

signs: nausea, tremors, drowsiness, changes in heart rate, changes in eye movement

indicates: seizure activity, respiratory distress, cardiac dysrhythmia, coma

what is the integumentary system?

1. skin (keratinized/external) or unkeratinized/internal (e.g., mucous membranes: GI, vagina, bladder)
2. appendages to skin (e.g., hair, nails, sweat glands)

what are the functions of the integumentary system?

* barriers to pathogens
* heat regulation + cooling
* water distribution/movement

what are the 3 layers of the skin?

1. epidermis (protection of pathogens and regulation of water and movement)
2. dermis (responsible for cushioning and protecting the body)
3. hypodermis (subcutis) (protection and cushioning, heat regulation, connecting to muscles and bones)

what are the 5 layers of the epidermis?

superficial to deep:


1. stratum corneum
2. stratum lucidum
3. stratum granulosum
4. stratum spinosum
5. stratum basale

what are the 3 layers of the dermis?

superficial to deep:


1. papillary dermis
2. reticular dermis
3. adipose tissue layer

what is a burn?

injury caused by the application of any force or energy that releases heat

what erythema

redness of skin or mucous membranes due to increased blood flow

what is edema?

swelling caused by loss of fluid from small blood vessels into tissues

what is hyperemia?

excess of blood and fluid in vessels supplying an organ or tissue

what is a blister and where is it formed?

fluid filled sac formed between epidermis and dermis

what are the 6 categories of burns based on the agent?

1. flame = skin in direct contact with flame
2. contact = skin in direct contact with a hot surface
3. radiant = skin exposure to heat wave (indirect)
4. scalding = skin exposed to hot liquid
5. microwave = skin contact with electromagnetic wave
6. chemical = skin contact with caustic chemical agents

what are the 4 categories of burns based on severity?

1. first degree = superficial epidermis, erythema and edema, pain (sensory neurons intact), no scars
2. second degree = epidermis and dermis, blistering, pain, no scars
3. third degree = burned area white, loss of sensation, severe scarring
4. fourth degree = incineration of tissue (black tissue), complete destruction of epidermis, dermis and subcutaneous tissue, can include bone

what are the factors that determine the severity of the burns?

* intensity - amount of heat transferred to skin (regardless of agent)
* duration (regardless of agent)
* underlying conditions (e.g., less adipose tissue)
* presence and type of clothing (can protect or adhere to burn)

what factors determine the survivability of a burn?

* age (older = less skin to absorb the heat) -- rly young and old are always more vulnerable
* degree of burn
* percentage of body surface
* rule of 9 for adults (head x1, arms x1, torso x4, legs x2)
* rule of 5 for children (head x2, arms x2, torso x6, legs x3)

what is the difference between ante/peri- versus post-mortem burns?

* soft tissue is difficult to distinguish and can share histological features
* bone can show fracture characteristics (longitudinal fractures) that are associated with pugilistic contracture (flexing of hands = fracture = looks like body parts are missing)

What is environmental trauma?

Morbidity and mortality due to tissue damage caused by environmental conditions, namely hypothermia, hyperthermia, drowning, and lightning

what is hypothermia?

core body temperature is below 35 degree C due to exposure to cold environments for prolonged periods of time + susceptibility

what factors determine the survivability of hypothermia?

* age
* sex
* body habitus
* water exposure (good conductor of heat compared to air - boiling water VS hand in oven)

what are the physical symptoms of **mild** hypothermia?

* maximal shivering


* amnesia
* ataxia = difficulty performing tasks

what are the physical symptoms of **moderate** hypothermia?

* reduced consciousness


* shivering stops, dilated pupils
* cardiac arrhythmia
* coma

what are the physical symptoms of **severe** hypothermia?

* loss of voluntary movement + reflexes


* no response to pain
* hypotension, bradycardia (slow heart rate)

how can hypothermia lead to morbidity and mortality?

* depressed respiration
* muscle stiffness = falls
* ulcers and focal GI bleedings
* pneumonia
* kidney damage
* myocardial degeneration

what is hyperthermia?

core body temperature above 40.5 degrees C

what are factors that determine the sensibility and severity of hyperthermia?

* age
* social determinants of health (SES, social support)
* pre-existing conditions
* alcoholism
* cerebral or cardiac atherosclerosis
* Rx drugs (e.g., antidepressants)
* obesity

what are the symptoms of **mild** hyperthermia?

* heat cramps
* heat exhaustion

what are the symptoms of **severe/life-threatening** hyperthermia?

heat stroke

* life threatening without treatment
* mortality = 76% with treatment (forensically an issue when weather gets more severe - global warming)

how can hyperthermia lead to mortality and morbidity?

* brain damage
* respiratory failure
* heart failure
* pancreas + kidney damage
* intestinal damage

define drowning

when oxygen is replaced with water in the body

what is the effect that the type of water can play on drowning?

freshwater (hypotonic = loss solute)

* passes more quickly through alveoli
* increases blood volume

saltwater (hypertonic = more solute)

* draws water into alveoli from blood
* decreases blood volume

what can drowning lead to?

hypoxia

* results in damage to tissues (less oxygen reaches them)
* cerebral anoxia = oxygen not reaching brain
* death

what are the gender differences in drowning?

* men more likely to drown
* more access to aquatic sites
* high risk behaviours
* alcohol consumption at sites

how does the temperature of the water impact drowning?

* cold water = slows down
* protective - “diving reflex”
* warm water = speeds up
* irreversible cerebral anoxia in 3-10 minutes
* heated water = speeds up the most
* hot tubs, whirlpool deaths
* often accompanied by alcohol/intoxication
* cerebra anoxia faster
* hypotension → faining/slipping under water (unnoticed)

what is near-drowning and how does it occur?

* significant morbidity
* survival for at least 24 hours post rescue
* due to
* sequelae of anoxia
* pulmonary edema
* blood in urine
* sepsis
* cerebral edema = death

what is OHM’s law?

I = V/R

* I current (flow of electric charge)
* V voltage (electromotive force)
* R resistance (opposition to the flow of charge

\*high resistance = low current

what factors determine the severity of electrocution?

* nature of current (AC (most electronics), DC, and flow)
* amount of current (A)
* voltage (V)
* path through the body
* time of exposure
* condition of circuit (wet, dry (more resistance), grounded to earth)
* resistance of body, clothing, ground, etc.

how does a current flow?

follows shortest path (not path of least resistance)

* path varies with current entry and exit site
* morbidity will depend on path
* fatal paths usually cross brain or heart (interruption of electrical activity)

How much current is sufficient for a cardiac arrest?

2A (2000mA)

(note: 100mA in a lightbulb)

What is the difference between low and high voltage on the severity of the electrocution?

Low voltage

*

what is force?

(F = ma) force is what sets an object in motion

what is kinetic energy?

(KE = 1/2mv^2) the energy an object has because it is in motion

true or false: mass has a greater contribution than speed

false

why are injuries important in forensics?

they tell you information about the situation, objects, and those involved

what are the types of blunt force injuries?

* abrasions = friction
* avulsions = something torn away
* fractures = broken
* contusions = bruise
* lacerations = torn tissue

what are the differences between raccoon eyes and black eye?

black eye is caused by blunt force trauma locally applied; raccoon eyes due to cranial fracture (circular + uniform black eyes)

both are contusions

what are the some information you can get from fractures?

OLD ACID

Open or closed

Location

Degree

Articular extension

Communication and pattern

Intrinsic bone quality

Displacement, angulation, rotation

what is the difference between open and closed fractures?

open fractures = broken end of bone passes through skin

closed fracture = skin is not lacerated

what are the degrees of fractures?

complete fractures: transect the bone, separation of bone segments

incomplete fractures: bone bends and tears but is not transected

what is articular extension?

fracture enters joint space (e.g., rotator cuff injury with articular extension)

list the patterns and comminution of the following fractures:

normal

transferse

oblique

spiral

comminuated

avulsion

impacted

fissure

greenstick

what is intrinsic bone quality?

underlying conditions that predispose bones to fracture (like osteoporosis/osteopenia, osteogenesis imperfecta)

must test for and rule out conditions where there is a suspicion of child or elder abuse

What is displacement, angulation, and rotation of a fracture?

Displacement – bone moved away from natural position

Angulation – bone moved away and shifted by a discernable angle

Rotation – bone rotated along axis (with or without displacement or angulation)

what is the difference between a laceration vs a stab?

Stab is deeper than it is wide

What can projectile injuries show?

Entry and exit wounds can show direction = position of those involved

What are mixed force injuries?

Injuries resulting from trauma inflicted by more than one type of force or energy

* chop wounds = shard and blunt
* crush wounds = blunt and sharp
* pneumothorax = blunt and sharp

what is patterns of injury?

Tells us information about the circumstances/sequence of events

What are patterned injuries?

Tell us information about the object when the imprint of the object is stamped onto the skin

what is the difference between “patterned injuries” and “injury patterns”?

* patterned injuries = tell us information about the object
* injury patterns = tells us about the circumstances

What are defensive wounds?

* damage to the hands, forearms, feet, inner thighs
* tells us the victim was conscious

What do you need to consider with MVCs?

* bumper height
* compression and avulsion injuries in almost 60% of MVC pedestrian deaths
* directionality of damage → directionality of impact

what is inguinal stretching?

* MVC
* blunt force trauma
* from behind or oblique collision
* inguinal ligament overstretched, pulls skin and fascia (bleeding into tissues)

Where are IV drug injection sites usually?

* when veins in arms cannot be used, they will use veins of legs and feet
* harder to find in thigh and leg
* often feet, between toes
* popliteal area uncommon because it’s hard to reach

what is dismemberment?

* sharp post-mortem trauma
* tool marks remain on bone
* often done to hide identification of body or body disposal

e.g., striation means something was going back and forth (like a saw)

What is a pelvic ring fracture?

separation of pelvic bones (SI joint or pubic symphysis)

* causes external over-rotation

what can lead to sudden natural death?

* undiagnosed/untreated pelvic neoplasia (can be due to stigma)
* STIs
* HIV = cervical cancer
* HPV = infection → sepsis
* UTIs
* sepsis

What is prostate cancer?

* older men
* hardens prostate = reduction in urinary outflow
* rule out = enlarging of prostate and urinary outflow reduction

What is ovarian cancer?

* most difficult to diagnose
* needs different imaging techniques
* most commonly originates in epithelial layers of ovary
* older women
* frequently metastases

what is cervical cancer?

* cancer of cervix and uterus
* one source is HIV
* higher rates in highly religious people and antivaxxers

What are complications of pregnancy?

* assault
* vulnerable population for violence
* sudden natural death
* hemorrhage (ectopic - fetus growing in a place other than the uterus)
* infection and sepsis
* complications of abortion
* obstetric fistula (obstructed labour)

what are the 3 types of death?

1. somatic


1. heart and lungs stop working = whole systems failing
2. neurologic


1. brain death = irrecoverable
3. cellular

what are the 3 types of cellular deaths?

* apoptosis = preprogrammed cell death
* necrosis = cellular and tissue localized death due to external causes
* autolytic = enzymatic non-programmed self-destruction after somatic death

what are the 2 phases of decomposition?

1. intrinsic (internal)


1. cellular
2. autolysis
3. bacterial
2. extrinsic (external)


1. can be physically seen
2. changes to soft tissue
3. used to determine post-mortem internal/time since death

what is autolysis

* “cell death”
* cellular processes that keep native enzymatic activity in check stops
* leads to lack of O2 and nutrients to cells

what are the 4 extrinsic stages of the decomposition process?

1. fresh


1. autolysis
2. mortis triad
2. early decomposition


1. bloating
2. skin slippage
3. purging
3. advanced decomposition


1. compression/deflation
2. initial skeletonization
4. skeletonization/mummification


1. skeletal elements more than 75% exposed OR
2. skin becomes mummified

what is the mortis triad?

1. livor mortis (pooling/settling of blood to the lower point (fixed lividity)
2. algor mortis (cooling or warming of body)
3. rigor mortis (stiggin of the body post-mortem)

how can algor mortis be used to estimate PMI?

in a climate-controlled environment, it will change 2 degrees F/hr

very variable (if hotter could be higher rate)

how long will rigor mortis be seen for?

appear the first 30 min → 2 hours after death

* completely fixed at 12 hours
* starts relaxing 24-36 hours post mortem

what is the megyesi scale?

scale used to measure decomposition after the first 72 hours

* examines: head + neck, torso, limbs (upper + lower togethers)
* lowest possible score = 3 (fresh in all 3 areas)
* highest score = 35 for skeletonized