Burning and Blasting - Lecture 19 Flashcards
What are the 4 stages of heat changes to the body?
Stage 1 - Pugilistic Posture
Stage 2 - Soft Tissue Modification
Stage 3 - Bone Modification
Stage 4 - Bone Calcination
Explain Stage 1
- body begins to dry out causing muscles to shrink beginning with small ones in fingers and toes
- body will begin to bend at limbs and joints
- appendages closest to the fire begin to modify first
Explain Stage 2
- soft tissue closest to the fire begins to modify
- charring and burning and fats and liquids in the body begin to boil
- skin splits and organs push out
- thinner areas removed first
- neck and chewing (masticating) muscles stay longer
Explain Stage 3
- bone will begin to dry out and char
- low temp 200-700 degrees celsius
- organic components beginning to burn away resulting in charing
- heat line appears which is a distinct line between earlier and later stages of burning
- ultraviolet light used to see a better picture of heat line
Explain Stage 4
- all of the organic component has burned away leaving only mineral component
- high temp 800 degrees celsius +
- colour ranging from dark grey to white
- lighter the bone the less organic material
- bones begin to crack (crescent lines)
- also transverse or oblique cracks
- longitudinal breaks
- checkerboard cracking on cranial or flat bones
- bones will warp and shrink due to drying out
What is the shrinkage range for low temp damage?
no more than 2%
What is the shrinkage rate for 700-800 degrees celsius?
1-3%
What is the shrinkage rate for 800+ degrees celsius?
5-15% but has been as high as 25%
Can low temperature burning look like high temperature burning and vice versa?
yes it is all due to the amount of time a bone is exposed
What crimes can be associated with low temperature fires?
- arson
- getting rid of evidence
What activities can be associated with high temperature fires?
- fatal fire scene like car or house fire
- cremation
Describe the characteristics of arson.
- use of accelerants that can cause more burning in areas the accelerant landed
- confined spaces can result in the inability to assume the pugilistic posture
Describe the characteristics of someone using fire to get rid of evidence.
- in cases of dismemberment the kerf becomes completely destroyed by fire
- false starts and kerfs walls and floors are unaffected
Describe the characteristics of a fatal-fire scene. How hot can they get?
- difficult to distinguish human remains from other debris
- house fire can get up to 815 degrees celsius or greater
- car fires can get as high as 900 degrees celsius
Describe the characteristics of cremation.
- between 980-1090 degrees celsius
- soft tissue disintegrates to ash after 2 hours
- complete calcination of bone
What mixed forces and mechanisms is blasting a product of
Forces
- compression
- shearing
- bending
Mechanisms
- high velocity projectile
- blunt
- sharp
- thermal
What are the 4 types of blast traumas?
- primary
- secondary
- tertiary
- quaternary
Describe Primary Blast Traumas.
- barometric changes from the blast wave can pick up someone and throw them away, burst ear drums, lungs, and bowels
- amputation of long bones and decapitation can occur
Describe Secondary Blast Traumas.
- someone who is further away can be pelted by shrapnel or impaled by glass
- high velocity BFT from pieces of building
- radiating and concentric fractures
Describe Tertiary Blast Traumas.
- large object falling on on the person being thrown into things resulting in BFT
- comminuted fractures
- butterfly fractures mainly to ribs
Describe Quaternary Blast Traumas.
- miscellaneous injuries
- burns
- smoke inhalation
- dust/ash/debris in eyes, nose, and throat
