Transcript Routes of Attack

Chemical Agents
Routes of Entry and the
Body’s Defences
Routes of Entry
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Skin contact
Inhalation
Ingestion
Injection
Inhalation
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The lung is the most vulnerable
part of the body
Even small concentrations of a
toxic agent in the atmosphere
being inhaled can, after a
period, develop a build-up of
toxicant in the body
Skin Contact
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Has many layers of protection
and does not allow solid or
gaseous substances to be
absorbed, so only liquids
provide a hazard
Skin of hands, arms & legs
usually has some breaks in its
surface, do risk of entry by
injection is a possibility
Ingestion
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Gastrointestinal tract is least
vulnerable area of the body
Possibility of solid or liquid
toxicants being ingested is very
limited
Local Effects
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Confined to specific area of
body where contact with the
toxic material occurs
For example, a sensitiser may
cause a specific allergic
reaction on contact with the
skin or respiratory tract
Systemic Effects
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Occur at organs/parts of the
body distant from the site
where initial contact with the
toxic substance was made
Common target organs include
lungs, liver, nervous system,
bone marrow, kidneys and skin
Defence Mechanisms of
the Body
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Respiratory Defence
Lachrymation
Immune Response
Inflammatory Response
Fibrotic Response
Respiratory Defence
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Moist hairs in the nose trap large particles
Other particles are sneezed or coughed
out
Very tiny particles are breathed in and
back out again
Solid deposits in the lower respiratory
airway are moved up the ciliary escalator
0.5 - 7 microns is the respirable range
Respiratory Protection
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Phagocytosis
• Amoeba like cells which engulf
particles of dust and remove them
• Can cause formation of elastic
scar tissue on lungs for certain
dusts, which leads to reduced lung
function
Lachrymation
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Eye is protected from injury by bony structure
which houses it
Eyebrows divert liquids to outer side
Eyelashes prevent particles from entering
eyes and cause lids to close rapidly if touched
Exposed surface of eye is continuously
moistened by tears (lachrymation) - any
irritation of the eye causes an immediate
increase in secretion and the irritation is
diluted or washed away
Immune Response
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Rash occurs on skin in response
to contact with certain
substances
Once sensitisation occurs,
further exposure to the
substance even at low
concentrations will cause
inflammation
Inflammatory Response
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The reaction of tissue to a
harmful agent which is
insufficient to kill the tissue
A defensive process, but can
result in disease if called upon
to act for too long
Collagen is formed to repair
damaged tissue