Asbestos
Dr Jim Lister
Environment Group Manager
Glasgow Scientific Services
Asbestos
• Asbestos is the generic name for six
naturally occurring minerals
• Physical properties
Strength
Flexibility
Insulating Properties
Resistance to heat and Chemicals
Low electrical conductivity
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Types of asbestos
•
•
•
•
Chrysotile (white) White curly fibres
Amosite (brown) Straight sharp fibres
Crocidolite (blue) Straight fibres
Other Types Anthophyllite, Tremolite and
Actinolite
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Asbestos - The Hazard
 Asbestos is the single biggest cause of work
related deaths in the UK. - HSE
 3000 Deaths per year associated with Asbestos
- due to past exposure
 Airborne Hazard – Fibres are produced when
asbestos containing materials are disturbed
 Respirable fibres – enter lung – cause fatal
disease
 Materials that remain undisturbed – no risk to
health
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Risk Factors
• Asbestos related diseases are caused by
the inhalation of Asbestos fibres.
• Fibres have to be respirable.
Specific dimensions
• Risk Factors CONCENTRATION +
DURATION = DOSE
• Some evidence that Asbestos diseases
follow a dose response relationship.
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Latency Period For Asbestos
Disease
• Time taken from first exposure to
discovery of illness.
• Shortest latency period is 5-10 years
• It can often take up to 40 years or more
• No safe level of exposure
• Secondary Exposure
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Asbestos diseases
• Fibres that are not cleared from the lungs and
remain trapped in the body can cause a range of
diseases.
• Asbestos lung cancer- fibres remaining trapped
in the lung –severe respiratory damage High
Asbestos concentrations
• Mesothelioma- translocation of fibres to the
pleura causing malignant disease in the thin
membranes lining the chest. - Lower Asbestos
concentrations
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Identification of Asbestos - Principle
• Survey area-collect representative
samples of all suspect materials.
• Visual Examination of Bulk Material
• Removal of sub-samples ( usually fibrous
material ) from the bulk material
• Mounting sub-sample on slide and
clearing with acid or solvent.
• Microscopal examination using plane and
polarised light.
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Identification of Asbestos - Equipment
• Glass Jars or polythene bags for collection of
samples
• Disposable gloves
• Tweezers/pliers
• Wash bottle (water)
• Microscope slides and cover slips
• Tissues
• Hydrochloric acid, solvent
• Polarising microscope
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Identification of Asbestos
• Assess and survey the area and secure a
representative sample.
• Place sample jar/ bag in fume cupboard
• Sort through sample with tweezers –
transfer any fibrous material to slide
(ensure representative sample is taken,
sample all fibres)
• Clear filler material
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Identification of Asbestos
• Examine the slide microscopically – scanning
the entire slide – using plane light and polarising
any suspicious fibres.
• Clean-up
– Return Slides to glass Jar/ bag.
– Clean the fume cupboard surfaces – vacuum
cleaner fitted with suitable filter, wet wipes.
– Place all material in labelled “asbestos” bag
for special disposal.
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Example of ACM Board material
10-30% Amosite / Chrysotile
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Example of ACM - Insulation
Pipe insulation
10-30% Chrysotile/Amosite/Crocidolite
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Example of ACM - Painted board
10-30% Amosite / Chrysotile
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Example of ACM - Asbestos rope
100% Chrysotile
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Example of ACM - Floor tiles
Vinyl floor tiles 5-7% Chrysotile
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Example of ACM - Toilet Cistern
Toilet Cistern
5-10% Chrysotile/Amosite
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Example of ACM - Corrugated Roofing
Roofing / Cladding materials
10-30% Chrysotile/Amosite
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Example of ACM - Sprayed Insulation
Sprayed Insulation –
100% Amosite/Crocidolite
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Chrysotile Asbestos
Teased out fibres
Fine Wispy
Fibres
Knee bend
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Chrysotile Asbestos
Fibres glow bright white on polarisation.
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Amosite Asbestos
Bundles of sharp
tightly packed fibres
Straight rigid fibres
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Amosite Asbestos
Polychromatic “rainbow” effect on polarisation
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Crocidolite Asbestos
Fibres not as rigid as Amosite
Fibres
Dark inky
Blue
Wispy fibres
present where
the fibre bundles
are teased out
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Crocidolite Asbestos
Fibre bundles exhibit a red/brown appearance on polarisation
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Cotton Fibres
Ragged
fibre
ends
Distinct
Cellular
structure
Fibres
twisted
and bent
Often - Polychromatic effect without polarisation
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Cotton fibres
Polychromatic effect within cellular structure not along fibre
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Hemp
Ragged fibre ends
Cellular structure
Polychromatic effect present with or without polarisation
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Hemp
Ragged
fibre ends
Polychromatic effect present with or without polarisation
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Jute
Distinct cellular structure, ragged fibre ends, polychromatic effect.
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Glass fibre
Transparent
Fibre
Ends
truncated
Variable
diameter
No effect on polarisation
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Polymeric fibre (polyester)
Single
filament
Fibre ends
blunt
Regular
diameter
Bending or
curvature
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Polymeric fibre (polyester)
Polychromatic effect
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