1. Asbestos: health effects and risk
Peter Franklin
Senior Scientific Officer
Environmental Health Directorate

2. What is asbestos
Naturally occurring mineral that has crystallised to form long thin fibres and fibre bundles (silicate fibres)
Two main types (6 specific materials)
Amphibole – crocidolite (blue asbestos)
amosite (brown)
(tremolite, actinolite, anthophylite)
Serpentine – chrysotile (white)
Used extensively because of its flexibility, tensile strength, insulation from heat and electricity, and chemical inertness

3. Why does it cause disease?
Disease is caused by the inhalation of asbestos fibres
Fibre shape and size
Thin fibres that can penetration deep into the lung
Persistence in the lungs
Cant be broken down
Difficult to clear from the lungs

4. Asbestos-related Diseases (ARD)
Diseases caused by asbestos exposure
Malignant (cancers)
Mesothelioma
Lung cancer
Other cancers (laryngeal, colo-rectal, ovarian)
Non-malignant
Asbestosis
Diffuse pleural thickening
Pleural plaques

5. Dose-response for asbestos exposure and disease
Disease risk
Most ARD have been due to occupational exposure BUT is now as much a public as occupational health concern
Risk of disease increases with level of exposure
For mesothelioma (and other cancers?) there is no known ‘safe’ threshold
For other ARD (eg asbestosis) high levels of exposure are required (but a lot of uncertainty)
Dose-response for asbestos exposure and disease
Mesothelioma rate
(per 100,000)
Cumulative exposure (f/ml-yrs)

6. Non-occupational exposure scenarios
Around the home
Weathered/Broken asbestos containing material (ACM)
DIY Renovations
Pressure Cleaning
In the community (built environment)
Dumping
Contaminated Land
Fire damage buildings
Dodgy Demolitions
Other concerns
C&D Recycling
Mining Activities

7. Mesothelioma and non-occupational exposure
Mesothelioma is a specific outcome of asbestos exposure
There is no other known cause of mesothelioma
WA Mesothelioma Registry
Includes all mesotheliomas in WA (1960 – present)
Assigns a primary route of exposure based on occupational and non-occupational history

8. Mesothelioma cases in WA: 1960 - 2014
Exposure route
Number of cases
Proportion of all cases
Occupational (1556)
Wittenoom workers
292
13.4
Other workers
1264
58.1
Non-occupational (310)
Wittenoom residents 81
3.7
Wittenoom visitors 22
1.0
Home renovation (DIY)
153
7.0
Family member of worker 32
1.5
Other
Unknown
309
14.2
Total
2124
100
* Still ~ 100 new cases per year

9. DIY and Mesothelioma 153 cases since 1981, BUT
Occupational
DIY
153 cases since 1981, BUT
152 cases were exposed before asbestos was banned
Most recent exposure was in 1991
More renovations (↑ risk)
Greater precaution (↓ risk)

10. Non-occupational fibre levels
Background levels
< f/mL (workplace standard 0.1 f/mL over 8hrs)
Near weathering ACM
– f/mL (decreases with distance from ACM)
In buildings
(ACM in good condition)
(with damaged ACM)
Renovation activities
Hand sawing ACM sheet 1 – 4 f/mL
Jigsaw – 10
Circular saw 10 – 20
Sanding vinyl tiles ~1
Removing pipe insulation – 6
ACM removal ~1.5

11. Risk of developing Mesothelioma
Very rare cancer
Background rate: 1-2/1,000,000/yr
Background rate possibly due to either background or unknown exposures
Risk from (unprotected?) home renovation
Hard to determine - no idea of number of people exposed
(Very crude) estimate: 5-10X above background
Still very low (Witt miners ~2000/1,000,000pyr)
DIY exposures likely to be much > than other non-occupational exposures ( risk from other exposures is much lower)

12. Asbestos needs to be managed with extreme caution
Concluding remarks
Risk of ARD from non-occupational exposures is very low
Just because you are exposed to asbestos DOES NOT mean you will get an ARD
BUT
there is no known safe threshold level of exposure
the consequences are very high
there is no way of determining who will develop an ARD
Asbestos needs to be managed with extreme caution