Why is Asbestos a Problem? Linda Apthorpe

Transcription

1 Why is Asbestos a Problem? Linda Apthorpe 1

2 Session Contents What is Asbestos? History of Use Asbestos containing materials (ACM) Friable Non friable Health Effects 2

3 What is Asbestos? Group of naturally occurring minerals -> fibrous silicates Long & thin structures Defined by length to width, i.e. aspect ratio Two families of minerals: Fibrous Serpentine Chrysotile Fibrous Amphiboles Amosite Crocidolite Anthophyllite Tremolite Actinolite 3

4 History of Use Greek origins, Asbestos unquenchable or inextinguishable Used since BC: wicks, paper, funeral shrouds Used (extensively) industrial since mid 19 th C Use of the wonder fibre multiplied by end of 19 th C Industrial Revolution 4

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6 Asbestos: Regulated vs Commercial All 6 forms are prohibited in Australia (new use/re-use, import/export) Only 3 forms typically used in commercial products Chrysotile white asbestos, strong, curly, flexible fibres Amosite brown asbestos, heat resistant, brittle fibres Crocidolite blue asbestos, alkalis resistant, flexible, strong fibres Chrysotile Amosite Crocidolite Source: L. Apthorpe 6

7 Asbestos Containing Materials - ACM Friable - crushed to powder between fingers when dry e.g. insulation type products, hot water pipe lagging, millboard, sprayed limpet Non Friable all other ACM (incl. bonded where fibres are locked into a matrix) e.g. asbestos cement, flat & corrugated pieces, asbestos cement pipes, vinyl tiles, electrical mounting boards Note: Definitions from the Code of Practice, Control 7

8 Friable: Asbestos Insulation Non Friable: Asbestos Cement Source: L. Apthorpe 8

9 Friable Examples 9

10 Non Friable Examples 10

11 Asbestos and Risk to Health Hazard potential to cause damage Risk likelihood to cause damage Asbestos is a hazard, however asbestos may not pose a risk A risk assessment for asbestos depends on three things: route of entry (asbestos is an inhalation hazard only) level of exposure (high airborne fibre concentrations) duration of exposure (many years of high fibre concentrations) 11

12 Remember! People exposed to high airborne fibre concentrations over many years of working life may be at risk of an asbestos related disease 12

13 Respirable Fibres Fibres greater than 5 um in length and not exceeding 3 mm in width, with a length to width ratio of greater than 3:1 13

14 Health Effects Asbestos fibres are a problem because: Of their size (respirable fibres) They have ability to split into finer fibres They are resistant to chemical attack Development of disease relies on the 3 D s: Dose Durability (bioavailability) Dimensions (respirable fibres) 14

15 Asbestos Diseases The effects of asbestos fibre inhalation may include: Pleural Plaques Calcified, benign, significant exposure, latency 20+ Asbestosis Scarring/fibrosis, dose response, onset years Lung Cancer Malignant, synergistic FX smoking, onset years Mesothelioma Malignant, amphibole & non asbestos exposure, latency up to 50 years 15

16 Asbestos Exposure Asbestos is a known human carcinogen Background concentrations Community expectation -> nobody is exposed to any asbestos Australian Exposure Standard: TWA 0.1 f/ml 16

17 Asbestos Exposure During ACM disturbance activities ACM removals: Friable high risk profile Non Friable low risk profile Even with slight disturbances, friable ACM has significantly more chance of liberating fibres than non friable ACM Friable Non Friable 17

18 Airborne respirable fibres = Potential risk to health All ACM in good condition, left in situ and undisturbed poses no risk to health Classically friable ACM - the likelihood of free or respirable fibres is possible even with slight disturbance Burnt AC, can be deemed friable for removal purposes only, however it is usually still in bonded form and unlikely to cause airborne respirable fibres, even with disturbance More on ACM removals in next session! 18

19 Resources Federal & State Legislation (WHS 2011) Safework NSW docs & info (building materials, soils, licencing etc.) SafeWork NSW Codes of Practice Management & Control Removal AIOH Position Paper 19