1

Prepared by:

Penny DigbyPrincipal Adviser (Occupational Health)

Workplace Health and Safety Queensland

Asbestos

typeshistoryrespiratory system and defence mechanismsasbestos related diseases risk of developing an asbestos related disease

Part 1. Overview

naturally occurring mineralscrystallisedlong thin fibresfibre bundlescrocidolite (blue)amosite (brown or grey)amphibole groupchrysotile (white)serpentine group

What is asbestos?

2

Blue – crocidolitenot as commonly foundstraight, stifferneedle-like fibresstrongesthigh resistance to acidsyarn and rope lagging thermal insulation high bulk volume

Different types of asbestos -Amphiboles

Blue – crocidolitesprayed insulation similar widespread usetendencymixturesother varieties

Different types continued

Brown or grey – amositeharsh spiky fibresgood tensile strengthresistance to heatcoarser naturerigid productsinsulation boards

Different types of asbestos-Amphiboles

3

White – chrysotilemost flexiblefiercest heatsoft and flexiblespun and wovenmost abundant formproduction and usage –93%

Different types of asbestos -Serpentine

White – chrysotilewide variety of productsyarn, rope and textilescement, insulation boards, friction materials and thermo-plastics

Different types of asbestos -continued

Inextinguishable

Finnish peasants potterylog huts

Greekswicks

History of asbestos

4

Romanswove into fabricstowels, nets and head coveringsashes

declinedMiddle Ages1700sintensifiedIndustrial Revolution19th century

History of asbestos

1950s highest user per capita in the worldbulk of asbestos used 20th century (>90%) produce asbestos cement1945 – 1954 70,000 NSW – 57%using AC cladding

History of asbestos

until 1960s25%bulk of asbestos fibre used - Chrysotileaddition of amphibolesamositecrocidolite

History of asbestos continued

5

mined in Australia – 100 yearsWittenoom 1943-1966mesothelioma 1962world usage now four product categories

AC, friction materials, roof coatings, gaskets

History of asbestos

industrially peaked 1970smost of fibre 20th centuryexception of the 1980simported

great strengthresistance to heat, firechemicals and corrosionover 3,000

History of asbestos

31 December 2003all products containing asbestosbanned Australia-wideimported, stored, supplied, sold, installed, used or re-used

removal of asbestos products in situ when prohibition took placewhen replaced – non-asbestos alternatives

a) analysis, research or samplingb) maintenancec) removal or disposald) encapsulation or enclosure

Asbestos ban

6

7

8

Respiratory system

Respiratory system

9

since gas exchanges other organspassagewaysair to reach the lungsfilter air asbestos fibresinhaled asbestos fibresbypassbody’s filtering mechanismalveoli

Respiratory system

layer of sticky mucous

traps fibres

removed

cilia

larger fibres

expelled or swallowed

smaller fibres

alveoli

How does the body filter the air that reaches the lung?

What happens to the asbestos fibres within the alveoli?

10

Pleural plaques

Asbestosis

Lung cancer

Mesothelioma

Asbestos related diseases

fibrous thickeningmembranes lining the lungmost common manifestationmore sensitive low intermittent exposurenot a cancernot cancer causing20 years to developno symptomsno treatment

Pleural plaques

not a cancerirreversible fibrosisaccumulation of asbestos fibres15-20 yearscontinued exposure high respirable fibre concentrations associated with highest fibre burdensrespiratory impairmentlung cancer heart failure

Asbestosis

11

asbestos causes lung cancernot distinguishable from those cancerscaused by other agents – tobacco smokesigns and symptomslatency typically 10-40 yrs occur only following levels of exposureassociated with asbestosis

Lung cancer

courts require evidence of asbestosisexposure to asbestossufficient to cause asbestosisbefore attributing lung cancer to asbestosrisk increased greatly by smoking

Lung cancer

cancerchest cavity - abdominal cavitystrongly associated with asbestos exposureblue asbestosnot appear to be dose-relatedlow asbestos exposure87% occupational exposuresmoking no influence latency period 20-60 yrslife expectancy ~ 8 months

Mesothelioma

12

incidence increasing since 1965extensive use and productionprevious decades

Mesothelioma

Mesotheliomafrom 1986 onwardstrend of increasing incidence restricted to aged groups over 50occupational exposure controls 1970sWA highest incidence rates

1. Fibre type – (greater with amphiboles)2. Size and shape of fibres (long fibre more

hazardous)3. Concentration of asbestos fibres in the

inhaled air4. Period of time over which the person was

exposed

What is the risk of developing an asbestos related disease?

13

blue asbestossignificantly more hazardousstraight, stiffer, very needle-likethe smaller airwayssofter wavier white

What is the risk of developing an asbestos related disease? Fibre type

relative potency of fibres - mesotheliomablue : brown : white = 500 : 100 : 1

relative potency of fibres - lung cancerblue : brown : white = 10-50 : 10-50 : 1

blue - elimination rate from lung= 10-15% per year and white > blue

What is the risk of developing an asbestos related disease? Fibre type

Inhaling longer more durable fibres –amphibolecontributes to severity of asbestos disorderschrysotile used most widely< 5 µm long mostly removed> 5 µm long deposited – may cause diseasemost hazardous fibres:> 8µm long, <0.5 µm diameter

A human hair is approximately 20 to 100 µm wide

What is the risk of developing an asbestos related disease? Size and shape of fibres

14

short-term exposure tohigh concentrationslong term exposure to low concentrations of asbestos fibresasbestos related diseasediseases that are occurring nowpast exposuresasbestos used extensivelyinadequate control over workers’ exposure

What is the risk of developing an asbestos related disease? Concentration of fibres in the inhaled air

600 fibre/mL of air – baggers at Wittenoom150 fibre/mL of air – asbestos pulverisers and disintegrators – AC industry0.1 fibre/mL of air – current exposure standard

What is the risk of developing an asbestos related disease? Concentration of fibres in the inhaled air

15

Period Fibres/ml Notes

Before 1930 >> 100 Mining, milling, manufacture and insulation installation

1935 – 1945 >100

1950’s 100

1960 – 1971 20 Most of today’s cases come mainly from these exposures.

Effects of reduced exposure standards, increased regulation and shift to tradesman exposures

1975 5

1980 1

2000+ <0.1 1,000 times reduction over 100 years of use

Historical exposure levels(Note: Environmental Background = 0.0005 fibres/ml)

16

Concentration of fibres for particular tasks

Situation Level (fibres/ml) NotesCutting AC cementAngle grinderOutdoor jobs

Peak = 50TWA = 1.0-2.0

Average 10-20 minutes cutting per day

Indoor jobs TWA = 6.4 Restricted ventilation

Concentration of fibres for particular tasks

Cleaning AC Roofing Vertical claddingDry brushing (wire) 3 f/ml 5-8 f/mlWet brushing (wire) 1-3 f/ml 1-2 f/ml

Also, removal and stacking of a/c sheeting…up to 0.5 f/ml

Typical environmental background

0.0005 fibres/ml(background incidence rate - much less than 1 per 1,000,000

per year)

~ 5000 fibresbreathed/day

Occupational exposure standard (8 hr)

0.1 fibres/ml ~ 135,000 fibresbreathed/day

A proportion of breathed fibres are eliminated or rendered innocuous

Note: different analytical methods used for Env vs Occ

Environmental vs occupational levels - fibres breathed per day

17

30 years as carpenter, cutting and fitting a/c sheeting40 years as a heavy smoker5-10 years of moderate exposure (construction)RRLC = 2.0Cumulative exposure assessed as 1/10 of that required RRLC = 2.0

Case study:Judd vs Amaca P/L, July 2003

Mr Judd’s RRLC from smoking = 20 times the RRLC for non smokersRuling: probability of LC from asbestos exposure alone was very low cf., risk from his smoking Judgement went against Mr Judd

Case study: Judd vs Amaca P/L, July 2003

Wittenoom mine or mill 16.6

Power station worker 11.8

Railway labourer 6.4

Navy/merchant navy 5.1

Wittenoom town 3.1

Carpenter/joiner 2.4

Waterside worker 2.1

Plasterer 2.0

Boiler maker/welder 1.9

Bricklayer 1.8

Plumber 1.7

Painter/decorator 1.2

Electrical fitter/mechanic/electrician

0.7

Vehicle mechanic 0.7

All Aust. men 0.39

All Aust. women 0.05

Lifetime risks mesothelioma (1986-2000) occupational groups exposed 30-50 years previously

18

occupational groupsminingmillingshipbuildingpower industries railway carriage construction

What is the risk of developing an asbestos related disease? Period of time over which a person was exposed

office and industrial building constructionAC productionwere at the greatest risk of exposure

The risk of developing an asbestos related disease continued

because asbestos materials and products used extensively in buildings and homesstill potentialhome renovators building and maintenance workers exposed

What is the risk of developing an asbestos related disease? Period of time over which a person was exposed

19

Low risk of asbestosis (requires large exposures)Lung cancer risk is low for a/c sheeting work, but greatly exacerbated by smoking Mesothelioma requires only small exposures, but risk is low for work with a/c sheeting if appropriate controls are implementedRisk is dependent on duration of exposure, fibre concentration, fibre type, fibre length etc.

What are risks from A/C products?

Nevertheless asbestos is a human carcinogenConsequently we must take reasonable precautions and follow the Asbestos Removal Code and Asbestos Management Code

Risks from A/C products continued