Asbestos. Part 1. Overview. What is asbestos? Prepared by: Penny Digby Principal Adviser (Occupational Health) Workplace Health and Safety Queensland

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1 Asbestos Prepared by: Penny Digby Principal Adviser (Occupational Health) Workplace Health and Safety Queensland Part 1. Overview types history respiratory system and defence mechanisms asbestos related diseases risk of developing an asbestos related disease What is asbestos? naturally occurring minerals crystallised long thin fibres fibre bundles crocidolite (blue) amosite (brown or grey) amphibole group chrysotile (white) serpentine group 1

2 Different types of asbestos - Amphiboles Blue crocidolite not as commonly found straight, stiffer needle-like fibres strongest high resistance to acids yarn and rope lagging thermal insulation high bulk volume Different types continued Blue crocidolite sprayed insulation similar widespread use tendency mixtures other varieties Different types of asbestos- Amphiboles Brown or grey amosite harsh spiky fibres good tensile strength resistance to heat coarser nature rigid products insulation boards 2

3 Different types of asbestos - Serpentine White chrysotile most flexible fiercest heat soft and flexible spun and woven most abundant form production and usage 93% Different types of asbestos - continued White chrysotile wide variety of products yarn, rope and textiles cement, insulation boards, friction materials and thermoplastics History of asbestos Inextinguishable Finnish peasants pottery log huts Greeks wicks 3

4 History of asbestos Romans wove into fabrics towels, nets and head coverings ashes declined Middle Ages 1700s intensified Industrial Revolution 19 th century History of asbestos 1950s highest user per capita in the world bulk of asbestos used 20 th century (>90%) produce asbestos cement ,000 NSW 57% using AC cladding History of asbestos continued until 1960s 25% bulk of asbestos fibre used - Chrysotile addition of amphiboles amosite crocidolite 4

5 History of asbestos mined in Australia 100 years Wittenoom mesothelioma 1962 world usage now four product categories AC, friction materials, roof coatings, gaskets History of asbestos industrially peaked 1970s most of fibre 20 th century exception of the 1980s imported great strength resistance to heat, fire chemicals and corrosion over 3,000 Asbestos ban 31 December 2003 all products containing asbestos banned Australia-wide imported, stored, supplied, sold, installed, used or re-used removal of asbestos products in situ when prohibition took place when replaced non-asbestos alternatives a) analysis, research or sampling b) maintenance c) removal or disposal d) encapsulation or enclosure 5

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8 Respiratory system Respiratory system 8

9 Respiratory system since gas exchanges other organs passageways air to reach the lungs filter air asbestos fibres inhaled asbestos fibres bypass body s filtering mechanism alveoli How does the body filter the air that reaches the lung? layer of sticky mucous traps fibres removed cilia larger fibres expelled or swallowed smaller fibres alveoli What happens to the asbestos fibres within the alveoli? 9

10 Asbestos related diseases Pleural plaques Asbestosis Lung cancer Mesothelioma Pleural plaques fibrous thickening membranes lining the lung most common manifestation more sensitive low intermittent exposure not a cancer not cancer causing 20 years to develop no symptoms no treatment Asbestosis not a cancer irreversible fibrosis accumulation of asbestos fibres years continued exposure high respirable fibre concentrations associated with highest fibre burdens respiratory impairment lung cancer heart failure 10

11 Lung cancer asbestos causes lung cancer not distinguishable from those cancers caused by other agents tobacco smoke signs and symptoms latency typically yrs occur only following levels of exposure associated with asbestosis Lung cancer courts require evidence of asbestosis exposure to asbestos sufficient to cause asbestosis before attributing lung cancer to asbestos risk increased greatly by smoking Mesothelioma cancer chest cavity - abdominal cavity strongly associated with asbestos exposure blue asbestos not appear to be dose-related low asbestos exposure 87% occupational exposure smoking no influence latency period yrs life expectancy ~ 8 months 11

12 Mesothelioma incidence increasing since 1965 extensive use and production previous decades Mesothelioma from 1986 onwards trend of increasing incidence restricted to aged groups over 50 occupational exposure controls 1970s WA highest incidence rates What is the risk of developing an asbestos related disease? 1. Fibre type (greater with amphiboles) 2. Size and shape of fibres (long fibre more hazardous) 3. Concentration of asbestos fibres in the inhaled air 4. Period of time over which the person was exposed 12

13 What is the risk of developing an asbestos related disease? Fibre type blue asbestos significantly more hazardous straight, stiffer, very needle-like the smaller airways softer wavier white What is the risk of developing an asbestos related disease? Fibre type relative potency of fibres - mesothelioma blue : brown : white = 500 : 100 : 1 relative potency of fibres - lung cancer blue : brown : white = : : 1 blue - elimination rate from lung = 10-15% per year and white > blue What is the risk of developing an asbestos related disease? Size and shape of fibres Inhaling longer more durable fibres amphibole contributes to severity of asbestos disorders chrysotile used most widely < 5 µm long mostly removed > 5 µm long deposited may cause disease most hazardous fibres: > 8µm long, <0.5 µm diameter A human hair is approximately 20 to 100 µm wide 13

14 What is the risk of developing an asbestos related disease? Concentration of fibres in the inhaled air short-term exposure to high concentrations long term exposure to low concentrations of asbestos fibres asbestos related disease diseases that are occurring now past exposures asbestos used extensively inadequate 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 Wittenoom 150 fibre/ml of air asbestos pulverisers and disintegrators AC industry 0.1 fibre/ml of air current exposure standard 14

15 Historical exposure levels (Note: Environmental Background = fibres/ml) Period Fibres/ml Notes Before 1930 >> 100 Mining, milling, manufacture and insulation installation > s Most of today s cases come mainly from these exposures. Effects of reduced exposure standards, increased regulation and shift to tradesman exposures <0.1 1,000 times reduction over 100 years of use 15

16 Concentration of fibres for particular tasks Situation Level (fibres/ml) Notes Cutting AC cement Angle grinder Outdoor jobs Peak = 50 TWA = Average minutes cutting per day Indoor jobs TWA = 6.4 Restricted ventilation Concentration of fibres for particular tasks Cleaning AC Roofing Vertical cladding Dry brushing (wire) 3 f/ml 5-8 f/ml Wet brushing (wire) 1-3 f/ml 1-2 f/ml Also, removal and stacking of a/c sheeting up to 0.5 f/ml Environmental vs occupational levels - fibres breathed per day Typical environmental background Occupational exposure standard (8 hr) fibres/ml (background incidence rate - much less than 1 per 1,000,000 per year) ~ 5000 fibres breathed/day 0.1 fibres/ml ~ 135,000 fibres breathed/day A proportion of breathed fibres are eliminated or rendered innocuous Note: different analytical methods used for Env vs Occ 16

17 Case study:judd vs Amaca P/L, July years as carpenter, cutting and fitting a/c sheeting 40 years as a heavy smoker 5-10 years of moderate exposure (construction) RR LC = 2.0 Cumulative exposure assessed as 1/10 of that required RR LC = 2.0 Case study: Judd vs Amaca P/L, July 2003 Mr Judd s RR LC from smoking = 20 times the RR LC for non smokers Ruling: probability of LC from asbestos exposure alone was very low cf., risk from his smoking Judgement went against Mr Judd Lifetime risks mesothelioma ( ) occupational groups exposed years previously 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/ 0.7 electrician Vehicle mechanic 0.7 All Aust. men 0.39 All Aust. women

18 What is the risk of developing an asbestos related disease? Period of time over which a person was exposed occupational groups mining milling shipbuilding power industries railway carriage construction The risk of developing an asbestos related disease continued office and industrial building construction AC production were at the greatest risk of exposure What is the risk of developing an asbestos related disease? Period of time over which a person was exposed because asbestos materials and products used extensively in buildings and homes still potential home renovators building and maintenance workers exposed 18

19 What are risks from A/C products? 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 implemented Risk is dependent on duration of exposure, fibre concentration, fibre type, fibre length etc. Risks from A/C products continued Nevertheless asbestos is a human carcinogen Consequently we must take reasonable precautions and follow the Asbestos Removal Code and Asbestos Management Code 19