SILICA SEMINAR Linda Apthorpe & Ian Firth www.aioh.org.au AIOH - PDF document

SILICA SEMINAR Linda Apthorpe & Ian Firth www.aioh.org.au AIOH Seminars AIOH runs technical seminars throughout the year • Purpose: •  Encourage professional development for members and others working in the industry  Find out about latest industry trends in health and safety  Determine what you can do to achieve effective positive behaviour change in your workplace  Hear what others are doing by networking with peers with similar interests 2 Presenters Ian Firth • IC Firth OHs Solutions PTY LTD Linda Apthorpe • 3 1

Your Turn! Please introduce yourself and tell us why you are here! • 4 Crystalline Silica Present in many workplaces • • Recent publicity -> engineered stone industry SafeWork Australia • State Jurisdictions • 5 Topics RCS Occurrence and Types • RCS Health effects • RCS Exposure Standards • • Exposure Risk and Disease Incidence Sampling & Analytical Methods • Control • The future for RCS • 6 2

SILICA SEMINAR RCS - Introduction www.aioh.org.au Session Outcomes Describe different forms of silicon dioxide • • Discriminate between types/phases of quartz List workplaces where crystalline silica can be found • 8 RCS Occurrence and Types 9 3

Silica SiO 2 Crystalline Amorphous 10 Silicon Dioxide – Quartz SiO 2 – oxide of silicon • • Most abundant mineral on earth Commonly found: sand, rocks & • diatoms • Hard abrasive mineral Also present in soils & clays • 11 Quartz Properties Quartz is slightly soluble in body fluids and soluble in HCl • It is insoluble in water, organic solvents, most mineral • acids. Molecular weight: 60.09 • • Specific density: 2.65 • Melting point: 1,600 deg C Boiling point: 1,723 deg C • 12 4

Used for… 13 Crystalline Types Quartz • Source: touch of modern Cristobalite & Tridymite (high temperature) • 14 Crystalline Types Coesite & Stishovite (dense, meteorites) • Source: individual.utoronto.ca Source: Britannica.com Free silica • 15 5

Phase Diagram 16 Other Types of Silica Microcrystalline silica (opal, flint, tripoli, silica flour, • chalcedony) Source: via Google 17 Other Types of Silica Amorphous silica • 18 6

Other Types of Silica Fumed Silica • Source: Wikimedia commons • Lechatelierite, rare amorphous glass 19 Other Types of Silica Silica fume (microsilica) • Average diameter: 150 mm 20 Terminology Terms for the same thing? •  Respirable crystalline silica (RCS)  Respirable crystalline quartz  Respirable silica  Respirable quartz  Respirable alpha quartz  Crystalline quartz  Crystalline silica 21 7

Workplace Silica Crystalline Silica SiO 2 α -Quartz Cristobalite Tridymite 22 Quartz in Workplaces What types of workplaces would RCS be found? • • Mining, rock-drilling, sandblasting, construction, foundry work, stonecutting, drilling, quarrying (hard rock & sand), building and general construction work, road work and road construction, cement products manufacturing, demolition operations, sweeping, masonry, tunnelling, ceramics & brick manufacture, demolition, abrasive blasting, agricultural earth works, asphalt production, abrasives, glass & paint manufacture... 23 24 8

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% Quartz Type ~% Quartz Granite 25-50 Shale 22 Natural quartzite 65-90 Natural sandstone 65-90 Engineered stone Up to 90 (+ cristobalite) Natural Sand 80-90 Manufactured Sand 0-90 Concrete (as sand/quartz) 20-25 Concrete 20-60 (as SiO 2 ) 34 Exposure Sources Exposure to RCS is widespread across Australia • (mainly from mining & construction industries) Cristobalite & Tridymite •  formed in high temperatures Remember to consider possibility of presence of • cristobalite (& tridymite) in workplaces 35 Session Recap Different forms of silicon dioxide •  crystalline & amorphous • Discrimination between types/phases of quartz  quartz, cristobalite, tridymite Workplaces where crystalline silica can be found • 36 12

References ACGIH Documentation of the Threshold Limit Values & • Biological Exposure Indices, 7 th Edition Pattys Industrial Hygiene & Toxicology, 3 rd (rev) edition • ILO Encyclopaedia of Occupational Health & Safety, 3 rd (rev) • edition IARC monographs (No 68-6) • OSHA website (www.osha.gov) • NIOSH website (www.cdc.gov/NIOSH) • SafeWork Australia (www.safework.gov.au) • 37 SILICA SEMINAR RCS – Health Effects www.aioh.org.au Session Outcomes Describe the health effects of RCS • Specify the elements of a health surveillance program • Explain the factors that affect the disease potential of • RCS 39 13

Health Effects of RCS Silicosis • Bronchogenic carcinoma • COPD • Pulmonary tuberculosis • Industrial bronchitis • Auto-immune diseases • • Renal disease 40 The Respiratory Tract 41 Gas Exchange Region of the Lung 42 14

Defence Mechanisms The respiratory system has a number of ‘dust filters’ that must be passed before dust can reach a point in the lung where it can cause damage. Clearance of dust is by:  Hairs in the nose  Transport via the mucociliary ladder  Removal by scavenger cells (macrophages) in the alveolar region Health effects can eventuate when these mechanisms become overloaded. 43 Defence Mechanisms Damaged cilia Healthy cilia 44 Defence Mechanisms Macrophage Action in Alveolar Region Julie A. Champion and Samir Mitragotri, Role of target geometry in phagocytosis , Proc Natl Acad Sci U S A. 2006 March 28; 103(13): 4930 – 4934. 45 15

Lung Function Testing - Spirometry Graphs 2 ways of looking at a Spirometry result FLOW VOLUME VOLUME TIME 46 Shapes of Spirometry Curves Abnormal Ventilatory Function Normal (?) Obstruction Restriction Mixed Flow Flow Flow Volume Volume Volume From: DP Johns, R Pierce. Pocket Book of Spirometry . Sydney: McGraw-Hill, 2003. 47 Lung disease - Obstructive symptom (COPD) Asthma, Bronchitis, Emphysema  Increased resistance of airways  Narrowing of the airways from brochospasm  Swollen tissues  Excessive mucous  Increased thickness of airway wall (collagen) due to remodelling  Loss of elastic recoil (due to alveoli collapse - emphysema) 48 16

Lung disease - Restrictive symptom Diffuse Lung Diseases  decreased respiratory muscle strength  stiff lungs (increased elastic recoil – fibrosis)  shrunken and non-homogeneous lung without obstruction of larger airways  total lung volume reduced (forced vital capacity, FVC)  the ratio of FEV 1 /FVC is normal (forced exhaled volume in 1 second, FEV 1 ) 49 Interpretation Algorithm Is FEV 1 /FVC No less than 70% Is FVC below lower limit of normal? Yes Yes No Obstruction Severity: Use % predicted FEV 1 Restriction Normal Referral for Spirometry confirmation & diagnosis 50 51 17

Grinders disease Silicosis among the grinders of razors, forks, knives, saws and other edge tools in Sheffield, England THE ILLUSTRATED LONDON NEWS, January/March, 1866 52 Potter’s Rot - 1840 The "scourers", chiefly young women, necessarily inhale, the room being literally filled with dust, the fine particles of flint, which produce similar effects to what is provincially denominated, in the Sheffield trade, " the grinder's rot; " something might be done, perhaps, to lessen this evil, if judicious precautionary measures were adopted. I have suggested the use of a wet sponge, so adapted to the mouth and nostrils that the air of respiration must necessarily pass through it…... " http://www.thepotteries.org/jobs/scourer.htm 53 Pneumonoultramicroscopicsilicovolcanoconiosis Name given to silicosis when caused by the specific • exposure to fine silica dust found in volcanoes Longest word in the English language (45 letters) • 54 18

Notice chalked up in a foundry in Coventry (1934) 55 Silicosis • Progressive fibrotic lung disease (pneumoconiosis) • Frequently not the primary cause of death • Classification is made according to the disease's severity, onset and rapidity of progression:  chronic silicosis (includes simple and complicated silicosis)  accelerated silicosis  acute silicosis 56 Silicosis Symptoms: Shortness of • breath Cough • • Rapid breathing • Loss of appetite Chest pain • Source: ATS Silica Awareness 57 19