De medische aspecten van blootstelling aan kwartsstof Les aspects médicaux de l exposition à la poussière de quartz - PDF

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Blootstelling aan kwartsstof: een bekend risico? Exposition à la poussière de quartz: un risque connu? NAVB-CNAC Brussel De medische aspecten van blootstelling aan kwartsstof Les aspects médicaux

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Blootstelling aan kwartsstof: een bekend risico? Exposition à la poussière de quartz: un risque connu? NAVB-CNAC Brussel De medische aspecten van blootstelling aan kwartsstof Les aspects médicaux de l exposition à la poussière de quartz Benoit Nemery, MD, PhD Arbeids-, Milieu- en Verzekeringsgeneeskunde & Pneumologie K.U.Leuven, Belgium Dust-induced respiratory disease Effects of inhaling dust particles depend on 1. Quantity of dust inhaled concentration in air (mg/m 3 ) x duration underground mining open cast mining indoor work outdoor work Dose Quantity of material concentration in air by mass: mg/m 3 by number: n/m 3, e.g. fibres/ml by total surface area duration of exposure hours, days, years cumulative exposure: concentration x duration e.g. coal dust: g.h.m -3 asbestos: fibre-years (= fibres.ml -1.y) Dose Quantity of material concentration in air (mg/m 3 ) x amount of air inhaled (L) minute ventilation 8-10 L/min at rest 50 L/min during exercise x duration of exposure (min) m 3 air/day Cumulative dose Quantity of material concentration in air x total exposure duration (mg/m 3 ) (hours) cumulative exposure index e.g. coal dust: g.h.m -3 Dust-induced respiratory disease Effects of inhaling dust particles depend on 1. Quantity of dust inhaled 2. Size of the dust particles site of deposition in respiratory tract Anatomy larynx Upper airways Lower airways Netter. Ciba Collection Vol. 7 trachea bronchi bronchi bronchioli bronchi bronchioli alveoli O 2 CO 2 Respiratory uptake of particles Air velocity +++ Particle size 5 µm impaction ++ + sedimentation 1-5 µm 0 diffusion 0.2 µm Pleura 0.1µm Deposition of particles % deposition Particle diameter (µm) from West, fig 67 Dust sampling Inhalable or inspirable fraction ( total dust ) deposited in upper or lower respiratory tract PM 100 µm Thoracic fraction deposited beyond the larynx PM 10 µm Respirable or alveolar fraction deposited beyond the terminal bronchioles PM 5 µm Deposition of particles - host factors Flow characteristics tidal volume (exercise rest) nasal vs mouth breathing (exercise) Individual factors anatomy of airways (branching angles) airway narrowing (reflex, asthma) chronic lung disease (bronchitis, emphysema) Presence of other factors (irritants, smoking) Clearance of particles Soluble particles: dissolved in lining fluid! potential for irritation & local damage, but no persistence! potential for systemic absorption via nasal / bronchial / pulmonary circulation Clearance of particles Insoluble particles if deposition in trachea - terminal bronchioli mucociliary escalator: rapid process: t ½ = 1h-15d! individual differences effects of smoking and irritants effects of disease (acute/chronic bronchitis, CF, )! potential for systemic absorption via gut Clearance of particles Insoluble particles if deposition beyond terminal bronchioli phagocytosis by alveolar macrophages: slow process: t ½ = d mucociliary escalator lymphatic clearance mediastinal lymph nodes pleural space! toxicity for macrophages inflammation! biopersistence in lung tissue Particle clearance from West, fig 69-70 FIG69 Particle deposition & clearance v air impaction 5 µm +++ sedimentation 1-5 µm ++ + mucociliary escalator t ½ = 1h-15d diffusion 0.2 µm 0 Pleura Lymph node macrophages + lymph t ½ = d Dust-induced respiratory disease Effects of inhaling dust particles depend on 1. Quantity of dust inhaled 2. Size of the dust particles the smaller the particles, the deeper the penetration in the lung mechanisation generally leads to more hazardous dust (quantity, particle size ) 3. Nature of dust inhaled Pneumoconiosis Fibrotic disease of the lung parenchyma (focal or diffuse) caused mainly by accumulation of mineral dust or fibres (+ host reaction) Silicosis Coal worker s pneumoconiosis (CWP) Asbestosis Other pneumoconioses (talcosis,...) Mixed dust fibrosis Dust-induced respiratory disease Effects of inhaling dust particles depend on 1. Quantity of dust inhaled 2. Size of the dust particles 3. Nature of dust inhaled Quantity of free crystalline silica (SiO 2 ) silicosis Si Si Si = silicon (element) SiO 2 = silicon dioxide (silica) [Silicone = synthetic polymer] Si SiO 2 = silicon dioxide (silica) free silica combined silica Si SiO 2 = silicon dioxide (silica) free silica: SiO 2 crystalline: quartz, cristobalite, tridymite amorphous : diatomite (Kieselgur), vitreous SiO 2 combined silica: silicates SiO 2 + cations (Na, Mg, Al, ) or anions (F, Cl) e.g. talc = Mg 3 Si 4 O 10 (OH) 2, kaolin = Al 2 O 3 SiO 2 H 2 O Si SiO 2 = silicon dioxide (silica) free silica: SiO 2 crystalline: quartz, cristobalite, tridymite silicosis amorphous : diatomite (Kieselgur), vitreous SiO 2 combined silica: silicates SiO 2 + cations (Na, Mg, Al, ) or anions (F, Cl) e.g. talc = Mg 3 Si 4 O 10 (OH) 2, kaolin = Al 2 O 3 SiO 2 H 2 O no silicosis Silicosis Caused by free crystalline SiO 2 (quartz, ) mining, quarrying, tunnelling stone cutting, polishing, cleaning sandblasting abrasive & scouring powders foundries ceramics, refractory bricks, enamels construction, demolition Fubini & Hubbard Free Rad Biol Med 2003, 34, Acute silicosis Alveolar proteinosis, silico-lipoproteinosis intense exposure to very fine & freshly fractured silica particles (sandblasting, silica flour) within weeks to months poor prognosis death Silicosis Chronic simple silicosis discrete silicotic hyaline nodules in lung little or no functional consequences may progress, sometimes rapidly ( accelerated silicosis ), even after cessation of exposure, to Complicated silicosis (Progressive Massive Fibrosis = PMF) confluent noduli ( 1 cm) often + emphysematous changes evolution to cor pulmonale death Case (L.S.) Male, 30 y, never smoker diagnosis of sarcoidosis III chest X-ray, HRCT granulomas in mediastinal lymph nodes low TLC, low DLco y: operator sandblasting machine in iron foundry (closed system, but dusty) crystalline inclusions in cells Case (B.A.) Man, 59 y, smoker (40 PY) School until 14 y; then paper plant; placing stoves Facade renovation (incl. sandblasting) : 15 y for a building firm 18 y self-employed Case (B.A.) Progressive shortness of breath, especially on exercise Chest x-ray because of syncope at work PFT Case (B.A.) FVC 115% pred FEV 1 83% pred FEV 1 /FVC 57% RV (He) 83% pred TLC (He) 96% pred TLco 59 % pred Kco 66% pred 6MWT 74% pred Sandblasting jeans Courtesy Dr. Akgün, Erzurum Jeans blasting Alveolar proteinosis Acute silicosis 19 y old Courtesy Dr. Akgün, Erzurum J Occup Health 2005, 47, y old Eur Respir J 2008, 32, Akgun et al. ERJ 2008, 32, Turkey, Bingöl (near Erzurum) 157 former denim sanblasters, all males mean age: 23 y [15-44 y] start work: 17 y [10-38 y] duration: 3 y [1-120 months] Akgun et al. ERJ 2008, 32, former denim sandblasters Mostly unregistered workplaces 2-12 sandblasting devices/workplace use of sifted sea sand h/d (2 shifts, sleeping on premises), 6-7 d/w no exhaust ventilation, 1-2 face masks/day jeans/day, 3,000-5,000 skirts/day Apprentices & foremen Akgun et al. ERJ 2008, 32, respiratory symptoms in 131 subjects (83%) dyspnea 52% chest pain 46% x-ray silicosis in 77 subjects (53%) ILO Category 0 68 (47%) [0/- 52; 0/0 3; 0/1 13] ILO Category 1 35 (24%) [1/0 19; 1/1 9; 1/2 7] ILO Category 2 16 (11%) [2/1 4 ; 2/2 2; 2/3 10] ILO Category 3 26 (18%) [3/2 8 ; 3/3 6; 3/+ 12] Large opacities 14 (10%) [A 6; B 3; C 5] Akgun et al. ERJ 2008, 32, Si SiO 2 = silicon dioxide (silica) free silica: SiO 2 crystalline: quartz, cristobalite, tridymite silicosis t amorphous : diatomite (Kieselgur), vitreous SiO 2 combined silica: silicates no silicosis SiO 2 + cations (Na, Mg, Al, ) or anions (F, Cl) e.g. talc = Mg 3 Si 4 O 10 (OH) 2, kaolin = Al 2 O 3 SiO 2 H 2 O Case A Case A MSDS of Clarcel : calcined activated diatomaceous earth cristobalite ( 60%) & quartz ( 3%) TLV-TWA amorphous Si = 10 mg/m 3 quartz = 0.1 mg/m 3 cristobalite = 0.05 mg/m 3 dust measurements (made later): total inhalable dust: 11.5 mg/m 3 respirable dust: 3.5 mg/m 3 10. RX thorax Referred for evaluation of sarcoidosis Mediastinoscopy: lymph node Silicosis Involvement of hilar/mediastinal lymph nodes enlargement + calcifications ( egg shell ) may be early (sole) manifestation of silicosis DD other causes of hilar lymphadenopathy (sarcoidosis, lymphoma, ) possible pathogenic role in PMF (impaired lung clearance) possible complications: broncholithiasis, broncho-oesophageal fistula, left laryngeal palsy Case (VG.A.) Presents with hoarseness Hilar adenopathies on chest x-ray Initial diagnosis of sarcoidosis Machine operator in plant producing sand Diagnosis of silicosis Unusual cases Domestic silicosis Dumontet et al. Acute silicosis due to inhalation of a domestic product. Am Rev Respir Dis, 1991, 143, y old woman with acute silicosis: inhalation of Ajax scouring powder (90% silica) 3 times per day (nice smell) over past 6 months Dumontet et al. Silicosis due to inhalation of domestic cleaning powder. Lancet, 1991, 338, 1085 second case (17 y old woman) with hilar lymphadenopathy Järveläinen et al. A woman with nodules in her lungs. Lancet, 1998, 351, y old woman with chest nodules (DD metastases): for past 2½ years several spoonfuls per day of a silica-containing powder (40% glucose, 32.4% silica crystals, 19.5% cherry extract, 5.5% fructose with blackcurrant extract) prescribed by a nature healer Silicates Si SiO 2 = silicon dioxide (silica) free silica: SiO 2 crystalline: quartz, cristobalite, tridymite silicosis amorphous : diatomite (Kieselgur), vitreous SiO 2 combined silica: silicates SiO 2 + cations (Na, Mg, Al, ) or anions (F, Cl) e.g. talc = Mg 3 Si 4 O 10 (OH) 2, kaolin = Al 2 O 3 SiO 2 H 2 O! often: contamination by free SiO 2 (+ to +++) no silicosis Si SiO 2 = silicon dioxide (silica) free silica: SiO 2 t crystalline: quartz, cristobalite, tridymite silicosis amorphous : diatomite (Kieselgur), vitreous SiO 2 combined silica: silicates SiO 2 + oxides of Mg, Al, Fe, e.g. talc = Mg 3 Si 4 O 10 (OH) 2, kaolin = Al 2 O 3 SiO 2 H 2 O often: contamination by free SiO 2 (+ to +++) + may cause lung disease silicatosis no silicosis Talc Mg 3 Si 4 O 10 (OH) 2 + varying proportions of impurities, incl. quartz & tremolite talc pneumoconiosis talco-silicosis, talco-asbestosis talcosis: interstitial lung disease, possibly with granulomas Complications of silicosis Tuberculosis Bronchopulmonary cancer (IARC group 1) Autoimmune disease Systemic sclerosis (Erasmus syndrome) Rheumatoid arthritis (Caplan syndrome) Lupus erythematosus Renal disease! Also without pulmonary silicosis Dust-induced respiratory disease Pneumoconioses Chronic rhinitis & sinusitis Chronic bronchitis & chronic obstructive pulmonary disease (COPD) Lung cancer (radon) COPD and occupation Cross-sectional studies Longitudinal studies Mineworkers (coal, hard-rock, gold,...) independently of pneumoconiosis Other industrial workers (steelworkers, welders, cement, CdO, exposure to irritant gases,...) Farmers and agro-industry (textile, grain, intensive pig farming) «industrial bronchitis» accelerated decline in FEV 1 COPD and occupation American Thoracic Society Statement: Occupational contribution to the burden of airway disease. Am J Respir Crit Care Med 2003, 167, Literature-based estimation of population attributable risk (PAR) for asthma and COPD due to occupational exposures Asthma: median PAR 15% (21 studies) COPD: PAR ~15% Chronic bronchitis (8 studies): median 15% [4-24%] Airflow obstruction (5 studies): median 18% [12-55%] COPD and occupation Blanc PD, Torén K. Occupation in chronic obstructive pulmonary disease and chronic bronchitis: an update. Int J Tuberc Lung Dis 2007, 11, studies since 2000 chronic bronchitis (8 studies): median PAR 15% [0-34%] COPD (8 studies): median PAR 11% [0-37%] + adverse impact of COPD on working-life (work disability) COPD and occupation Blanc et al. Occupational exposures and the risk of COPD: dusty trades revisited. Thorax 2009, 64, 6-12 subjects (40-65 y) from Kaiser Permanente 1202 with COPD (742 with GOLD 2-4) 302 matched control subjects Telephone interview, then Spirometry Self-reported exposure to vapours, gas, dust or fumes (VGDF) + Job-Exposure Matrix (JEM) [longest held job] COPD subjects: lower educational attainment, less $, more smokers (13% NS), more «dirty» jobs COPD and occupation Blanc et al. Occupational exposures and the risk of COPD: dusty trades revisited. Thorax 2009, 64, 6-12 VGDF exposure: adj. OR 2.11 [ ] PAF 31% JEM high exposure: adj. OR 2.27 [ ] PAF 13% Joint influence of smoking and VGDF: adj. OR COPD GOLD 2+ Never S / no VGDF Never S / VGDF 1.98 [ ] 1.69 Ever S / no VGDF 6.71 [ ] 8.31 Ever S / VGDF 14.1 [ ] 18.7 Thank you for your attention
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