Pub Health 4310 Health Hazards in Industry

1. Pub Health 4310Health Hazards in Industry Dave Wallace Lecture 6 Dusts and Pneumoconiosis

2. DUSTS AND PNEUMOCONIOSES Objectives: • This class session is intended to provide an overview of the health hazards and characteristics of important particulates that may be encountered in the workplace. • Students should be able to: • Identify a variety of particulate hazards • Know about diseases of particulate exposure, including disease mechanisms • State methods of controlling particulate exposure PH 4310 - Health Hazards in Industry, Lct 6

3. DUSTS AND PNEUMOCONIOSES Introduction: • Many toxic agents occur as particulates. • Factors which affect the hazard • Particle size • Other physical characteristics. • Many important diseases are caused by particulate exposure • Great many workers have suffered • Dust exposure continues to be a serious industrial hygiene concern. • There are too many cases of silicosis and other pneumoconiosis. PH 4310 - Health Hazards in Industry, Lct 6

4. DUSTS AND PNEUMOCONIOSES Definitions: • Particulate matter: Fine solid or liquid particles, such as dust, fog, mist, smoke or sprays. • Aerosol: Liquid droplets or solid particles dispersed in air. • Dust: Solid particles generated by mechanical action, (crushing, grinding, impact, etc.) • Fume: Solid airborne solid particles formed by condensation of vapor (i.e., welding fumes). PH 4310 - Health Hazards in Industry, Lct 6

5. DUSTS AND PNEUMOCONIOSES Definitions: • Mist: Suspended liquid droplets generated by condensation or atomization. (Fogs are formed by condensation). • Smoke: An aerosol of fine particle matter originating from combustion. Smoke usually contains droplets and dry particles • Fiber: at least 3:1 aspect ratio • Pneumoconiosis: “Dusty lung disease”, the accumulation of dust in the lugs and the tissue reaction to its presence PH 4310 - Health Hazards in Industry, Lct 6

6. DUSTS AND PNEUMOCONIOSES Particle Physics • Physical characteristics of dust particles affect • How they settle out from the air • How they are deposited in the lung • How they adhere to other particles and surfaces • Particle size in a population • Particles may be essentially the same size (monodisperse), often artificially created • Different sizes, (polydisperse) • Particles usually are logarithmically distributed PH 4310 - Health Hazards in Industry, Lct 6

7. Logarithmic particle distribution in air • From the 1973 original NIOSH “white book”, The Industrial Environment, its Evaluation and Control PH 4310 - Health Hazards in Industry, Lct 6

8. DUSTS AND PNEUMOCONIOSES Particle Physics (cont.) • Probability-log graph shows the distribution of particle size, mass, and surface area. • For this distribution: • Mean diameter = 1.5 μm (micrometers) • Mean surface area = 4.2μm (micrometers) • Mean mass = 7.8 μm (micrometers) • Toxicity may be affected by factors of mass, particle size, and surface area PH 4310 - Health Hazards in Industry, Lct 6

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10. DUSTS AND PNEUMOCONIOSES Particle Physics (cont.) • Physical characteristics of dust particles affect how they settle out from the air and how they are deposited: • For particles from about 1 to 50 microns diameter, the settling velocity is a function of the specific gravity, ρ and diameter, d in μm (micrometers) PH 4310 - Health Hazards in Industry, Lct 6

11. DUSTS AND PNEUMOCONIOSES Particle Physics (cont.) • Larger particles can settle out of the air by gravity • Small particles have very low settling velocity but they are removed from the air by attractive forces • Particles attach to other particles • Agglomerates form, which rapidly settle • Particles attach to surfaces • Humidity increases attractive forces • Moisture on particles increases mass and surface area PH 4310 - Health Hazards in Industry, Lct 6

12. DUSTS AND PNEUMOCONIOSES Particle Physics (cont.) • Deposition in the body • Larger particles are trapped in the mucous of the airways and moved out of the lung by the action of cilia, the “mucociliary escalator” • >10 μm particles are deposited in the upper respiratory tract (nose and throat) • 5-10 μm particles are deposited in the airways of the lung • <5 μm particles are deposited in the respiratory bronchioles and alveoli • Removed by macrophages (white blood cells) PH 4310 - Health Hazards in Industry, Lct 6

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14. DUSTS AND PNEUMOCONIOSES Diseases: • Occupational asthma • An immunological response • Sensitized individuals suffer from constricted airways (“wheezing”) upon exposure to certain dusts. • Particulates that may cause asthma include: • Grain and cereal dusts • Wood dust, especially western red cedar and hardwoods • Detergent enzymes • Isocyanates (these may be vapors or mists) • Solder fumes (colophony or rosin) PH 4310 - Health Hazards in Industry, Lct 6

15. DUSTS AND PNEUMOCONIOSES Diseases: • Occupational asthma (cont.) • OELs for allergic responses are set to prevent initial sensitization. • OELs will not protect workers who have become sensitized • Once a person has become sensitized, they usually must seek another line of work. PH 4310 - Health Hazards in Industry, Lct 6

16. DUSTS AND PNEUMOCONIOSES Diseases (cont.): Byssinosis • Caused by exposure to dust from cotton, flax and hemp. • Characterized by airway constriction, but is not an immunological response. • Affected individuals suffer from “chest tightness”, cough, and shortness of breath. • Symptoms usually occur when workers return on Monday after a weekend away from exposure. PH 4310 - Health Hazards in Industry, Lct 6

17. DUSTS AND PNEUMOCONIOSES • Diseases (cont.): • Byssinosis (cont.) • …those who hackle in the flax and hemp to prepare it for being spun and wove, afford frequent instances of the unwholesomeness of their trade; for there files out of this matter a foul mischievous powder, that entering the lung by the moth and throat, causes continual coughs and gradually makes way for an asthma . . . but at the long run if they find their affliction grows upon them they must look out for another trade; for ‘tis a sordid profit that’s accompanied with the destruction of health. • Bernardino Ramazzini, 1705 PH 4310 - Health Hazards in Industry, Lct 6

18. DUSTS AND PNEUMOCONIOSES Diseases (cont.): • Extrinsic Allergic Alveolitis (hypersensitivity pneumonitis, or HP) • Allergic type response that affects the lung parenchyma rather than the airways. • Sensitized individuals suffer from fevers, chills shortness of breath and cough • Symptoms occur 4 - 8 hours after exposure. • Names of various conditions reflect the cause: • Farmer’s lung, mushroom worker’s lung, malt worker’s lung, bird fancier’s lung, coffee worker’s lung, etc., PH 4310 - Health Hazards in Industry, Lct 6

19. DUSTS AND PNEUMOCONIOSES Diseases (cont.): • Pneumoconiosis • Caused by small particles that collect in the alveolar areas of the lung. • Scarring (fibrosis) of the lung tissue results from inflammatory response to these particles. • The disease is “progressive” • Symptoms increase as time passes PH 4310 - Health Hazards in Industry, Lct 6

20. DUSTS AND PNEUMOCONIOSES Diseases (cont.): • Silicosis • Pneumoconiosis caused by exposure to crystalline silica • Observed among miners since the times of the Greeks and Romans. • In Bernardino Ramazzini, the “founder of occupational medicine”, wrote, • “We must not underestimate the maladies that attack stonecutters, sculptors, quarrymen, and other such workers. When they hew and cut marble underground or chisel it to make statues and other objects, they often breathe in the rough, sharp, jagged splinters that glance off." PH 4310 - Health Hazards in Industry, Lct 6

21. DUSTS AND PNEUMOCONIOSES Diseases (cont.): • Silicosis (cont.) • The nations worst industrial disasters • Work began on the Hawks Nest Tunnel near Gauley Bridge, West Virginia, in 1930 • At least 476 workers died over the next 5 years from silicosis • Death toll could be as high more than 700 • Factors which contributed to the disaster • Rock with a high silica content • New power equipment which created more dust • Dire financial conditions of the Great Depression • Desire for profits regardless of the human cost • http://www.wvculture.org/history/wvhs122.html PH 4310 - Health Hazards in Industry, Lct 6

22. Jackleg pneumatic drill PH 4310 - Health Hazards in Industry, Lct 6

23. DUSTS AND PNEUMOCONIOSES Diseases (cont.): • Silicosis (cont.) • Disease mechanisms • Macrophages die after ingesting silica particles, • Cellular contents cause Inflammation and fibrosis • Process repeats when new macrophages ingest particles • Silica was recently identified as a carcinogen. • Silica exposure continues to be a serious hazard. • More than one million U.S. workers are exposed • Mining, abrasive blasting, and construction • More than 250 die annually • OSHA and NIOSH have increased awareness and enforcement: http://www.osha-slc.gov/SLTC/silicacrystalline/index.html http://www.cdc.gov/niosh/topics/silica/default.html PH 4310 - Health Hazards in Industry, Lct 6

24. 1996 CDC report on silicosis mortality emphasizes the continuing importance of this disease. PH 4310 - Health Hazards in Industry, Lct 6

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26. DUSTS AND PNEUMOCONIOSES Diseases (cont.): • Asbestosis • A pneumoconiosis caused by exposure to asbestos fibers. • Small fibers penetrate the lung to the alveolar space, where they have an action similar to silica. • Macrophages die after ingesting fibers longer than 5 µm in length, leading to a continual process of fibrosis. PH 4310 - Health Hazards in Industry, Lct 6

27. DUSTS AND PNEUMOCONIOSES Diseases (cont.) • Berylliosis • Caused by chronic exposure to beryllium • Also known as chronic beryllium disease • Acute exposure can cause irritation, chest pain, difficulty breathing • http://chppm-www.apgea.army.mil/documents/FACT/64-003-0302.pdf PH 4310 - Health Hazards in Industry, Lct 6

28. DUSTS AND PNEUMOCONIOSES Diseases (cont.): • Metal Fume Fever • Flu-like condition caused by inhalation of metal fumes. • The most common cause is exposure to zinc oxide fumes from galvanizing operations, or cutting of galvanized steel. • Symptoms usually are worse when workers return after a period away from the job, after vacation or weekends, etc. PH 4310 - Health Hazards in Industry, Lct 6

29. DUSTS AND PNEUMOCONIOSES Diseases (cont.): • Polymer Fume Fever • Similar to metal fume fever, but it is caused by exposure to fumes from Teflon (PTFE). • Caused when workers cut Teflon-lined drums with a cutting torch • Other situations where they breathe fumes from heated Teflon. • NIOSH investigated a case where workers were exposed when they smoked contaminated cigarettes: • http://www.cdc.gov/mmwr/preview/mmwrhtml/00051631.htm PH 4310 - Health Hazards in Industry, Lct 6

30. DUSTS AND PNEUMOCONIOSES Diseases (cont.): • Cancer • Cancer may be caused by exposure to particulates. • Lung cancer from asbestos exposure and possibly by other mineral fibers. • Synergistic effect between smoking and asbestos exposure. • Mesothelioma, cancer of the lining of the lung • Caused by exposure to asbestos fibers. • Other mineral fibers may cause cancers • High levels of mesothelioma in Turkey where non-asbestos fibrous minerals are found. • Silica also has recently been identified as a carcinogen PH 4310 - Health Hazards in Industry, Lct 6

31. DUSTS AND PNEUMOCONIOSES Diseases (cont.): • Control • Dust exposure controlled by wetting, ventilation, or by the use of personal protective equipment. • Substitution is often the best bet for abrasive blasting with silica • Slag products may contain hazardous metals. • OSHA online “silica advisor” at http://www.osha-slc.gov/SLTC/etools/silica/index.htmldetails control methods for silica exposure. • OEL’s for allergic responses are set to prevent initial sensitization. PH 4310 - Health Hazards in Industry, Lct 6

32. Characteristics of particles PH 4310 - Health Hazards in Industry, Lct 6

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35. DUSTS AND PNEUMOCONIOSES References • http://www.cdc.gov/niosh/77_181.html “Occupational Diseases: a Guide to Their Recognition” • http://www.cdc.gov/niosh/86-102.html, “Occupational Respiratory Diseases” PH 4310 - Health Hazards in Industry, Lct 6