Save Your Breath: The Lung s Response to Air Contaminants. CROET Spring 09 Symposium William Lambert, PhD

Transcription

1 Save Your Breath: The Lung s Response to Air Contaminants CROET Spring 09 Symposium William Lambert, PhD lambertw@ohsu.edu

2 Learning Objectives Understand 1. Structure and function of lung 2. Processes of deposition and dose 3. Disease outcomes 4. Examples of pollutants and health effects 5. Occupational asthma 6. Basics of spirometry for surveillance 7. Opportunities for intervention

3 Why is the lung the most important route of exposure? Barrier Surface Area (m 2 ) Thickness (µm) Weight (kg) Daily exposure (kg) Skin variable GI tract Lungs

4 Primary Function: Gas Exchange

5 Upper Respiratory Tract Nasal and oral cavities Purposes: 1. Filtration and elimination 2. Humidification Relevant aspects for pulmonary exposure Direct path to brain Deposition µm Water soluble Ammonia reaction

6 Mid Respiratory Tract Trachea, bronchi, and bronchioles Purpose: 1. Conduction and airflow 2. Filtration and clearance Relevant aspects Deposition Muco-ciliary ladder 24-hr retention time Smooth muscle and bronchoconstriction

7 Asthma

8 Lower Respiratory Tract Alveoli (air sacs) Purpose: 1. Gas exchange Relevant aspects: Thin, easily damaged

9 Mechanisms of Particle Deposition Determinants: Size Shape Density Velocity Solubility Static charge

10 Deposition: Size Matters! Inhalable < 10 µm Non-inhalable > 10 µm Respirable < 2.5 µm Ultrafine < 1 µm

11 Ultrafine Particle Deposition

12 Examples of Contaminants Tobacco smoke (most common) Carbon monoxide (asphyxiant gas) Ozone (photochemical smog - outdoor) Asbestos (mineral fiber) Dusts (silica) Radon progeny (alpha emitter)

13 Tobacco Smoke Complex mixture of particles and chemicals Prevalence of smokers US 20.8% OR 18.5% WA 17.6% Health effects are wide ranging Similar for direct and secondhand exposure Emphysema and lung cancer

14 Oregon Smoke-free Workplace Law Effective January 1, 2009 Smoking is prohibited in most public places and workplaces Penalties - $500 per day (maximum $2000 in 30- day period) Includes bars, bingo halls, and work vehicles No smoking within 10-ft of doors, windows, and ventilation intakes

15 Carbon Monoxide (Asphyxiant) Source - combustion Odorless and colorless Binds to hemoglobin with >200 x affinity of oxygen Double whammy High oxygen demand tissues most affected Brain Heart muscle Protect at 2% COHb 35 ppm one-hour TWA 9 ppm 8-hour TWA

16 CO Intoxication Examples Insidious Colorless Odorless Tasteless Telltale symptoms - Headache, nausea Fatigue, balance Immediate intervention

17 Ozone Formed by reaction of NOx and VOCs in heat and sunlight Reactive, watersoluble Protection indoors Reduced lung growth and function in school children Premature death

18 Natural fiber Friable Lengths and diameters are polydisperse << 10 µm Behave like javelins in airstream Both physical and chemical toxic effects Asbestosis (scarring) Mesothelioma (very specific lung cancer) Asbestos

19 Asbestos Examples At-Risk for Exposure Bystanders and building occupants 1. Housekeeping or custodial 2. Maintenance and skilled workers 3. Abatement (removal workers) 4. Firefighters and emergency personnel

20 Pneumoconiosis Exposure to dusts Scarring and stiffening Restrictive disease that prevents the lung from expanding fully Black Lung Disease in coal workers Silicosis in miners and sand blasters

21 Radon Progeny Odorless, colorless gas Naturally occurring 15% of all US lung cancer 226 Rn --> 218 Po, series of alpha particle decays, within days to minutes equivalent to helium nucleus leaves dense track of damage in lung epithelium Direct ionization of DNA via hydroxyl radical reaction The Decay Chain

22 How does radon gas enter a building?

23 Radon Testing and Mitigation Test 2-7 days in shut home Charcoal canister Track etch TV room and bedroom US action level = 4 pci/liter Smokers and secondhand smokers at increased risk Progeny attach to respirable-sized suspended particles Longer retention in lung Response (lung ca risk) 1½ packs 1 pack ½ pack NS Dose (pci/l)

24 Work-Related Asthma SIGNS & SYMPTOMS Reduced expiratory flow (PEF) Inflammation Mucous hypersecretion Wheezing Shortness of breath (dypsnea) Cough WA INCIDENCE to 12.9 claims per 100,000 FTE worker years increase 8 yrs CAUSES Genetic predisposition (atopy) Repeated exposures lead to sensitization; response often delayed IgE mediated response Animal dander Western red cedar Molds and fungi Endotoxin Non-IgE mediated response Exertion (exercise) Infections Tobacco smoke Isocyanates

25 Asthma Hazards by Sector and Job Industry/Occupation Agent(s) Milling/Baking Flour, insects, mite debris Agriculture Animal antigens, dusts Health care Latex, formaldehyde Grain handler Grain, insect debris, dust Laboratory worker Animal antigens Lumber and woodworking Wood dusts (plicatic acid) Paper product manufacture Natural glues Airplane/sporting manufacture Epoxy resins Painting Isocyanates, chromium (VI) Plastics industry Isocyanates, anhydrides Metals Industry Food Service Stainless/galvanized steel, chromium (VI) Tobacco smoke

26 Pulmonary Function Tests Normal: FEV1/FVC > 75%, e.e., get at least 3/4 air out in first second

27 Spirometry

28 Lung Mechanics: Volumes and Capacities Total Lung Capacity Vital Capacity Tidal Volume Functional Residual Capacity Residual Volume Adapted from Gordon and Amdur (1991)

29 Flow-Volume Loop Normal Obstructive

30 Reversibility Bronchodilator Use

31 Patterns of Ventilatory Function OBSTRUCTIVE Reduced flow rates and normal volumes Excessive mucus production Inflammation Bronchoconstriction Asthma, chronic bronchitis, emphysema RESTRICTIVE Reduced volumes and normal flow rates Damage to lung tissue Fibrosis and scarring Physical deformity (rib cage, removal of lung) Pneumoconiosis COMBINED e.g., Cystic Fibrosis NORMAL Lung volumes and flow rates within normal range for age, gender, and height

32 COPD = Chronic Obstructive Pulmonary Disease Bronchitisbronchiolitis -inflammation -secretions Emphysema -alveolar enlargement -damage to alveolar septa Chronic airflow limitation and resistance to expiratory flow

33 Strategies for prevention? Primary Prevention Secondary Prevention Tertiary Prevention Engineering Controls Behavior Change PPE Screening Reduce susceptibility Early dx and treatment Fate & Dispersion Behavior Pharmacokinetics Responsiveness Source Removal Source Presence Exposure Dose Health Effect

34 Quiz: Workers at one food plant in Missouri Chronic cough Shortness of breath Skin problems Spirometry showed obstructive pattern Not reversible with bronchodilator Most prevalent in mixing area Exposures: corn kernels, heated soybean oil, salt, and butter flavor

35 Answer: Exposures: corn kernels, heated soybean oil, salt, and butter flavor A microwave popcorn plant! Could it be the oil? Salt dust? Flavoring? Assays on rats confirmed diacetyl flavoring also observed health effects in bakery workers years before