Lecture 15: Occupational lung disease Flashcards
What % of lung disease is related to COPD?
32%
What % of lung disease is related to non-asbestos lung cancer?
22%
What % of lung disease is related to asbestos lung cancer?
20%
What % of lung disease is related to mesothelioma?
20%
What occupational lung diseases are there?
COPD
Malignant diseases - lung cancer (asbestos and non asbestos related) - mesothelioma
Occupational asthma
Pneumoconioses (mineral dust)
What are the pneumoconioses?
Coal Workers’ Lung
Asbestosis
Silicosis
Who gets silicosis?
Slate workers Potters Knife grinders Hard rock miners Sand-blasting Foundry workers
What is silicosis?
Fibrotic lung disease
Activation of macrophages
Restrictive lung function deficit
Eggshell calcification of lymph nodes
How can you improve pneumoconiosis?
Prevent further exposure
Stop smoking
Monitor lung function
Symptomatic treatment
What are the benign consequences of asbestos exposure?
Pleural plaques (marker of exposure)
Benign pleural effusion
Pleural thickening (with subsequent restriction on lung function)
Asbestosis- interstitial lung disease-restrictive lung function (FEV1/FVC> 0.7) with reduction in forced vital capacity (FVC) and reduced gas transfer
What are the malignant consequences of asbestos exposure?
Lung cancer
Mesothelioma
What is the relative risk of lung cancer in asbestosis?
7x in non-smokers
93x in smokers
What is mesothelioma?
Malignancy of pleura and peritoneum caused by asbestos
Consider in with patient with history of asbestos exposure
- Pleural plaques on previous chest x-rays
- Persistent unexplained chest pain
- Weight loss
- Breathless/unilateral pleural effusion
What are the two scenarios of occupational asthma?
Occupational asthma that is caused by workplace exposures
Work-aggravated asthma in which pre-existing cases are made worse by factors in the workplace
What are the differentials of occupational asthma?
COPD
Heart failure
Interstitial lung disease
What are other risk factors of occupational asthma?
Atopy
Rhinitis
Smoking
What are the roles of challenge testing?
Confirm diagnosis when new agent blamed
Identify responsible agent when multiple sensitisers in workplace
Confirm diagnosis when history & PEFR records are equivocal
(Rarely) to exclude diagnosis in patient who will otherwise lose their job
How is challenge testing carried out in asthma?
Asthma should be stable
Withhold bronchodilators
A placebo exposure day is advisable
Equipment that delivers known concentration of suspected agent
Monitor spirometry for several hours after each increase in exposure dose
May take several days
What are the high molecular weight molecules associated with allergic occupational asthma?
Proteins, polysaccharides
80-90% cases
Sensitisation with latency period (weeks-years)
IgE-dependent
Skin prick/allergy testing
- Flour (bakers)
- Animals (farmers)
- Latex
- Enzymes (eg detergents)
What are the low molecular weight molecules associated with allergic occupational asthma?
Mechanism poorly understood
Usually independent of IgE
Limited utility of skin prick/allergy testing
- Isocyanates (printing, plastics)
- Metals (welders)
- Dyes (hairdressers)
What is irritant-induced (non-allergic) asthma?
Direct effect on airways, not immune-mediated, occurs without pre-existing asthma
Acute:
- Reactive Airways Dysfunction Syndrome (RADS)
- Develops within hours of a single, very high exposure to an irritant
Subacute:
- Insidious onset of asthma symptoms after multiple moderate/high exposure incidents
What are some causative agents of RADS?
Caustic vapours Ammonia Fire/Smoke Chlorine Tear Gas Floor Sealants
What is a toxin?
A naturally occurring poison produced within living cells or organisms
Botulinum, Ricin, Snake venom
What is a pollutant?
Any substance that contaminates the environment
What are the different factors that are important in exposure?
Concentration of toxin/pollutant
Duration
Intensity (exercise etc)
Route (skin vs inhaled)
Metabolism of toxin
What are the different factors that are important in susceptibility?
Genetic factors - protective effect of HbS against falciparum malaria
Co-morbidity / underlying diseases that augment clinical impact of toxic load
Environmental factors - heat waves, cold snaps, smogs
What are primary pollutants from vehicle exhausts?
From fossil fuel combustion
- Nitrogen oxide
- Sulphur dioxide (diesel)
- Carbon monoxide
- Particulate matter
What are secondary pollutants from vehicle exhausts?
From reactions between pollutants in the atmosphere
What are the outdoor sources of NO?
Vehicle exhausts
Power stations
What are the indoor sources of NO?
Fuel burning cookers
Unflued heaters
Cigarette smoke
What is the importance of NO in lung disease?
Associated with COPD and asthma related morbidity and mortality
Augments response to inhaled allergens
Increases likelihood that URTI will cause wheezing in children
What are the health effects of ground level ozone?
Decrease lung function
Pro-inflammatory effects:
- Increase cytokines (IL-6, IL-8, GM-CSF)
- Neutrophilic bronchitis
Increase response to inhaled allergens
Increase respiratory morbidity
What airway elements are affected by particulate matter in asthma?
Airway cilia
Mucous production
Oxidative stress to cell DNA
Induction of epithelial apoptosis
Promotes airway inflammation and ↑ IgE production
How can you reduce occupational exposure?
FFP masks
ventilation
How can you reduce environmental exposure?
Air quality warnings
Remain indoors, close windows
Minimise duration/intensity of outdoor activities
