1. Occupational Lung Diseases: Guidelines and Approaches
Luvuyo Dzingwa
21 April 2018

2. Outline 01
Introduction 02
Effects of Occupational Lung Exposures 03
Clinical Approach 04
Social dimension 05
Summary

3. Introduction
Occupational lung diseases arise out of, and in course of employment
Occupational lung diseases are a broad group of diagnoses caused by the inhalation of dusts, fumes or noxious substances
The severity of the disease is related to the material inhaled, intensity and duration of the exposure
These diseases have been documented as far back as ancient Greece and Rome
The incidence of the disease increased dramatically with the development of modern industry
The lung is an important site of contact with these substances at workplace due to its:
Extensive surface area
High blood flow
Thin alveolar epithelium

4. Determinants of inhalational exposure
Influenced by particle
Size
Shape
Density
Chemical properties
Alkalinity & acidity
Fibrogenicity
Antigenicity
Particle clearance
Concentration in surrounding air
Duration of exposure
effectiveness of clearance mechanisms
Susceptibility of the exposed person
Immunological mechanism
NEJM 2000

5. Classification 1. Inorganic dust 2. Organic dust 4. Immunological
Pneumoconiosis means dusty lung
Permanent alteration of lung structure caused by reaction of the lung tissue as result of inhaled dust
In medicolegal practice at least, presence of dust alone is insufficient to indicate pneumoconiosis
For compensation to be considered, the mineral dust must alter the structure of the lung and cause impairment
Grain dusts – Wheat weevil (Infested wheat)
Cotton dust- Byssinosis-asthma like diseases
It produces obstructive impairment of lung function
Occupational Asthma – platinum salts
Allergic alveolitis (hypersensitivity pneumonitis)

6. (Particle –laden macrophages ,no fibrosis )
Pneumoconiosis
Fibrotic
(focal nodular &diffuse fibrosis)
Silicosis- nodular fibrosis
Coal workers’ pneumoconiosis
Asbestosis- diffuse fibrosis
Berylliosis – granulomatous reaction
Non-fibrotic
(Particle –laden macrophages ,no fibrosis )
Siderosis
Stannosis
Baritosis

7. How Do You Know it is a Pneumoconiosis?
Occupational history of exposure to a mineral or metal dust
Organic dust pneumoconioses exist but are rare
Compatible clinical and laboratory findings
Diagnosis is primarily by chest film - features consistent with pneumoconiosis .
No alternative diagnosis likely
This does not mean that it is a diagnosis of exclusion!
Pneumoconiosis is a diagnosis of context!
Silicosis can mimic
Sarcoidosis (benign inflammation of unknown cause)
Idiopathic pulmonary fibrosis (lung scarring of unknown cause)
Lung cancer
Several other lung conditions (chronic infection, collagen-vascular disease, etc.)

8. Which Common Pneumoconiosis is it?
Occupational history
Silica
Asbestosis
Coal workers’ pneumoconiosis
Chest film
Rounded opacities and cardinal features of silicosis
Irregular opacities and cardinal features of asbestosis
Pathology
biopsy rarely indicated
asbestos bodies useful for identifying asbestosis

9. Medical Evaluation of OLDs - Modalities
Primarily diagnostic
Microscopy
Chest film, CT
Spirometry, DLCO
Blood gases
Methacholine challenge
Biopsy (Ca, IPF, granulomatous disease)
Primarily occupational
Occupational history
Skin prick test/RAST
Biopsy (avoid)
Provocative testing (rare)
Impairment evaluation

10. Basic principles
The etiology may be multifactorial and occupational factors may interact with other factors
The dose of exposure is an important determinant of the of people affected or severity of the disease
Individual difference in susceptibility to exposure do exist
The effects of a given occupational lung exposure occur after the exposure within a predictable latency interval
Evidence of structural lesion consistent with the known pathological process (e.g. nodular fibrosis- silicosis )
In practice, evidence of a structural lesion is usually demonstrated by chest film with or without CT
Evidence of causation by an agent
Evidence of causation by a particular agent may be more difficult but is usually satisfied by the occupational history
Exclusion of alternative diagnoses
may require additional clinical tests and even biopsy

11. Clinical Approach History
History of present illness – useful to rule non- OD respiratory symptoms or diseases
Occupational history - essential
Employment details- Occupation, type of industry and specific work, name of employer and years employed
Exposure information- general description of job process and overall hygiene, materials used by worker and others , specific workplace exposures and use of PPEs
Details about past employments /exposures in a chronological order
Physical examination
Generally unrevealing about specific cases
Helpful in ruling out non-ODs of respiratory symptoms or diseases
Cardiac problems or connective tissue disorders
Radiography
Chest film – most often
* Chest radiographs have low sensitivity and specificity – missing as 10 to 15% of cases with pathological documented diseases
Limitations- findings can be non-specific & Interpersonal variations
** CT- Sensitivity is higher than sensitivity of chest radiograph, but not 100%
Specificity - Variable

12. Physiological methods Pathological examination
Clinical Approach
Physiological methods
Cross shift PEFRs
Pulmonary Function Testing -Vital capacity, Flow rates (e.g. FEV1), Lung Volumes and Diffusing Capacity (CO)
Bronchodilators: Pre-, Post-Shift
Bronchoprovocation Testing- Methacholine Testing and Specific Agents
Pathological examination
Methods use to obtain specimens for pathological examinations
Bronchoscopy
Thoracoscopy
Open lung biopsy
Post mortem

13. Principles of Management
When an OLD is suspected:
Diagnosis first
Document level of impairment, track
Treat according to condition
Protection at workplace to prevent progression
Pneumoconioses: removal not indicated if <OEL
Be disease: removal from exposure required
Otherwise, symptomatic treatment once fibrosis is established

14. Usually in medicine, diagnosis is primarily for treatment. Not here.
Identification
Diagnosis
Causation
Functional evaluation
Treatment
Prognosis
Medical surveillance monitoring
causation
causal circumstances
current impairment
future impairment
fitness to work
Workers’ compensation
Employer responsibility

15. Social dimension: why accurate diagnosis, causality is important.
Values
Equity
Fairness (Justice)
Sufficiency
Transparency
Standardization
Consistency
Predictability
Reliability
Rapidity
Validity

16. Importance of Occupational Lung Diseases
Knowledge of cause may affect patient management & diagnosis
May prevent further disease progression in affected person
Establishment of cause may have significant legal , financial & social implications for the patient
The recognition of occupational factors can also have important regulatory and policy consequences
Occupational lung diseases can also serve as important disease models

17. Essential Questions What is the nature of the process?
What exposure in the worker’s employment history may have been responsible?
What permanent level of impairment can be predicted?
What can be done to control or limit the disease process?
Are other people in the workplace likely to be affected, now or in the future?

18. Occupational history is mandatory
Summary
Awareness of Occupational exposure as a cause of the diseases is important
Occupational history is mandatory
Establish a work relationship
Objective evidence of exposure
Occurrence of symptoms
Alteration of lung architecture
Change in lung function is necessary
Consideration for compensation
Reduction of exposure is key to protection

19. Do you have any questions?
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