Occupational History of Coal Mining and its Association with Restrictive and Obstructive Lung Disease Among Males in Two Counties in Rural Appalachian Kentucky Public

Abstract

Objective. Appalachian (Eastern) Kentucky has a high burden of lung disease, partially attributable to significant occupational exposure to coal mine dust in the 7th largest coal producing state in the United States. Cases of coal workers’ pneumoconiosis and its most severe form, pulmonary massive fibrosis, began increasing significantly in Central Appalachia, and Appalachian Kentucky in particular, around 2000. There is a need to better understand the association between coal mine dust lung disease and coal mining exposure in Eastern Kentucky to better guide prevention efforts and operating practices.

Methods. The analysis utilized cross-sectional data from the University of Kentucky, obtained in Harlan and Letcher counties between 2015 and 2017. Multivariable Poisson regression with robust standard errors was performed to assess the association between lung disease, defined by spirometric pattern as obstructive, restrictive, or normal, and coal mining history, defined as never, underground only, surface only, and both types, adjusted for age, education, smoking level, and history of other dusty jobs. Adjusted prevalence ratios (aPR) and 95% confidence intervals (CI) were obtained. The adjusted analyses were further stratified by age and coal mining tenure.

Results. The aPR for the association between obstructive lung disease and a history of underground coal mining, surface coal mining, and underground and surface coal mining were 1.45 (95% CI: 0.94-2.25), 1.20 (95% CI: 0.71-2.02), and 1.51 (95% CI: 0.96-2.38), respectively. The aPR for the association between restrictive lung disease and a history of underground coal mining, surface coal mining, and underground and surface coal mining were 1.18 (95% CI: 0.74-1.90), 0.997 (95% CI: 0.71-2.02), and 1.51 (95% CI: 0.96-2.38), respectively.

Conclusions. The observed effects for this study demonstrated much stronger associations for obstructive lung disease compared to restrictive lung disease and for underground coal mining and both types of coal mining compared to surface coal mining. Generally, the effects of the association for the older age group and longer coal mining tenure group were stronger than the younger age group and shorter mining tenure group, respectively. The analyses were limited by a lack of statistical power and potential survival bias.

Table of Contents

CHAPTER 1: LITERATURE REVIEW 1

Public Health Significance 2

Coal mining 4

The history of coal production in the United States 4

Coal mining by region 5

Coal mining in Kentucky 6

Coal mining methods 6

Coal rank 7

Pulmonary function and spirometry 7

Spirometry 7

Spirometry interpretation 8

Obstructive pattern of pulmonary function impairment 8

Restrictive pattern of pulmonary function impairment 9

Spirometry pattern in coal mine dust lung disease (CMDLD) 9

Coal mine dust lung disease (CMDLD) 10

Introduction to CMDLD 10

CMDLD prevention and industry regulation 10

Restrictive coal mine dust lung diseases 12

Introduction 12

Radiographic classification of pneumoconioses 12

Coal workers’ pneumoconiosis (CWP) 13

Coal mine dust composition 14

CWP Pathophysiology 14

Clinical presentation 15

Silicosis 15

Mixed-dust pneumoconiosis (MDP) 16

Dust-related diffuse fibrosis (DDF) 16

Obstructive coal mine dust lung disease 17

Introduction 17

Chronic obstructive pulmonary disease (COPD) 17

Chronic bronchitis 17

Emphysema 18

Clinical features 18

COPD and coal mining 18

Coal workers’ pneumoconiosis epidemiology and trends 19

Risk factors for Coal Mine Dust Lung Disease 23

Study rationale 24

CHAPTER 2: MANUSCRIPT 26

Abstract 27

Objective 27

Methods 27

Results 27

Conclusions 27

Introduction 28

Methods 32

Study design and sample 32

Outcome variable 35

Exposure variable 36

Covariates 37

Statistical analysis 39

Results 41

Descriptive statistics 41

Multivariable adjusted model 43

Multivariable adjusted model stratified by age 43

Multivariable adjusted model stratified by coal mining tenure 44

Discussion 45

Tables and Figure 50

Figure 1 50

Table 1 51

Table 2 54

Table 3 54

Table 4 55

Table 5 55

Table 6 56

Table 7 56

Table 8 57

CHAPTER 3: FUTURE DIRECTIONS/PUBLIC HEALTH IMPLICATIONS 58

Recommendations 59

Future research 59

Policy 59

REFERENCES 60

About this Master's Thesis

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School	Rollins School of Public Health
Department	Executive Masters of Public Health - MPH
Subfield / Discipline	Applied Epidemiology
Degree	M.P.H.
Submission	Master's Thesis
Language	English
Research Field	Health Sciences, Epidemiology Health Sciences, Public Health Health Sciences, Occupational Health and Safety
Mot-clé	Spirometry Coal workers' pneumoconiosis Coal mine dust lung disease Occupational exposure Obstructive lung disease Central Appalachia Pulmonary massive fibrosis Restrictive lung disease Occupational medicine Coal mining Appalachian Kentucky
Committee Chair / Thesis Advisor	Anke Huels, Emory University
Committee Members	Steven Browning, University of Kentucky Wayne Sanderson, University of Kentucky

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