Despite continuous efforts to eliminate asbestos from commercial use, it remains a serious occupational and environmental hazard. Health Risk Assessment for Asbestos and Other Fibrous Minerals provides a rigorous discussion of risk assessment methodology for elongate mineral particles, covering basics, theory, models, and practical applications, enabling readers to participate in carrying out efficient and informed health risk assessments, to estimate potential adverse effects for exposed populations, and to determine the acceptability of risks at a given level of exposure.
Coverage includes: - Mineralogy, health effects, pathology, exposure assessment, modeling, and characterization of risks for asbestos and similar toxic materials- Necessary integration of epidemiology, toxicology, industrial hygiene, and environmental health expertise when performing a health risk assessment- Emerging and not-well-known hazards, e.g. erionite and other naturally occurring fibrous minerals- Contributions by Garry Burdett, Bruce Case, Lucy Darnton, Daniel Hall, Arseniy Korchevskiy, Brooke Mossman, Cassidy Strode, Robert Strode, and Ann Wylie- Case studies and examples of risk calculations
Health Risk Assessment for Asbestos and Other Fibrous Minerals is a highly practical reference on the subject for occupational and public health professionals, industry and government regulators, industrial hygienists, and risk assessors, along with epidemiologists, biostatisticians, toxicologists, and other scientific professionals.
Table of Contents
List of Contributors xv
Preface xvii
Part I Hazard Identification 1
1 Mineralogical Characteristics and Risk Assessment of Elongate Mineral Particles (EMPs): Asbestos, Fiber, and Fragment 3
Ann G. Wylie
Introduction 3
Nomenclature 6
Source Specificity: Chemical and Physical Properties 8
Source Specificity: Dimension 11
Structural Groupings of Common Elongate Minerals 13
Establishing the Chemical Composition of Minerals 15
Mineral Intergrowths and Associations 16
Bioreactivity of Mineral Surfaces: Chemical Factors 17
The Specificity of Mineral Surfaces: The Example of Quartz 17
General Considerations of Solubility 18
Formation of Reactive Oxygen Species (ROS) 20
Coatings 21
Surface Charge 22
EMP Surfaces: Chain Silicates and Zeolites 23
Physical Factors 24
Specific Surface Area 24
Enthalpy and Other Thermodynamic Properties 26
Density and Aerodynamic Diameter 26
Stiffness and Tensile Strength 28
The Effects of Heat 30
Dimensionality: General Considerations 30
Establishing Measurement Protocols 32
Optical vs. Electron Microscopy Methods 32
Stratified Counting 34
Sample Preparation for TEM: Direct vs. Indirect Preparation 34
Frequency Distributions of Length and Width 35
Lung Burden 37
Dimensionality and Carcinogenicity 38
Discussion 39
References 40
2 Toxicology of Mineral Fibers and Implications for Risk Assessment 52
Brooke T. Mossman
Introduction 52
Use of Rodent Models to Analyze the Toxicity to Disease Potential of Naturally Occurring and Synthetic Fibers 53
Inhalation Studies 53
Intratracheal Instillation and Oropharyngeal Aspiration Studies 54
Intrapleural Injection Studies 54
Intraperitoneal Injection Studies 54
Comparative Results on Effects of Asbestos and Other Naturally Occurring Fibers in Rodent Studies 54
In vitro Models of Toxicity 66
Advantages and Disadvantage of In vitro Models 66
Contributions of In vitro Models to Understanding Mechanisms of Cytotoxicity and Carcinogenesis by Mineral Fibers 67
Properties of Mineral Fibers Important in Toxicity and Carcinogenic Effects 68
A Systems Biology Approach to Understanding Connections and Interactions Between Adverse Outcomes in Mineral Fiber-Induced Diseases 71
References 72
3 Health Outcomes of Asbestos Exposure - A Pathology and Diagnostic Perspective 82
Bruce Case
Introduction 82
Nonmalignant Change in Structure or Function 83
Nonmalignant Asbestos-Related Disease 84
Pleural 84
Asbestos Effusion 84
Pleural Plaques and Localized Pleural Thickening (LPT) 84
Diffuse Pleural Thickening 88
Rounded Atelectasis 89
Lung 89
Asbestosis 89
Malignant Diseases Attributable to Asbestos Exposure 92
General Comments 92
Asbestos-Related Lung Cancer 94
Mesothelioma - Accelerating Knowledge 96
References 102
Part II Exposure Assessment 109
4 Principles of Exposure Assessment for Elongate Mineral Particles (EMPs) 111
Eric Rasmuson, James Rasmuson, and Andrey Korchevskiy
General Principles and Methods 113
Gathering Information 113
Evaluating the Quality of Data 114
Measurement Techniques 116
Comparison of the Results of Different Analytical Methodologies 120
Proximity to the Emission Source 121
Adjusting Results for Censored Data 122
Correlation of EMP Exposures and Lung Burden Analysis 122
References 123
5 Asbestos Exposure Measurements: Principles of Current and Historical Data Interpretation 127
Garry Burdett
Aim and Background 127
Causes of Asbestos-Related Lung Disease and Their Relationship to Exposure Assessment 128
Exposure Measurement 130
Historic Methods of Asbestos Exposure Measurement 131
Gravimetric Methods 131
Impaction Sampling and Microscopic Particle Counting 132
Impinger Sampling and Microscopic Particle Counting 132
Thermal Precipitator (TP) Sampling and Microscopic Particle Counting 133
Direct Reading Instruments for Particle and Fiber Counting 134
Early Sampling Strategies 135
Development of the Current Analytical Methods for Fiber Counting 136
Membrane Filter Sampling and Phase Contrast Microscopy Fiber Counting (MF-PCM) 136
Membrane Filter Sampling and Electron Microscopy (EM) Analysis 137
Limitations of Current Indices of Exposure Assessment 139
Variability of the MF-PCM Index Over Time 140
Sampling Method 140
Sample Preparation 141
Microscope Equipment and Set-Up 142
Fiber Definition 143
Counting Procedures and Performance 144
Effect of Changes to the MF-PCM Counts Over Time 145
Conclusion 146
Acknowledgements 147
References 147
6 Asbestos Exposure Modeling Using Advanced Tools Including Computational Fluid Dynamics (CFD) 153
Daniel Hall, James Rasmuson, and Cassidy Strode
Introduction 153
Validation and Application of CFD Air Dispersion Modeling 155
Overview of CFD General Methodology 157
CFD Simulation Set-Up 159
Geometry Creation and Set-Up 159
Mesh Creation 160
Parameter Set-Up 160
Computational Solve 162
Post-processing 162
Complementary Modeling Software Tools 163
Other Software Tools 164
Indoor and Outdoor Modeling Examples 164
First Example - Indoor CFD Modeling 164
Preliminary Outdoor CFD Wind Simulation - Effect on Indoor Ventilation 166
Indoor CFD Simulations 168
Mill Ventilation 168
Other Model Parameters 169
Source Descriptions 170
Reheat Furnace Brick Removal Source 170
Pipe Insulation Removal Source 171
CFD Results 172
Second Example - Outdoor CFD, AERMOD, and CALPUFF Models 174
Model Geometry 177
Receptor Descriptions 177
Source Descriptions 177
Fugitive Plant Emission - Manufacturing, Finishing, Fiber Warehouse, Tray Loading, and Stripping Station 180
Baghouse Source Emission Rates 182
Pipe Storage and Shipping Yard Source Emission Rate 183
Crusher Source Emission Rate 183
Meteorology 184
CFD Results 186
EPA Outdoor Dispersion Models 188
Geophysical Set-Up 188
CALMET Set-Up 189
CALPUFF Processor 189
CALPUFF Results 191
AERMOD Model 191
Geophysical Set-Up 191
Meteorology Set-Up 191
AERMOD Set-Up 193
AERMOD Results 194
Comparison of CFD, CALPUFF, and AERMOD Results 194
Discussion and Conclusions 194
References 197
Part III Dose-Response Assessment 201
7 Asbestos Dose-Response Assessment: The Peto Model and Its Application in the US EPA and Berman and Crump Studies 203
Andrey Korchevskiy
Rationale and Meaning of the Peto Model 203
Utilization of the Peto Model by the US EPA 212
Berman and Crump Meta-analysis Based on Peto Model 218
References 228
8 The Hodgson and Darnton Approach to Quantifying the Risks of Mesothelioma and Lung Cancer in Relation to Asbestos Exposure 233
Lucy Darnton
Introduction 233
Overview of the Hodgson and Darnton Approach 234
Metrics and Data Requirements 235
Lung Cancer 235
Mesothelioma 236
Other Data Issues 236
Summary of Cohorts Included in the Original and Updated Meta-Analyses 237
Crocidolite Cohorts 238
Amosite Cohorts 239
Other Amphiboles: Vermiculite Miners and Associated Workers, Libby, Montana, USA 241
Chrysotile Cohorts 242
Summary of Original and Updated Meta-Analyses 245
Mesothelioma 245
Lung Cancer 250
Nonlinear Exposure-Response Relationship 256
Pleural Mesothelioma 257
Peritoneal Mesothelioma 259
Lung Cancer 260
Summary 262
Application of Hodgson and Darnton for Risk Assessment 262
Conclusions 264
References 266
9 Prediction of Mesothelioma Mortality in the Context of Country-wide Risk Evaluation 270
Lucy Darnton
Conclusions 284
References 284
10 Implications of Exposure Measurement Methodologies for Dose-Response Assessment in Asbestos Worker Cohorts 286
Garry Burdett
Electron Microscopy Fiber Size Distribution for Different Cohorts and Their Relationship to PCM Fiber Counts 287
TEM Fiber-Size-Distribution in Cohorts from Mines and Mills 288
TEM Size Distributions from Manufacturing Cohorts 289
SEM Size Distributions from Manufacturing Cohorts 292
EM Determinations of Asbestos Fiber Types in Asbestos Industry Cohorts 293
Natural Occurrence 294
Mixed-Use 295
External Sources 296
Lung Burden Analysis 296
Conversions of Historic Cohort Measurement Indices to MF-PCM Fiber Counts 296
Conversion from Impinger Counts to MF-PCM 297
Conversions from Other Particle Counting Methods 299
Conversions from Gravimetric Measurement 299
Crocidolite Cohort Exposures 302
Wittenoom Occupational 302
Wittenoom Environmental 305
South African Mines and Mills 306
Massachusetts Cigarette Filter Manufacturing 309
UK Gas Mask Workers 310
Other Cohorts Exposed to Crocidolite 311
Crocidolite Summary 311
Amosite Cohort Exposures 311
South African Amosite Mining 311
Patterson, New Jersey 314
Tyler, Texas 315
Uxbridge 315
Amosite Summary 316
Chrysotile Mining and Milling Cohort Exposures 317
Quebec, Canada 318
Balangero, Italy 318
Qinghai, China 319
Uralasbest, Russia 321
Chrysotile Mining Summary 322
Chrysotile Textiles 322
South Carolina Textile Workers 324
North Carolina Textile Workers 325
Chongqing Chrysotile Cohort 327
Chrysotile Textiles Summary 328
Other Chrysotile Cohorts 328
Discussion and Outlook 330
Acknowledgement 333
References 333
11 Mathematical Modeling of Cancer Potency for Various Fibrous Minerals 344
Andrey Korchevskiy, James Rasmuson, and Eric Rasmuson
References 360
12 Theoretical and Practical Aspects of Asbestos Dose-Response Assessment 366
Andrey Korchevskiy and James Rasmuson
General Considerations and Model of Asbestos Dose-Response Assessment 366
Linear Model 367
Nonlinear Model 368
Relationship Between Different Estimation of Mesothelioma and Lung Cancer Potency Factors 371
Life Tables and Life Expectancy of the Exposed Population 374
Linearity and Nonlinearity of the Dose-Response Curves 375
Threshold and Benchmark Dose Response in Asbestos Risk Assessment 376
Community and Occupational Risk Assessment 378
Peritoneal Mesothelioma 378
Other Types of Cancer 380
Inhalation Unit Risk (IUR) for Asbestos Fibers 383
Asbestos Dose-Response and Tobacco Smoking 385
Other Factors Impacting the Dose-Response Relationship for Elongate Mineral Particles 387
References 388
Part IV Risk Characterization 393
13 Risk Characterization for Occupational and Environmental Exposure to Asbestos: Case Studies 395
James Rasmuson, Andrey Korchevskiy, and Eric Rasmuson
References 408
14 Asbestos in Soil: Risk Characterization for Occupational and Environmental Exposures 412
Andrey Korchevskiy and Robert Strode
References 424
15 Asbestos in Brakes: Risk Assessment for Exposure Patterns with Nonlinear Dynamics 427
Andrey Korchevskiy, Robert Strode, and Arseniy Korchevskiy
Ambient Air Emissions from the Brakes in Street Canyons 428
Fibers in Car Brakes: Chaotic Behavior of Emissions in a Self-regulated Community 433
Diagnosing the Chaotic Trends 439
References 441
Index 443
