Exposure Assessment and Safety Considerations for Working with Engineered Nanoparticles

Preface xiii

1 Introduction 1

1.1 Why A Book on Nanotechnology Health and Safety? 1

1.2 Some Scenarios 3

1.3 Organization of the Material 5

1.4 Our Approach to Nanoparticle Health and Safety 5

References 7

2 What is a Nanoparticle? 8

2.1 Nanotechnology, Nanomaterials, and Nanoparticles 9

2.1.1 Nanotechnology 9

2.1.2 Nanomaterial 9

2.1.3 Nanoparticle 9

2.2 Naturally Occurring Nanoparticles 10

2.3 Industrial Nanoparticles 12

2.4 Engineered Nanoparticles 14

2.4.1 Carbon Nanotubes 15

2.4.2 Fullerenes 17

2.4.3 Quantum Dots 17

2.5 Emerging Uses for Engineered Nanoparticles 19

2.6 Other Useful Definitions 20

2.6.1 Aerosol 20

2.6.2 Particle Inertia 21

2.6.3 Brownian Motion 22

2.6.4 Particle Diameter 23

2.6.5 Agglomerate versus Aggregate 24

2.7 Summary 25

References 26

3 Why are we Concerned? The Unique Properties of Nanoparticles 28

3.1 Surface]to]Volume Ratio 28

3.2 Particle Size 30

3.3 Particle Concentration 32

3.4 Dose Metrics: Particle Number, Surface Area, Morphology, and Surface Properties 33

3.5 Implications for the Occupational and Environmental Health Impacts of Nanoparticles 33

3.5.1 Respiratory Deposition 33

3.5.2 Skin Penetration 34

3.6 Implications for Physical Risks 35

3.6.1 Introduction 35

3.6.2 Current Status 35

3.6.3 Conclusions 36

3.7 Summary 37

References 37

4 Routes of Exposure for Engineered Nanoparticles 39

4.1 Introduction 39

4.2 Engineered Nanoparticle Exposure through Inhalation 40

4.2.1 Human Respiratory System 40

4.2.2 Particle Deposition in the Respiratory System 43

4.3 Engineered Nanoparticle Exposure Through Dermal Contact 46

4.4 Engineered Nanoparticle Exposure Through Ingestion 48

4.5 T ranslocation of Nanoparticles from the Lung 48

4.6 Summary 49

References 49

5 Current Knowledge on the Toxicity of Nanoparticles 51

5.1 Introduction 51

5.2 The Toxicity of Industrial Nanoparticles 52

5.3 Nanoparticle Toxicity: General Concepts 53

5.3.1 Routes of Exposure 53

5.3.2 In Vivo and In Vitro Testing 53

5.4 Carbon Nanotubes 54

5.5 Fullerenes 56

5.6 Quantum Dots 58

5.7 Metal]Based Nanoparticles 58

5.8 Summary 59

References 60

6 Sources of Exposure 63

6.1 Overview of Occupational Exposures 63

6.2 Occupational Exposures in Research Facilities 64

6.3 Occupational Exposures in Manufacturing Facilities 65

6.4 Exposure Potential for ENPs in Different Physical States 66

6.4.1 Dry Powders 66

6.4.2 Liquid Suspensions 69

6.4.3 ENPs Bound to a Solid 72

6.5 Environmental Exposures to Engineered Nanoparticles 73

6.5.1 Environmental Releases 73

6.5.2 Exposures Through a Product’s Life Cycle 74

References 76

7 Evaluation of Exposures to Engineered Nanoparticles 79

7.1 Current Knowledge Concerning Exposure to Engineered

Nanoparticles 79

7.2 Exposure to Engineered Nanoparticles by Inhalation 81

7.2.1 Mass Sampling 81

7.2.2 Surface Area Measurement 83

7.2.3 Number Concentration Measurement 84

7.2.4 Conversion between Number, Surface Area, and Mass Concentrations 98

7.2.5 Particle Characterization 99

7.3 Dermal Exposures to Engineered Nanoparticles 102

7.4 Evaluation of Exposures in Aquatic Environments 104

7.4.1 Introduction 104

7.4.2 Sample Collection 104

7.4.3 Measurement Methods 105

7.4.4 Exposure Characterization in Aquatic Environments 107

References 108

8 Exposure Characterization 112

8.1 Exposure Characterization Steps 113

8.1.1 Standard Occupational Hygiene Models 113

8.1.2 Exposure Characterization for Nanomaterials 113

8.2 Exposure Measurement Strategies 120

8.2.1 Single]Location Measurement 120

8.2.2 Multiple]Location Measurement 120

8.2.3 Near]Field and Far]Field Measurement 121

8.2.4 Dynamic Personal Sampling Measurement 122

8.3 Data Analysis and Interpretation 123

8.4 Statistical Analysis of Data 124

8.4.1 Pearson Correlation 124

8.4.2 T]test 125

8.5 Practical Aspects of Aerosol Sampling and Microscopy Techniques 127

8.5.1 Aerosol Sampling Techniques 127

8.5.2 Microscopy Techniques 128

8.6 Practical Applications and Limitations 128

8.6.1 Particle Losses 128

8.6.2 Concentration Measurement versus Particle Samples 130

8.7 Typical Production Processes 130

8.7.1 Synthesis of Carbon Nanotubes 130

8.7.2 Composite Manufacture 131

8.8 Case Study: Manual Handling of Nanoparticles 133

8.8.1 Materials and Conditions 134

8.8.2 Particle Handling 134

8.8.3 Measurements 134

8.8.4 Aerosol Particle Characterization 136

8.8.5 Results 137

8.8.6 Discussion 144

8.8.7 The Challenge and Brainstorming 145

8.8.8 Study Questions 145

8.9 Case Study: Synthesis of Carbon Nanotubes 146

8.9.1 Materials and Synthesis 146

8.9.2 Measurement 147

8.9.3 Results 148

8.9.4 The Challenge and Brainstorming 155

8.9.5 Study Questions 156

8.10 Case Study: Exposure From Twin Screw Extrusion Compounding 156

8.10.1 Materials and Production Process 157

8.10.2 Measurements 158

8.10.3 Results 158

8.10.4 The Challenge and Brainstorming 162

8.10.5 Study Questions 163

References 164

9 Control of Occupational Exposures to Engineered Nanoparticles 166

9.1 Control of Airborne Exposures 166

9.1.1 General 166

9.1.2 Laboratory Fume Hoods 169

9.1.3 Alternatives to Conventional Fume Hoods 178

9.2 Control of Dermal Exposures 181

9.2.1 General 181

9.2.2 Clothing and Personal Protective Equipment 181

9.3 Administrative Controls and Good Work Practices 182

9.3.1 Housekeeping 183

9.3.2 Work Practices 183

9.3.3 Worker Training 183

9.4 Respiratory Protection 185

9.4.1 General Considerations 185

9.4.2 Respirator Designs 186

9.5 Case Study: Comparison of the Performance of Various Fume Hoods 195

9.5.1 Materials and Hoods 195

9.5.2 Measurements 198

9.5.3 Results 198

9.5.4 The Challenge and Brainstorming 206

9.5.5 Study Questions 206

9.6 Case Study: Performance of Nontraditional Fume Hoods 206

9.6.1 Materials and Hoods 207

9.6.2 Measurements 207

9.6.3 Results 207

9.6.4 The Challenge and Brainstorming 214

9.6.5 Study Questions 215

References 215

10 Control of Environmental Exposures 219

10.1 Control of Air Emissions 219

10.1.1 Factors Affecting Air Cleaner Performance 220

10.1.2 Categories of Air Cleaning Devices 220

10.2 Control of Water Emissions 228

10.3 Nanoparticles in Solid Waste 232

10.4 Control of Exposures Throughout a Product’s Life Cycle 233

10.5 Uncertainties and Needed Research 234

10.6 Case Study—Filtration Control 234

10.6.1 Materials and Process 235

10.6.2 The Challenge and Brainstorming 246

10.6.3 Study Questions 246

References 247

11 The Regulatory Environment for Engineered Nanomaterials 249

11.1 Occupational Health Regulations 250

11.1.1 Occupational Health Regulations in the European Union 250

11.1.2 US Occupational Health Regulations 252

11.1.3 Summary: Occupational Exposure Regulations 256

11.2 Environmental Regulations 257

11.2.1 US Environmental Regulations 257

11.2.2 Environmental Regulations in the European Union 261

11.3 Comparison of Nanotechnology Regulation under TSCA and REACH 263

11.3.1 The Precautionary Principle and the Burden of Proof 263

11.3.2 Differences in Handling New and Existing Chemicals 264

11.3.3 Volume]Based Thresholds and Exemptions 265

11.4 Private Law 265

11.5 Conclusions 266

References 266

12 Future Directions in Engineered Nanoparticle Health and Safety 269

12.1 Where we are Today 269

12.1.1 Research Efforts in the United States 269

12.1.2 Research Efforts in Europe 273

12.1.3 Progress toward Research Goals 273

12.2 Human Health Effects Studies 276

12.3 Exposure Assessment 276

12.3.1 Future Needs in Exposure Assessment Techniques 276

12.3.2 The Development of Occupational Exposure Limits 278

12.4 Optimal Approaches to Control Exposures 279

12.4.1 Engineering Control of Occupational Exposures 279

12.4.2 Control Banding 280

12.4.3 Respiratory Protection 280

12.4.4 Safe Work Practices 281

12.4.5 Air Pollution Control of Nanoparticles 281

12.4.6 Water Pollution Control of Nanoparticles 281

12.4.7 Nanoparticles in Waste Streams 282

12.5 The Future of Regulation 282

12.6 Conclusions 282

References 283

Index 285

Michael Ellenbecker, Emeritus Professor of Occupational and Environmental Hygiene and Director of the Toxics Use Reduction Institute at the University of Massachusetts Lowell, has published widely on the measurement and control of airborne contaminants.  He is co-author of the Wiley textbook Ventilation for Control of the Work Environment, 2d edition.  For the past ten years he has led the nanoparticle health and safety efforts at UMass Lowell. 

Candace Tsai, Assistant Professor of Occupational Health and Industrial Hygiene at Purdue University, and previously Manager for EHS research at UMass Lowell, has led groundbreaking research in exposure assessment and engineering controls associated with nanotechnology development.  She received her doctorate in occupational and environmental hygiene and cleaner production at UMass Lowell.  Dr. Tsai also has Master’s degrees in chemical engineering and management science of business administration.  Dr. Tsai has evaluated the potential for nanoparticle exposure in laboratories at many universities and  private companies, and developed control techniques and strategies to eliminate exposure in more than a dozen of them.