The appropriateness of existing methodologies to assess the

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potential risks associated with engineered and adventitious

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products of nanotechnologies

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Scientific Committee on Emerging and Newly Identified Health Risks

2005

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(SCENIHR)

TABLE OF CONTENTS

EXECUTIVE SUMMARY

1. BACKGROUND. 5

2. TERMS OF REFERENCE 7

3. SCIENTIFIC RATIONALE. 7

3.1 Introduction . 7

3.2 Definitions and Scope . 8

3.3 Nanoscience and Nanotechnology 11

3.3.1 Introduction . 11

3.3.2 Examples of Engineered Nanostructures and Materials and Their Applications .12

3.3.3 The essentials of Nanostructure Generation: Top-Down vs. Bottom-Up Chemical and Physical

Self Assembly 12

3.3.4 Nanoscale materials properties 13

3.3.5 Conclusions. . 13

3.4 Nanoparticles: Physical and Chemical Properties. 13

3.4.1 Nanoparticle - Nanoparticle Interaction. 14

3.5 Sources of Free Nanoparticles. 14

3.5.1 Formation of nanoparticles in the liquid phase 14

3.5.2 Formation of nanoparticles suspended in the gas phase. 15

3.5.3 Environmental Sources of airborne Nanoparticles. 15

3.5.4 Occupational Sources of airborne Nanoparticles . 16

3.5.5 Nanoparticles in and from Consumer Products 16

3.5.6 Conclusions . 17

3.6 The Detection and Measurement of Nanoparticles . 18

3.6.1 In situ and on-line detection principles for nanoparticles in gas suspension . 18

3.6.2 In situ and on-line detection of particles in a liquid medium. 19

3.7 The Potential for Interactions Between Nanoparticles and Living Systems. 20

3.7.1 Introduction . 20

3.7.2 Nanoparticles in Living Systems – The Surface Effects 20

3.7.3 The Effects of Size, Shape, Surface and Bulk Composition 20

3.7.4 Solubility and Persistence 21

3.7.5 Conclusions . 21

3.8 Toxicology of Nanoparticles . 22

3.8.1 The Mediators of the Toxicity of Particles. 22

3.8.2 Inhaled Particles . 24

3.8.3 Particles for Drug Delivery . 28

3.8.4 Toxicological Testing . 32

3.8.5 Conclusions . 34

3.9 Exposure Scenarios . 34

3.9.1 Sampling . 35

3.9.2 Exposure Assessment Approaches. 37

3.9.3 Conclusions . 41

3.10 Risk Assessment Methodologies. 41

3.10.1 Introduction . 41

3.10.2 General Exposure Considerations 42

3.10.3 Hazard Considerations . 44

3.10.4 Scope of Nanoparticle Risk Assessment 46

3.10.5 Exposure Assessment Methodology 48

3.10.6 Hazard Identification and Hazard Characterization Methodology 51

3.10.7 Risk Characterization and Integrated Risk Assessment . 53

3.10.8 Critical gaps in knowledge required for risk assessment purposes 54

3.10.9 Regulatory and Other Aspects Related to Risk Assessment 55

3.10.10 Other Needed Developments 55

3.10.11 Conclusions 55

3.11 Prioritisation of Needs in Knowledge . 56

4. COMMITTEE OPINION 58

5. MINORITY OPINION 62

6. REFERENCES 62

7. ACKNOWLEDGEMENTS 78