State of the Science Literature Review: Everything Nanosilver and More

Scientific, Technical, Research, Engineering and Modeling Support Final Report State of the Science Literature Review: Everything Nanosilver and More R E S E A R C H A N D D E V E L O P M E N T EPA/600/R-10/084 August 2010 www.epa.gov Scientific, Technical, Research, Engineering and Modeling Support Final Report Contract No. EP-C-05-057 Task Order No. 95 State of the Science Literature Review: Everything Nanosilver and More Prepared for Katrina Varner, Task Order Manager U.S. Environmental Protection Agency National Exposure Research Laboratory Environmental Sciences Division Las Vegas, NV Submitted by Jessica Sanford, Task Order Leader, Battelle Raghuraman Venkatapathy, Project Manager, Pegasus Prepared by Amro El-Badawy David Feldhake Raghuraman Venkatapathy Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy. Mention of trade names and commercial products does not constitute endorsement or recommendation for use. U.S. Environmental Protection Agency Office of Research and Development Washington, DC 20460 TABLE OF CONTENTS List of Figures............................................................................................................................... iii List of Tables ................................................................................................................................. v List of Abbreviations ................................................................................................................... vi Executive Summary.................................................................................................................... xii 1. Introduction............................................................................................................................... 1 2. Historical and Current Applications of Silver and Silver Nanomaterials........................... 5 2.1 Elemental Silver Characteristics and Sources....................................................................... 5 2.2 Chemistry of elemental silver ...............................................................................................5 2.3 Historical and Current Applications of Elemental Silver and Silver compounds ................ 7 2.4 Nanosilver: History and Applications................................................................................. 10 2.5 Silver Regulations in the US............................................................................................... 11 3. Uses of Silver Nanomaterials .................................................................................................14 3.1 Properties of nanosilver ...................................................................................................... 14 3.1.1 Antibacterial properties................................................................................................ 14 3.1.1.1 Antibacterial mode of action................................................................................. 15 3.1.2 Antifungal properties ................................................................................................... 16 3.1.3 Antiviral properties ...................................................................................................... 17 3.1.4 Anti-inflammatory properties ...................................................................................... 17 3.1.5 Anti-glycoprotein film properties ................................................................................ 17 3.1.6 Anti-biofilm properties ................................................................................................ 18 3.1.7 Surface plasmon resonance properties......................................................................... 18 3.1.8 Plasmonic heating properties ....................................................................................... 18 3.1.9 Metal-enhanced fluorescence properties...................................................................... 19 3.1.10 Properties of silver nanomaterials that promote its biosynthesis............................... 19 3.2 Scientific Applications........................................................................................................ 20 3.3 Industrial Applications........................................................................................................ 21 3.3.1 Catalysis....................................................................................................................... 21 3.3.2 Electronics.................................................................................................................... 22 3.3.3 Other Industrial Applications....................................................................................... 22 3.4 Applications in Consumer Products.................................................................................... 22 3.5 Medical Applications.......................................................................................................... 23 3.6 Proposed and Projected Applications ................................................................................. 24 4. Synthesis and Properties of Silver Nanomaterials............................................................... 27 4.1 Methods of Synthesis.......................................................................................................... 27 4.1.1 Synthesis Categories .................................................................................................... 27 4.1.1.1 Top-Down versus Bottom-Up............................................................................... 28 4.1.1.2 Synthesis Reactants in Bottom-Up Techniques.................................................... 30 4.1.2 General Discussion on Nanosilver Synthesis .............................................................. 32 4.2 Silver Nanocomposites and Bimetallic Nanoparticles........................................................ 35 Final Report dated 07/15/2010 i State of the Science – Everything Nanosilver and More 4.3 Environmental Perspective ................................................................................................. 35 4.4 Characteristics of the Silver Nanomaterials Products......................................................... 37 4.5 Characterization Methods, Detection and Speciation......................................................... 54 4.5.1 Methods for Measuring Ionic Silver in Nanosilver Suspensions................................. 56 4.5.2 Methods for Isolating Ionic Silver from Nanosilver Suspensions............................... 56 4.5.3 Novel Detection and Characterization Techniques for Environmental Samples......... 57 5. Potential Magnitude of Silver Nanomaterial Utilization and Environmental Exposure . 67 5.1 Inventory of Silver Nanomaterials: Industrial and consumer products .............................. 68 5.2 Routes of Release and Exposure, Ecological...................................................................... 72 5.3 Routes of Exposure, Human ............................................................................................... 77 5.3.1 Exposure via food ........................................................................................................ 80 5.3.2 Exposure via consumer products ................................................................................. 83 5.3.3 Exposure via Medical Applications............................................................................. 88 5.3.4 Exposure via occupation.............................................................................................. 92 5.4 Projected Quantities, Geographic and Demographic Distribution in the US ..................... 94 6. Toxicity and Health Effects.................................................................................................... 98 6.1 Silver Toxicity .................................................................................................................... 98 6.2 Nanosilver Toxicity .......................................................................................................... 100 6.2.1 Toxicity of Nanosilver to Organisms......................................................................... 102 6.2.2 Ecological or Multispecies Studies of Nanosilver Toxicity ...................................... 105 6.2.3 Studies Concerning Human Health Including Mammalian Models.......................... 109 6.2.3.1 Respiratory Tract Toxicity.................................................................................. 113 6.2.3.2 Neuronal Uptake ................................................................................................. 118 6.2.3.3 Dermal Toxicity.................................................................................................. 118 6.2.3.4 Gastrointestinal Tract Toxicity ........................................................................... 120 6.2.3.5 Other Organ Toxicity.......................................................................................... 121 6.2.3.5.1 Kidney Toxicity ........................................................................................... 122 6.2.3.5.2 Liver Toxicity .............................................................................................. 123 6.2.3.5.3 Immune system Toxicity.............................................................................. 123 6.2.3.5.4 Other blood effects......................................................................................

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