Scientific, Technical, Research, Engineering and Modeling Support (STREAMS) Final Report State of the Science Literature Review: Nano Titanium Dioxide Environmental Matters 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-10/089 August 2010 www.epa.gov Scientific, Technical, Research, Engineering and Modeling Support (STREAMS) Final Report Contract No. EP-C-05-059 Task Order No. 94 State of the Science Literature Review: Nano Titanium Dioxide Environmental Matters Prepared for Katrina Varner, Task Order Manager U.S. Environmental Protection Agency National Exposure Research Laboratory Environmental Sciences Division Las Vegas, NV 89119 Prepared by Eastern Research Group 10200 Alliance Road, Suite 190 Cincinnati, OH 45242 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 CONTENTS Page 1. EXECUTIVE SUMMARY......................................................................................................1-1 2. PURPOSE OF REPORT.........................................................................................................2-1 3. LITERATURE AND GRAY INFORMATION SEARCH STRATEGY.............................................3-1 3.1 Dialog® Search Strategy and Results..................................................................3-1 3.1.1 Dialog® Search Parameters.....................................................................3-2 3.1.2 Dialog® Search Procedure and Results...................................................3-4 3.2 Targeted Search of Databases, Journals, and Conference Proceedings and Results..................................................................................................................3-7 3.2.1 Nano-specific Journals.............................................................................3-7 3.2.2 Conference Proceedings...........................................................................3-7 3.2.3 Databases of Nanotechnology Research..................................................3-8 3.3 Contacts with Industry and Academic Experts....................................................3-9 3.4 Results and Areas for Future Work ...................................................................3-10 4. BACKGROUND OF TITANIUM DIOXIDE AND ITS USE ..........................................................4-1 4.1 Titanium Dioxide Physical and Chemical Properties ..........................................4-1 4.2 Overview of Applications of Titanium Dioxide ..................................................4-2 4.2.1 Historical Applications of Titanium Dioxide ..........................................4-2 4.2.2 Applications of Nanoscale Titanium Dioxide..........................................4-4 5. LIFE CYCLE OVERVIEW ....................................................................................................5-1 5.1 Manufacture of Nano-TiO2 ..................................................................................5-3 5.1.1 Manufacture of Nano-TiO2 for Sunscreens ...........................................5-10 5.1.2 Manufacture of Nano-TiO2 for Other UV Stabilizers............................5-11 5.1.3 Manufacture of Nano-TiO2 for Photocatalysts ......................................5-11 5.2 Processing of Nano-TiO2 ...................................................................................5-11 5.2.1 Processing of Nano-TiO2 for Sunscreens ..............................................5-12 5.2.2 Processing of Nano-TiO2 for Other UV Stabilizers...............................5-12 5.2.3 Processing of Nano-TiO2 for Photocatalysts .........................................5-13 5.3 Use of Nano-TiO2 ..............................................................................................5-13 5.3.1 Use of Nano-TiO2 in Sunscreens ...........................................................5-13 5.3.2 Use of Nano-TiO2 as Other UV Stabilizers ...........................................5-14 5.3.3 Use of Nano-TiO2 as Photocatalysts......................................................5-14 5.4 End of Life .........................................................................................................5-15 5.4.1 End-of-Life of Sunscreens .....................................................................5-15 5.4.2 End-of-Life of Other UV Stabilizers .....................................................5-16 5.4.3 End-of-Life of Photocatalysts................................................................5-16 6. EXPOSURE PATHWAYS......................................................................................................6-1 6.1 Exposure Sources.................................................................................................6-1 6.1.1 Manufacturing..........................................................................................6-1 6.1.2 Processing ................................................................................................6-3 6.1.3 Use ...........................................................................................................6-4 6.1.4 End-of-Life of Consumer Products..........................................................6-6 i CONTENTS (Continued) Page 6.2 Transport Mechanisms.........................................................................................6-8 6.2.1 Transport Mechanisms in Surface Water.................................................6-8 6.2.2 Transport Mechanisms in Groundwater...................................................6-9 6.2.3 Transport Mechanisms in Soil ...............................................................6-10 6.2.4 Transport Mechanisms in Air ................................................................6-11 6.3 Points and Routes of Exposure ..........................................................................6-11 6.3.1 Dermal Exposures..................................................................................6-11 6.3.2 Inhalation Exposures..............................................................................6-11 6.3.3 Ingestion Exposures...............................................................................6-11 6.4 Receptor Populations .........................................................................................6-12 7. TOXIC EFFECTS.................................................................................................................7-1 7.1 Health Effects.......................................................................................................7-1 7.1.1 Inhalation Studies or Effects....................................................................7-3 7.1.2 Dermal Studies or Effects ........................................................................7-4 7.1.3 Oral Administration Studies or Effects....................................................7-4 7.2 Ecological Effects ................................................................................................7-4 7.2.1 Aquatic Life .............................................................................................7-4 7.2.2 Terrestrial Life .........................................................................................7-5 7.3 Additional Literature............................................................................................7-5 8. SAMPLING AND ANALYSIS ................................................................................................8-1 8.1 Sampling Techniques...........................................................................................8-1 8.1.1 Sampling Techniques Suited for Surface Waters ....................................8-2 8.1.2 Sampling Techniques Suited for Sediments ............................................8-2 8.1.3 Sampling Techniques Suited for Soil ......................................................8-3 8.1.4 Sampling Techniques Suited for Groundwater........................................8-3 8.1.5 Sampling Techniques Suited for Air........................................................8-3 8.2 Analytical Techniques .........................................................................................8-3 8.2.1 Analytical Techniques for Size Fractionation..........................................8-4 8.2.2 Analytical Techniques for Size Distribution............................................8-5 8.2.3 Analytical Techniques for Surface Area..................................................8-8 8.2.4 Analytical Techniques for Chemical Analysis ........................................8-8 8.2.5 Analytical Techniques for Direct Visualization ......................................8-8 8.2.6 Analytical Techniques for Mineral Phase/Internal Structure...................8-9 9. REFERENCES .....................................................................................................................9-1 APPENDIX A DIALOG® SEARCH RESULTS A-1 Potentially Applicable Titles for Production, Use, Distribution, and Disposal of Nano-TiO2 A-2 Potentially Applicable Titles for Exposure Pathways and Transport Mechanisms A-3 Potentially Applicable Titles for Toxicological and Ecological Effects of Nano­ TiO2 A-4 Potentially Applicable Titles for Sampling and Analysis of Nano-TiO2 in the Environment ii CONTENTS (Continued) Page A-5 Non-applicable Titles iii LIST OF TABLES Page Table 3-1.