1 Selecting Materials for Understanding the Human Health and Ecological Risks of Nanomaterials Considerations and Approach Justin Teeguarden, PhD., DABT Pacific Northwest National Laboratory NIST Workshop September 2007

2 Workshop and Session Goals Prioritized List of Reference Nanomaterials/Characterizations Approaches for Identifying Materials Nomination of Materials Characterization Needs

3 Session 1 Introduce nanomaterial EH&S user communities Review EH&S user community activities/needs Toxicology and ecological assessment (Teeguarden) Occupational health and safety (Murashov) Environmental fate and transport (Wiesner) Candidate materials/EH&S research needs (Colvin) Present example approach UK nanomaterial reference material initiative (Hankin) Draft approach for nominating/prioritizing materials Group discussion

4 User Community Activities Human toxicology and risk assessment Fundamental research (mechanisms, QSAR,) Applied research (animal studies, modeling, risk assessment) Occupational safety and health Protection: respirator & other barrier performance Measurement methods, instrument performance and validation Environmental fate and transport Where does it go, how quickly, and how does it change during transport Aquatic, soil, and air environments Ecological effects and risk assessment Individual animal and plant toxicology Community/mesocosm studies

5 The Approach Should Consider user community needs Consider short and long term goals Consider the practical limitations of some materials

6 Common EH&S Activities Controlled exposure studies Applied and fundamental toxicology Exposure Assessment Epidemiology Occupational Ecological Assessment

7 Human Risk Assessment Research Are There Competing Goals? Applied Toxicology Determine the hazard and risk of single compounds Materials already in commerce Materials with high occupational exposure Fundamental Research Determine what drives toxicity Determine the modes of action Multiple materials with specific properties Exposure Assessment

8 Some Criteria For Selecting Materials

9 Human Exposure Commercially important materials Crucial to an industry High production volume Materials that will find new formulations every year might be poor choices High potential for human exposure Occupationally Consumer products Waste streams Breadth and magnitude of exposure

10 Potential for Environmental Release Presence in waste streams Iron particles in water treatment Intentional release Use in environmental cleanup Accidental release Consumer products washing off in lakes Nano particle fishing aids

11 Fundamental Research Will the material enable research addressing our most fundamental questions: What role does size play? Shape (spheres, rods, fibers) What physicochemical properties drive toxicity? Solubility? Charge? Reactivity? What is the mode of action? Can we develop computational models of exposure, dosimetry and response?

12 Can it be Used in Important Test Systems? Aerosols inhalation studies Liquid systems In vitro studies Ecosystems studies Dermal studies Soil Ecosystem studies

13 Other Practical Considerations Can it be reproducibly manufactured in high quantities? Is it stable over periods of up to 25 years? Oxidation Agglomeration Endotoxin contamination Can it be modified easily Gold Silica Are analytical methods sensitive enough for in vivo systems?

14 ConclusionsConclusions