riskscience

1. Task Group 4 Measurement MethodsMeasurement Methods for the Oral Uptake of Engineered Nanomaterials from Human Dietary SourcesApril 16, 2013 WebinarNanoRelease Food Additive 1 www.riskscience.org

2. Task Group 4 – Charges • The goals of TG4 are to: • Provide an evaluative overview of the analytical methods that are or may be useful for detection and characterization of nanoparticles in these systems, including methods under development or existing methods for conventional materials that could be modified to be used for nanoparticles • Identify conditions and types of particles for which these various methods are applicable. • Identify gaps in the methods or methods development needs with respect to measuring nanoparticles and their transitions in the alimentary tract. 2 www.riskscience.org TG4 - Measurement Methods

3. Task Group 4 - MEMBERS 3 www.riskscience.org

4. Task Group 4 – White Paper Chapters • Introduction • Overview of detection methods requirements • Detection and characterization of nanomaterial release from food contact materials • Detection, characterization and quantification of nanomaterials in foods • Detection and characterization of nanomaterials in the alimentary tract • Conclusions This presentation focuses on the main findings from the chapters above TG4 - Measurement Methods 4 www.riskscience.org

5. Chapter 1: Introduction • ‘Setting the scene’ • A critical integrative need with respect to understanding measurement needs will be to combine measurement methods with alimentary tract modeling approaches and methods. • Methods will need to incorporate particle detection and characterization methods in fluid and tissue matrices that extend to the nanoscale range. • Many of the methods to detect and measure in this size range are likely to be new or in development, however, some methods may be well established but not recognized as “nano-capable” methods. • Other methods may need modification to allow them to be useful for nanomaterial detection and characterization. TG4 - Measurement Methods 5 www.riskscience.org

6. Chapter 2: Overview of detection methods requirements • It would not be appropriate to develop experiments to study NPs in food packaging, food, or the alimentary tract if the characteristics of the starting NPs are insufficient. • Sizing of starting NPs should be accomplished with more than one method(if possible, three methods among TEM, AFM, DLS, and FFF) • Outside of sizing information, phase information can be attained with diffraction-based STEM • Confirmatory elemental information can be obtained with one of the hyphenated ICP techniques(e.g.ICP-MS) • However, both organic and inorganic pristine NP characterization is not well standardized/validated and may in and of itself be one of the areas of largest benefit from continued study TG4 - Measurement Methods 6 www.riskscience.org

7. Chapter 2: Overview of detection methods requirements • Confidence in the preliminary material measurements is a requirement before measurement attempts in more complex matrices can be trusted analytically • Comparisons can then: • relate to the original starting materials, • answer questions of whether commercial test materials are relevant to those used in foods/food packaging, • identify predictive behavior of the NPs in foods based on characteristics such as water-based or fat-based, • provide predictive properties of the NPs both after industrial processing and in food-based and alimentary tract-based temperatures and viscosities, • distinguish the consistency amongst the NP starting materials for large batches, and • differentiate natural NMs vs. deliberately added NMs. TG4 - Measurement Methods 7 www.riskscience.org

8. Chapter 2: Overview of detection methods requirements • Assuming that the NPs are well-characterized, a brief overview of current NP and/or NM-based characterization methods are presented as they may relate to food-based, food packaging-based, and alimentary tract-based complex matrices: • Compositional analysis: ‘how much is there?’ and ‘is it there at all’ ICP-MS, SP-ICP-MS, AAS, SPR, HPLC, FFF, UV-vis, surface-based techniques for aggregates. MOSTLY developed for inorganic NPs/NMs; organic relatively limited and needed • Imaging analysis: ‘where is it?’ TEM, SEM-EDS, CARS, CLSM, some MS for aggregates • Emerging methods: ‘what can we answer later that we cannot answer now?’ Microchannelresonators coupled with others above, SIMS/XPS, APT, DART, LTP, DESI, LMJ-SSP TG4 - Measurement Methods 8 www.riskscience.org

9. Some limited examples exhibited; methods in need of immediate investigation Large amount of work exhibited; methods with best chance for success or standardization Unknown ability for detection; lack of available methods for detection Isolated examples exhibited; methods of promise for future study and development Decision Tree for Choosing Measurement Methods for the Oral Uptake of Engineered Nanomaterials *Note: this decision tree is based on nanoparticle and nanomaterial analysis either in the pristine state or within simplified matrices and does not take into account differences due to nanomaterial extraction from the surrounding matrix nor the effects of the matrix on ultimate detection limits. Because of the complexities of food, food packaging, and the alimentary tract as an analytical matrix, the resulting utility of the decision tree may need to be augmented. Rather than this being a comprehensive representation of nanomaterial characterization, an emphasis was placed on what methods can yield near-term accomplishments as well as where considerable amounts of additional research are needed. 9 www.riskscience.org

10. Chapter 2: Overview of detection methods requirements • An area of community need is in the validation of the pristine NP and NM methods in terms of uncertainties, limits of detection, and potential measurement flaws – if the characterization is not quantifiable with appropriately known error ranges, it will be near impossible to make any quantitative claims for detected NPs and NMs in the more complex matrices. TG4 - Measurement Methods 10 www.riskscience.org

11. Chapter 3: Detection and characterization of nanomaterial release from food contact materials • Food contact materials include: food packaging, restaurant takeout and retail food storage containers, surfaces of food preparation (utensils, cutting boards, etc) and food processing (conveyors, nozzles, etc.) equipment, appliance linings, potable water infrastructure TG4 - Measurement Methods 11 www.riskscience.org

12. The Four “D” Nanomaterial Release Pathways TG4 - Measurement Methods 12 www.riskscience.org

13. Chapter 3: Detection and characterization of nanomaterial release from food contact materials • Inorganic ENMs have been the most heavily scrutinized materials and nanosilver products have received the greatest attention. • The dissolution of ENMs embedded within nanocomposites has not been directly studied, but some literature data imply dissolution is significant. • No studies were found that reported ENM diffusion through non-food materials into water. • It should be noted that NP environmental release data remains very limited and there is disagreement over whether existing methods to assess small molecule migration are adequate for measuring migration of nanoparticles. This deficiency hinders our ability to comprehensively assess and manage the risk associated with nanoscale materials in drinking water and food packaging areas. TG4 - Measurement Methods 13 www.riskscience.org

14. Chapter 3: Detection and characterization of nanomaterial release from food contact materials • Theoretical modeling of ENP diffusion • Methods to assess migration • Challenges • Assessment of post-release particle morphology and transformation processes • Are conventional food simulants appropriate to assess quantity and form of migrated nanoparticles? • E.g., can food simulants simulate quantity of migrated ENP, and also post-migration processes like agglomeration, dissolution, O-ripening etc. TG4 - Measurement Methods 14 www.riskscience.org

15. Chapter 4: Detection, characterization and quantification of nanomaterials in foods • Overview of flow path towards characterization and detection of nanomaterials in food TG4 - Measurement Methods 15 www.riskscience.org

16. Chapter 4: Detection, characterization and quantification of nanomaterials in foods • Most analytical techniques require sample preparation prior to injection/insertion into high-end instrumentation to quantify nanomaterials. • Examples of sample preparation methods • Digestion of food matrices liberate ENMs (e.g. acids, alkalis, enzymatic, peroxide) • Separation of ENMs from liquids by ultrafiltration or centrifugation • Solvent extraction (e.g., non-polar organics, cloud point extraction, ionic liquids) • Solid phase extraction TG4 - Measurement Methods 16 www.riskscience.org

17. Chapter 5: Detection and characterization of nanomaterials in the alimentary tract • Nanomaterials in the gut may be of exogenous and endogenous origin • There are situations when it is unclear on whether nanomaterial gets absorbed as particles or (and also) as ions • Prevailing conditions within various compartments of the alimentary tract may exert a wide spectrum of effects on passing nanoparticles • There may be low rates of nanoparticulate matter absorption in the alimentary tract TG4 - Measurement Methods 17 www.riskscience.org

18. Chapter 5: Detection and characterization of nanomaterials in the alimentary tract • Existing analytical methods for detection • in vitro gastrointestinal system. Simulate human stomach and small intestine. • Dynamic light scatter • Surface Plasmon Resonance (SPR) • Caco-2 monolayer assay TG4 - Measurement Methods 18 www.riskscience.org

19. Chapter 5: Detection and characterization of nanomaterials in the alimentary tract • Methods under development for detection • Enzyme linked immunosorbency assay (ELISA) screening kits • Existing methods that could be modified to be used for detecting nanoparticles in the alimentary canal • In vivo: Ingestion studies, tail vein blood collection, everted gut sac, fecal excretion, lymph duct cannulation • In vitro: Artificial gastrointestinal system, intestinal epithelial monolayer assay TG4 - Measurement Methods 19 www.riskscience.org

20. Chapter 5: Detection and characterization of nanomaterials in the alimentary tract • Methods for characterization of nanoparticles in the alimentary tract • Existing analytical methods for characterization Techniques have benefits and limitations (e.g., specificity, resolution, sample preparation) • Electron microscopy (EM) • Transmission Electron Microscopy (TEM) • Scanning Electron Microscopy (SEM) • Inductively Coupled Plasma Mass Spectrometry (ICP-MS) • Matrix-Assisted Laser Desorption/Ionization – Time of Flight (MALDI-TOF) Mass spectroscopy • Coherent anti-Stokes Raman scattering (CARS) microscopy TG4 - Measurement Methods 20 www.riskscience.org

21. Chapter 6: White Paper Conclusions • There is no single definitive method for characterization of nanoparticles in the alimentary tract • Analyses should not depend on only one method; instead, several complementary methods should, if possible, be used. • Coupled techniques should be further developed and increasingly applied TG4 - Measurement Methods 21 www.riskscience.org

22. On behalf of TG4 Thank you for your attention! TG4 - Measurement Methods 22 www.riskscience.org