Characterization of Food Grade Titanium Dioxide

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1 Characterization of Food Grade Titanium Dioxide Paul Westerhoff Yu Yang, Kyle Doudrick, Pierre Herckes, Kiril Hristovski, James Bo Faust and David Capco Arizona State University Tempe, AZ Funding was provided from NSF (CBET )

2 Nanoparticles in our food Magically Disappears?

3 Titanium Conc (mg Ti/mg food) Titanium content of foods Weir et al., ES&T (2012)

4 TiO2 from Candy Coating on Chewing Gum

5 Multi-phase products have un-even TiO2 distribution

6 Human exposures to Nano is real

7 But is there hazard?

8 Faust et al. (in prep) A B Gum

after TiO2 in gum 50 40 * 30 1µg/cm 2 gum 2 10µg/cm 2 gum 2 E

9 Microvilli (number/square µm2) A B Microvilli of Caco-2 Cells Untreated C 2 µm 100ng/cm 2 gum 2 D µm Number of Microvilli after TiO2 in gum * 30 1µg/cm 2 gum 2 10µg/cm 2 gum 2 E µm µm * * Faust et al. (in prep) Treatment 100ng/cm 2 gum 5 µm

10 Strategies for Assessing Nanoparticles Test thousands of products in our Food Supply Go to suppliers instead of products Make nutritional food baskets and screen for nanoparticles E171 is food grade TiO2

11 Source of TiO 2 Powders Four types of food grade titanium dioxide powders were purchased from four manufactures in China, which were named sample 1, 2, 3, and 4. A fifth sample was obtained from Europe, E171, is a European Union designation for a white food color additive. A non-food TiO 2 sample used as a catalyst was also characterized (P25)

12 Size Determined by TEM Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Averaged Samples Diameter (nm) #1 120 ± 46 #2 130 ± 43 #3 144 ± 37 # ± 47 # ± 54

13 E171 versus P25 - E171 is food-grade color additive - Contains a distribution of sizes ( nm average) - EASILY dispersed in water - P25 is a catalyst or catalyst support - Individual NPs < 100 nm - NOT EASILY dispersed in water

14 Number (%) Number (%) Number (%) Number (%) Number (%) Number (%) Size distributions by TEM vs DLS 40 Sample 1 30 Sample 2 50 Sample Diameters (nm) Diameters (nm) Diameters (nm) 30 Sample 1 30 Sample 2 30 Sample Particle size (nm) Particle size (nm) 0 Particle size (nm)

15 Number (%) Number (%) Number (%) Number (%) Size distributions by TEM vs DLS 50 Sample 4 60 Sample Diameters (nm) Diameters (nm) 50 Sample 4 40 Sample Particle size (nm) 0 Particle size (nm)

16 Summary of Food Grade TiO 2 Sizes By TEM (n=100 particles), Samples ± 38, 122 ± 48, 132 ± 56, 124 ± 42, and 117 ± 41 nm 35%, 23%, 21%, 17%, and 19% TiO 2 particles < 100 nm in the longest dimension By ZetaPALS in DI water: Mean hydrodynamic sizes : 273, 405, 209, 504, and 127 nm All samples detected some particles < 100 nm

17 X-ray Diffraction (XRD) of Food Grade TiO 2 Sample 4

18 Absorbance (a.u.) Ultraviolet visible light diffuse reflectance(uv/vis DR) absorbance spectrum Sample 1 Sample 2 Sample 3 Sample 4 Sample Wavelength (λ)

19 What is on the surface of the TiO 2?

20 X-ray Photoelectron Spectroscopy O 1s spectra of Sample 1-5. (1) phosphate, (2) titanium dioxide (3) silica (4) carbonyl (5) alumina Sample 4 showed different bindings on the surface.

21 Acid digested of TiO 2 (P or Al/Si are on surface) Sample TiO 2 (wt%) Al (wt%) Si (wt%) P (wt%) ± ± ± ± ± ± ± ± ± ± ± ± ± 0.81 ± ± ± ± ± ± ± 0.00

22 P in TiO2 Powder (mg/g) Phosphorous release into water Total P from added TiO2 Soluble P released into solution Ortho-P released into solution Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Soluble - P Ortho- P Total -P The total phosphorous in P25 is below detection limit (0.1 mg/g).

23 Zeta potential (mv) P on TiO 2 decreases Zeta Potential 40 Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 P ph

24 Zeta Potential (mv) Phosphate added to TiO2 solutions impact Zeta Potential P25 P µg P/ mg Ti P µg P/ mg Ti

25 Final Thoughts & Practical Questions Food grade TiO 2 ( (E171) was quite uniform across different suppliers E171 differs dramatically from P25 Roughly 30% of particles in E171 had primary particle sizes < 100 nm E171 contained mostly anatase; 1 had rutile E171 should be photo-active below 400 nm Phosphates are dominant coatings on E171, with one having Al & Si Some phosphate desorbs from E171 when added to water, but some remains surface bound too Analyzing food grade TiO2 gave similar findings as analyzing > 100 food products & suggests this as a good path forward to characterize real world nanoparticles

26 Can I put a donut in your TEM instrument? Or Other Questions

27 Test thousands of products? Go to suppliers instead of products Make nutritional food baskets and screen for nanoparticles E171 is food grade TiO2

28 Neutrogena Senstive Skin Sunblock Neutrogena Pure and Free Baby Solar Sense Zany Zinc Sensedyne Aquafresh Colgate (Small) Topol Ultrabrite Crest Mint Stripe Crest Cool Mint Colgate (Large) Ocean Potion Face Potion Aveeno Continuous Protection Neutrogena Ultra Sheer Sunblock Coppertone Sunscreen Lotion Hawaiian Touch Sheer Touch Solar Essentials SPF 50 Baby Head and Shoulders 2 in 1 Shampoo Coppertone Water Babies Bull Frog Quick Spray Sunblock Ocean Potion Sunblock Head and Shoulders Classic Clean Coppertone Water Babies Sunscreen Gillette Foamy Regular Pantene Classic Shampoo Banana Boat Sunscreen Lip Balm Suave Green Apple Conditioner Suave Conconut Conditioner Pantene Flat to Volume Conditioner Arm & Hammer Ultra Max Dove Powder Old Spice High Endurance Sunscreens, Toothpaste, and Personal Care Products contain Ti Normalized (ugti /mg) Orange: Sunscreen with Ti listed on label Red: Toothpaste with Ti listed on label Weir et al., ES&T (2012)

TiO 2. : Manufacture of Titanium Dioxide. www.rsc.org/learn-chemistry Registered charity number 207890

TiO 2. : Manufacture of Titanium Dioxide. www.rsc.org/learn-chemistry Registered charity number 207890 TiO 2 : Manufacture of Titanium Dioxide www.rsc.org/learn-chemistry Registered charity number 207890 5: Manufacture of titanium dioxide Titanium dioxide has many uses. It is now the common white pigment