CSPI’s Chemical Cuisine is the web’s definitive rating of the chemicals used to preserve foods and affect their taste, texture, or appearance. Besides titanium dioxide, the group recommends avoiding artificial sweeteners like aspartame, acesulfame potassium, and sucralose, as well as synthetic food dyes like Yellow 5 and Red 3. CSPI and others have recently asked the Food and Drug Administration to ban the latter dye in foods and ingested drugs because the FDA has already determined that it is a carcinogen unsafe for use in cosmetics.
The conventional surface treatment methods of titanium alloy include glow discharge plasma deposition, oxygen ion implantation, hydrogen peroxide treatment, thermal oxidation, sol-gel method, anodic oxidation, microarc oxidation, laser alloying, and pulsed laser deposition. These methods have different characteristics and are applied in different fields. Glow discharge plasma deposition can get a clean surface, and the thickness of the oxide film obtained is 2 nm to 150 nm [2–8]. The oxide film obtained from oxygen ion implantation is thicker, about several microns [9–14]. Hydrogen peroxide treatment of titanium alloy surface is a process of chemical dissolution and oxidation [15, 16]. The dense part of the oxide film is less than 5 nm [17–21]. The oxide film generated from the thermal oxidation method has a porous structure, and its thickness is commonly about 10-20 μm [22–25]. The oxide film from the sol-gel method is rich in Ti-OH, a composition that could induce apatite nucleation and improve the combining of implants and bone. It has a thickness of less than 10 μm [26–28]. Applied with the anodic oxidation method, the surface can generate a porous oxide film of 10 μm to 20 μm thickness [29–31]. Similarly, the oxide film generated from the microarc oxidation method is also porous and has a thickness of 10 μm to 20 μm [32, 33].