Titanium dioxide used for adhesive applications should contain an inorganic coating to control polarity, improve its ease of dispersion, and improve its weather resistance. The inorganic coating (zirconium dioxide, silica, alumina) is applied in the aqueous slurry by precipitation of one or more hydrated metal oxides and by neutralization of acidic and alkaline compounds.
Oman Bans Food Products Containing Titanium Dioxide, by Gulf News Report, July 23, 2023
It should also be considered that due to the low pH in the stomach, the increased dissolution of the TiO2 particles may increase its bioavailability and may facilitate the entry of titanium ions into the blood circulation. Despite the relatively large consumption of TiO2 as a food additive, no studies on the effect of pH on its absorption and bioavailability have been found in the literature. This can be attributed to a general belief that TiO2is completely insoluble. However, this is not completely true, as TiO2 particles show a certain degree of solubility.
In a small study published in the European Journal of Nutrition in 2020, researchers examined the effects of several food additives, including titanium dioxide, along with artificial sweeteners and cleaning products by testing the fecal samples of 13 people. Titanium dioxide was among the samples that “induced significant shifts in microbiome community structure.” The growth of the bacterium species belonging to C. leptum, which has been shown to decrease in patients with inflammatory bowel disease, “significantly decreased in the presence of … titanium dioxide” among other additives and sweeteners tested.
Testing samples were made mixing 100 uL of TiO2NPs suspensions (0.2 mg/mL and 0.02 mg/mL) and vitamins@P25TiO2NPs (0.2 mg/mL and 0.02 mg/mL) with 100 μL ATCC 29,213 methicillin-sensitive Staphylococcus aureus (MSSA) (107 in PBS, pH 7). Controls were made replacing nanoparticles with the same volume of PBS. The concentrations of nanoparticle suspensions were chosen based on the FDA approved maximal and the minimal amount usually found in sunscreens, which are 20% and 2% (this is equivalent to 0.2 mg/mL and 0.02 mg/mL for nanoparticles suspensions). The cream concentration, on the other hand, was an intermediate value of 10%.
