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The primary function of TiO2 in pigment production is its exceptional ability to provide brightness and opacity. When added to paints or coatings, it enhances their hiding power by reflecting light back to the observer's eye. This property not only improves the aesthetic appeal of the product but also reduces the amount of colorant needed, resulting in cost savings for manufacturers. Moreover, TiO2's high refractive index ensures that even small quantities can significantly impact the final appearance of the product.

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In a 2017 study published in Scientific Reports, researchers exposed rats to human-relevant levels of E171 to examine the effects of intestinal inflammation and carcinogenesis. They saw that “a 100-day E171 treatment promoted colon microinflammation and initiated preneoplastic lesions while also fostering the growth of aberrant crypt foci in a chemically induced carcinogenesis model.” They continued: “Stimulation of immune cells isolated from Peyer’s Patches [which are clusters of lymphoid follicles found in the intestine] showed a decrease in Thelper (Th)-1 IFN-γ secretion, while splenic Th1/Th17 inflammatory responses sharply increased,” researchers wrote. “A 100-day titanium dioxide treatment promoted colon microinflammation and initiated preneoplastic lesions.” The scientists concluded: “These data should be considered for risk assessments of the susceptibility to Th17-driven autoimmune diseases and to colorectal cancer in humans exposed to TiO2 from dietary sources.”

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