Suppliers of lithopone have recognized the growing need for high-quality, reliable products that meet both industry standards and consumer preferences. They have invested in advanced production techniques and stringent quality control measures to ensure that their lithopone products deliver consistent performance. This commitment to quality allows paint formulators to achieve the desired properties in their final products, such as enhanced durability, improved hiding power, and superior color stability over time.

So, what does it all mean for you, the consumer? Should you stop eating Skittles or begin checking foods for the presence of titanium dioxide? Here's a closer look.

Nano, or ultrafine, TiO₂ comprises primary particles sized less than 100nm. In this grade, titanium dioxide is transparent (colourless) and boasts improved UV scattering and absorbing properties compared with larger particle-size pigmentary TiO₂.

A significant body of research, mostly from rodent models and in vitro studies, has linked titanium dioxide with health risks related to the gut, including intestinal inflammation, alterations to the gut microbiota, and more. It is classified by the International Agency for Research on Cancer (IARC) in Group 2B, as possibly carcinogenic to humans.

The author thanks Marco Leona, Scientist-in-Charge of the Department of Scientific Research at the Metropolitan Museum of Art for conducting fluorescence spectrometry on Wheel of Fortune and a valuable discussion of the research, as well as Silvia Centeno, Research Scientist at the Metropolitan Museum of Art, who performed Raman analysis on the watercolors and also contributed her insight. The phenomenon of the phosphorescing lithopone was originally discovered during the author's fellowship in the Sherman Fairchild Center for the Conservation of Works on Paper, funded by the Andrew W. Mellon Foundation. The author thanks all her colleagues for their ideas and support during the research of this paper, and special thanks to Rachel Mustalish for her assistance in editing this work.

However, it’s also important to note that such adverse effects depend heavily on the form of the titanium dioxide. It can come down to characteristics like “particle shape, purity, surface charge, solubility, agglomeration rate, photo-activation, etc.”

The most significant uncertainty identified by the EU experts was the concern that TiO₂ particles may have genotoxic effects. Genotoxicity refers to the ability of a chemical to directly damage genetic material within a cell (DNA), which may lead to cancer in certain situations. Although the experts did not conclude that TiO₂ particles in E171 are genotoxic, they could not rule out the concern that they might be.

Group 2B carcinogen