Because of their small size, nanoparticles may have unique physical and chemical properties. These properties may cause them to interact with living systems differently than larger materials with the same chemical composition (also known as bulk materials).

Key Points/Overview

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.

Food containing titanium dioxide that is lawfully placed on the EU market before 7 August 2022 may remain on the market until its date of minimum durability or its ‘use-by’ date has passed. Food produced or placed on the market after 7 August 2022 cannot contain titanium dioxide. The ban on the use of titanium dioxide is effective in each EU Member State, and in Northern Ireland. Some third countries, such as the United Kingdom (excluding Northern Ireland), continue to permit the use of titanium dioxide.

Background