The FDA continues to allow for the safe use of titanium dioxide as a color additive in foods generally according to the specifications and conditions, including that the quantity of titanium dioxide does not exceed 1% by weight of the food, the FDA said in a statement to USA TODAY.

In a study published in the journal Environmental Toxicology and Pharmacology in 2020, researchers examined the effects of food additives titanium dioxide and silica on the intestinal tract by grouping and feeding mice three different food-grade particles — micro-TiO2, nano-TiO2, and nano-SiO2.  With all three groups, researchers observed changes in the gut microbiota, particularly mucus-associated bacteria. Furthermore, all three groups experienced inflammatory damage to the intestine, but the nano-TiO2 displayed the most pronounced changes. The researchers wrote: “Our results suggest that the toxic effects on the intestine were due to reduced intestinal mucus barrier function and an increase in metabolite lipopolysaccharides which activated the expression of inflammatory factors downstream. In mice exposed to nano-TiO2, the intestinal PKC/TLR4/NF-κB signaling pathway was activated. These findings will raise awareness of toxicities associated with the use of food-grade TiO2 and SiO2.”

The presence of so many lithopone factories in China has also led to advancements in production technology and quality control. Chinese manufacturers have invested heavily in research and development to improve the performance of their lithopone products, leading to higher quality and more consistent products on the market. This has helped to cement China's reputation as a leading producer of lithopone on the global stage.

Prof. Maged Younes, Chair of EFSA’s expert Panel on Food Additives and Flavourings (FAF), wrote of the decision: “Taking into account all available scientific studies and data, the Panel concluded that titanium dioxide can no longer be considered safe as a food additive. A critical element in reaching this conclusion is that we could not exclude genotoxicity concerns after consumption of titanium dioxide particles. After oral ingestion, the absorption of titanium dioxide particles is low, however they can accumulate in the body.”

While Skittles don't include white in their line-up, Dr. Johnson-Arbor theorizes that titanium dioxide is used to help contain all the other beautiful colors.