In a 2021, Chinese researchers examined the impact of E171 on lipid digestion and vitamin D3 bioaccessibility in a simulated human gastrointestinal tract model. They examined Vitamin D’s bioaccessibility, or the amount it was released in the gastrointestinal tract, becoming available for absorption, and found it “significantly decreased from 80% to 74%” with the addition of E171. In the experiment, E171 decreased lipid digestion dose-dependently. Researchers wrote: “The findings of this study enhance our understanding toward the potential impact of E171 on the nutritional attributes of foods for human digestion health.”  The study was published in the Journal of Agricultural and Food Chemistry, 

Freshwater algae show low-to-moderate susceptibility to TiO₂ exposure, with more pronounced toxic effects in the presence of UV irradiation. It has also been shown that nano-sized TiO₂ is significantly more toxic to algae Pseudokirchneriella sub-capitata than submicron-sized TiO₂. Hund-Rinke and Simon  reported that UV irradiated 25 nm TiO₂ NPs are more toxic to green freshwater algae Desmodesmus subspicatus than UV irradiated 50 nm particles, which is in agreement with Hartmann et al. UV irradiated TiO₂ NPs also inactivated other algae species such as Anabaena, Microcystis, Melsoira and Chroococcus. It was demonstrated that smaller particles have a greater potential to penetrate the cell interior than submicron-sized particles and larger aggregates. Studies have shown that the amount of TiO₂ adsorbed on algal cells can be up to 2.3 times their own weight.