While loose titanium dioxide presents a problem, titanium dioxide within sunscreen formulations presents a much safer option than conventional sunscreen chemicals like oxybenzone and octinoxate. However, titanium dioxide may become dangerous when it is nanoparticle size. Generally, nanoparticles can be 1000 times smaller than the width of a human hair. Despite nanoparticles becoming increasingly common across industries, they have not been properly assessed for human or environmental health effects, nor are they adequately regulated. Researchers don’t quite understand the impacts nanoparticles could have on human health and the environment. However, because of their infinitesimally small size, nanoparticles may be more chemically reactive and therefore more bioavailable, and may behave differently than larger particles of the same substance; these characteristics may lead to potential damage in the human body or ecosystem.

As for titanium dioxide, the FDA approved titanium dioxide for use as a food additive in 1966. The last time the agency reviewed the additive’s safety, according to the Guardian, was in 1973.

I don't see the scientific evidence in the literature that would cause people any concern, said Kaminski.

The market for anatase titanium dioxide has expanded significantly over the years, driven by growing demand from various sectors. Manufacturers are now focusing on optimizing the production processes to enhance the quality and performance of anatase TiO2. This includes advancements in synthesis methods to produce nanoparticles with improved dispersion and stability. Companies are investing in research and development to innovate new applications, particularly in the fields of renewable energy and sustainable materials.

Following the EU’s ban on E171, the FDA told the Guardian that, based on current evidence, titanium dioxide as a food additive is safe.  “The available safety studies do not demonstrate safety concerns connected to the use of titanium dioxide as a color additive.”