Titanium dioxide nanoparticles found in milk and infant formula despite food ban

Titanium dioxide (TiO₂) has been classified as a possible human carcinogen through inhalation since 2006. This nanomaterial was used as a food coloring and opacifying agent (E171) until it was banned for use in food as a precautionary measure in France in 2020 and by the European Union in 2022. However, it is still widely used in many everyday products (toothpaste, sunscreen, make-up, medications, plastic, paper, paint, etc.).

Previous studies have shown the presence of TiO₂ in surface water (lakes, rivers, ponds, canals, seas), including sources used for drinking water and to fill pools, in groundwater, in soil and in the air. The titanium dioxide particles from these sources end up alongside particles released through industrial activity, the erosion of building paint and varnishes or their use as fertilizers in the form of nanoparticles.

To better evaluate the impact on living organisms of the widespread presence of titanium dioxide in the environment and measure the real exposure of animals and humans, scientists from INRAE, AP-HP, the SOLEIL Synchrotron and CNRS studied titanium dioxide levels in human and animal milk and in infant formula. Milk serves as a proxy for maternal exposure and is an essential, irreplaceable food that newborns depend on for their healthy development.

The study is published in the journal Science of The Total Environment.

Nanoparticles detected in most milk samples

Non-destructive analyses via spectrometry conducted at the SOLEIL Synchrotron and the Lariboisière Hospital AP-HP in Paris were used to describe the titanium particle composition, calculate the total amounts of titanium, detect individual TiO₂ particles and determine their size according to the nanometric scale. Size is important because particles smaller than 100 nm are considered nanoparticles and are widely manufactured for their physicochemical properties, which are different than larger particles.

The analysis showed the presence TiO₂ nanoparticles in 100% of the animal milk samples (both organic and conventional, in fresh and powdered form, sourced from cows, donkeys and goats) and in 83% of the infant formulas (commercially produced, organic and conventional, for three different age ranges).

Titanium dioxide passes through the mammary gland

Titanium dioxide particles were detected in human milk taken from 10 volunteers living in or just outside Paris. Rates varied, with some of the women’s samples showing up to 15 times more TiO₂ than others. This shows that titanium dioxide can cross the mammary gland barrier.

Using this new analysis technique, 6 million to 3.9 billion TiO₂ particles per liter were detected in infant formula, and 16 to 348 million TiO₂ particles per liter were detected in animal milk.

Other sources of titanium

This study of contamination in milk reflects the level of exposure in newborns and mothers as well as adult milk drinkers. Previous research led by INRAE had shown that nanoparticles of titanium dioxide consumed through food during pregnancy can cross the placental barrier. This latest study shows that infants’ exposure does not end at birth: titanium particles were detected in milk despite the ban on E171 use in food, which suggests contamination through sources other than food.

Future studies could build on the characterization of titanium particles in milk for this study (size, percentage of particles smaller than 100 nm, type of Ti-bearing minerals, crystalline form) to evaluate the toxicity of combinations of particles identified depending on the species and type of milk.

Upcoming research on women in the Paris region (urban areas known for having higher levels of titanium exposure) will investigate the effects of diet and the use of cosmetics, medications and other titanium-containing products on exposure levels.