Scientists detect potential carcinogen in milk

Titanium dioxide particles, a potential human carcinogen that is banned from food, have been found in breast milk, infant formula and commercially available milk, according to research by scientists from INRAE, AP-HP and CNRS published on Wednesday, July 23, 2025.

"Widely used in a multitude of everyday products" (toothpaste, sunscreen, medicines, plastics, makeup, paper, paints, etc.) and used as a white coloring and opacifier in food (E171), titanium dioxide was banned as a precautionary measure in France in 2020 and then in the European Union in 2022, the researchers point out.

Their work, published in the journal Science of the Total Environment, shows that this compound has been detected "in human, animal and infant milk, particularly in the form of nanoparticles" .

Titanium dioxide particles were found in "the breast milk of ten female volunteers living in Paris or the nearby suburbs, at varying levels, with some women having up to 15 times more particles than others" , which proves that this substance "can pass through the mammary gland barrier" .

"100% of animal milks (fresh or powdered, from cows, donkeys or goats)" , from both organic and conventional farming, and 83% of infant milks (commercial, from 1st to 3rd age, organic or not) analyzed contained it.

In detail, 6 million to 3.9 billion titanium particles were detected per liter of infant milk , and 16 to 348 million per liter in animal milk .

"This current state of milk contamination reflects the level of exposure of newborns and mothers, but also of adult milk consumers," the researchers state. This is despite the ban on E171 in food, suggesting "the existence of contamination other than food," they emphasize.

Titanium dioxide has been classified as a potential carcinogen in humans through inhalation since 2006, according to scientists from INRAE (National Institute for Agricultural, Food and Environmental Research), AP-HP (Assistance Publique-Hôpitaux de Paris), the SOLEIL synchrotron and the CNRS, the French National Centre for Scientific Research.

The authors of this study wanted to better assess "the impact of this massive release of titanium dioxide on living beings" and "the actual exposure of animals and humans" .

It had already been shown that the nanoparticles present in the additive E171 crossed the placenta.

This work could serve as a basis for future toxicity studies.