In an article published on January 20, 2017 in the peer-reviewed journal Scientific Reports, Sarah Bettini and colleagues from Toxalim (Research Centre in Food Toxicology), University of Toulouse, France examined the effects of chronic exposure to titanium dioxide nanoparticles in rats.

Adult rats were exposed orally for up to 100 days to titanium dioxide at 10 mg/kg bw/day, a dose similar to human exposure through food consumption, as was estimated by the European Food Safety Agency (EFSA). The scientists observed for the first time that titanium dioxide can cross the intestinal barrier and relocate through the bloodstream to other parts of the body, particularly the liver. Absorption of the nanoscale fraction of titanium dioxide led to abnormal immune responses, both locally (in the intestine) and systemically (in the spleen). Moreover, at the end of the exposure period, 40% of the chronically exposed animals developed preneoplastic lesions in the colon. In the animals where lesions were deliberately induced for experimental purposes, exposure to titanium dioxide resulted in the acceleration of their progression.

A press release published by the French National Institute of Agricultural Research (INRA) on January 20, 2017 summarized that the new study showed that “chronic oral exposure to titanium dioxide plays a role in initiating and promoting the early stages of colorectal carcinogenesis,” with a reservation, however, that these findings “cannot be extrapolated to humans or more advanced stages of the disease.” Nonetheless, these new data may justify the need to perform a full carcinogenesis study to allow observations at longer exposure times and at later stages of carcinogenesis. Consequently, on January 20, 2017 three State Departments in France have officially requested that the national Agency for Food, Environmental and Occupational Health & Safety (ANSES) evaluates the health risks of titanium dioxide nanoparticles.

Titanium dioxide is a food additive (E171) widely used in diverse foodstuffs, particularly as a food color. E171 is not labeled as nanomaterial because its nanoparticle content is in the 10-40% range, whereas the labeling requires more than 50% of the material to be in the nanoparticle form. IARC has classified titanium dioxide (exposure by inhalation) as a Group 2B carcinogen, i.e. potential carcinogen in humans. In September 2016, EFSA’s Panel on Food Additives and Nutrient Sources added to Food (ANS Panel) has published its re-evaluation of safety of titanium dioxide as a food additive within the food color re-evaluation program in the EU. The experts concluded that “available data on titanium dioxide (E 171) in food do not indicate health concerns for consumers,” but recommended that “new studies be carried out to fill data gaps on possible effects on the reproductive system.” In light of the new data released this week, additional evaluation of immune system effects and cancer risk may be necessary as well.

Read more

INRA (January 20, 2017). “Food additive E171: first findings of oral exposure to titanium dioxide nanoparticles.

EFSA (September 14, 2016). “Food colours: titanium dioxide marks re-evaluation milestone.

ANS (September 14, 2016). “Scientific Opinion on the re-evaluation of titanium dioxide (E 171) as a food additive.EFSA Journal 14(9):4545.

Romain Loury (February 1, 2017). “France unveils packed 2017 environmental research programme.EurActiv

Philip Lightowlers (February 2, 2017). “Titanium dioxide in food linked to gut health effects.Chemical Watch


Bettini, S., et al. (2017). “Food-grade TiO2 impairs intestinal and systemic immune homeostasis, initiates preneoplastic lesions and promotes aberrant crypt development in the rat colon.Scientific Reports 7:40373 (published online January 20, 2017).