Titanium dioxide (E171) is a food additive used as a whitening pigment.
Properties and uses
Titanium dioxide (TiO2) is a whitener added to a wide range of products, including paints, laundry detergents, foods, cosmetics and toothpaste. It is also used in sunblock to help protect skin from ultraviolet light. TiO2 is produced by milling natural ores. Its opacity and whiteness are highly dependent on the crystalline form and the particle size, with smaller particles, often corresponding with more potent functionality. Two crystalline forms (rutile and anatase), are approved as food colours in the EU (E171) and in the USA (up to 1% by weight of food), and as cosmetic components. Food additive approvals do not specify the particle size. The effect of particle size is a relatively new science, and small particles, e.g. nanoparticles, are difficult to define, specify and measure.
Toxicology
There is a known risk from inhaling titanium dioxide dust. In fact, dust inhalation has been classified as a suspected carcinogen by both the International Agency for Research on Cancer (IARC) and the European Chemicals Agency (EChA).
The toxic mechanism from inhaled dust depends on the crystalline form and the internalisation, i.e. particles reaching the cellular site where they will do the most damage, which is worst for smaller particles. Although this is an emerging science, with many unknowns, there is an acknowledged risk to workers in TiO2 mining. By contrast, many studies have concluded no evidence of carcinogenicity from TiO2 ingested as a food additive. There has, however, been a consistent minority conclusion that nano-particulate TiO2 does present a risk when ingested. This view was bolstered by the May 2021 change in EFSA’s Opinion to conclude that ‘E171 can no longer be considered safe as a food additive’. EFSA changed their view after taking advice from experts on nanomaterials. There is no evidence of harm, but the concern is that aggregated nanoparticles could break up once ingested. The free nanoparticles could then internalise and damage the genetic DNA.
Food Safety Regulation – recent history and potential changes
E171 is a widely used food additive in the UK and in most EU countries. In 2019 EFSA recommended that the Commission should maintain approval of E171 as a food additive, but should modify the legal specification to restrict smaller (< 100nm) particles. France went beyond this and imposed a unilateral ban on the use of TiO2 as a food additive, in January 2020. The European Parliament also took a more precautionary view and asked the Commission to ban E171 outright. Their rationale was that the additive only serves a cosmetic purpose in food, rather than a functional necessity. The May 2021 EFSA (European Food Safety Authority) Opinion, that E171 can no longer be considered safe, has made it much more likely that the Commission will accede to this request for a ban. In the UK, additives approval is the responsibility of the FSA (Food Standards Agency).
Titanium dioxide is permitted in plastics that are recycled for use as Food Contact Materials (EU FCM no. 610). There is no current move to review this approval, nor titanium dioxide’s approved use in toothpaste.
Further reading:
IFST Nanotechnology Information Statement https://www.ifst.org/resources/information-statements/nanotechnology