Titanium dioxide nanoparticles in food (additive E171): biological effects need to be confirmed
E171 is a food additive used as a colouring and made up of titanium dioxide (TiO2) particles, partially in nanometric form. A study published in January 2017 showed that chronic exposure of rats to E171 may cause precancerous colorectal lesions. ANSES received a request to assess whether this publication provided evidence to reconsider the conclusions of the European Food Safety Authority (EFSA) concerning the evaluation of E171 published in September 2016. In its conclusions, the Agency points out that although the results presented in this publication do not currently call into question EFSA’s assessment, the study does demonstrate effects that had not been identified so far, specifically potential promoting effects for carcinogenesis. As a result, the Agency highlights the need to conduct the studies required to fully characterise the potential health effects related to ingestion of the food additive E171, with a methodology and schedule to be defined.
In September 2016, the European Food Safety Authority (EFSA) published an opinion on the re-evaluation of E171, a food additive made up of titanium dioxide (TiO2) particles, on the basis of a detailed review of the literature data on TiO2 nanoparticles. This opinion concluded that current exposure of consumers to E171 related to its use in foodstuffs is not likely to constitute a health risk, but that it was not possible to establish an acceptable daily intake (ADI).
The authors of a study carried out by the French National Institute for Agricultural Research (INRA), published on 20 January 2017 and funded in the framework of the National Research Programme for Environmental and Occupational Health (PNR-EST) run by ANSES, concluded that chronic exposure of rats to titanium dioxide (additive E171) via the oral route may cause precancerous colorectal lesions. The findings do not, however, enable conclusions to be drawn on the effects of TiO2 in humans.
In view of these results, the ministries responsible for consumer affairs, health and food decided to ask ANSES to provide an opinion on dietary exposure to nanoparticles of titanium dioxide. ANSES was therefore asked to carry out a critical study of this publication to determine whether its findings alone called into question EFSA’s conclusions dating from September 2016 regarding re-evaluation of E171. The Agency was also asked, if necessary, to put forward recommendations on the priority focus areas for characterising E171 and its toxicity.
This new request is integrated into the Agency’s ongoing activities that began in October 2016 on the potential health impact of nanomaterials present in food.
The Agency’s conclusions and recommendations
Although the results of this study carried out by INRA are not sufficient to call into question the assessment of E171 undertaken by EFSA, ANSES underlines the need to conduct various studies to fully characterise the hazard associated with E171, with a methodology and schedule to be determined. This study demonstrates effects of E171 that were not identified to date, in particular potential promoting effects for carcinogenesis. These possible effects of E171, observed in relation to the colon, thus require confirmation through additional investigations.
Moreover, ANSES points to other ongoing studies, funded by the call for projects run by the Agency as part of the PNR-EST, that are soon to be published and that describe other potential effects of TiO2. These studies concern in particular the ability of TiO2 to cross the blood-brain barrier. All of these results should be examined by EFSA as part of its assessment work on food additives.
Nanomaterials and associated risks: the Agency’s recommendations
This new request follows on from the large number of studies supported by the Agency over the last few years in the area of nanomaterials and associated risks. In its opinion of 15 April 2014 regarding the assessment of risks associated with nanomaterials, ANSES drew attention to the availability of sufficient toxicological data to consider classification of various nanomaterials, including titanium dioxide, in line with the Regulation on the classification, labelling and packaging of chemical substances and mixtures (CLP).
In addition, findings concerning the development of lung tumours in the rat following inhalation or instillation of TiO2 prompted ANSES, on 20 May 2015, to submit to the European Chemicals Agency (ECHA) a proposal for the classification of titanium dioxide as a carcinogenic substance in Category 1B (substance presumed to have carcinogenic potential in humans) by inhalation, within the framework of the CLP Regulation. A decision by the ECHA is expected in the second half of 2017.
ANSES has carried out a large number of activities concerning nanomaterials since 2006, regarding food and animal feed, consumer products, and occupational exposure. The Agency points out the need to develop suitable toxicology study protocols (clear physico-chemical characterisation, detailed and reproducible protocols, etc.) and exposure studies to assess the health risks of products containing nanomaterials.
The Agency also recommends limiting exposure of workers, consumers and the environment, particularly by promoting safe products free from nanomaterials that are equivalent in terms of function, effectiveness and cost. When hazards are identified for human health or for the environment, ANSES recommends weighing the usefulness for the consumer or the general public of marketing these types of products containing nanomaterials, for which the benefits must be clearly demonstrated.
Lastly, the Agency recommends reinforcing traceability of consumer products containing nanomaterials, which is essential for risk assessment work, especially by improving the reporting process implemented within the framework of the national R-Nano portal, to ensure better description of the nanomaterials placed on the market, their specific uses, and the associated population exposures.