Titanium dioxide (TiO2) as a food additive: Current science report
Health Canada's Food Directorate recently completed a “state of the science” report on titanium dioxide (TiO2) as a food additive. Food-grade TiO2 is a white powder made up of small particles that has been permitted in Canada and internationally for many years as a food additive to whiten or brighten foods. Food-grade TiO2 has long been considered safe in Canada and in other countries when eaten as part of the diet.
Recent analyses of food-grade TiO2 samples have found that a significant portion of particles may be within the nanoscale. These particles (also known as nanoparticles) range in size from 1 to 100 nm, where 1 nm equals 1 billionth of a metre (the width of a typical human hair is 80,000 to 100,000 nm).
Because of their small size, nanoparticles may have unique physical and chemical properties. These properties may cause them to interact with living systems differently than larger materials with the same chemical composition (also known as bulk materials).
Food safety experts in the European Union (EU) have recently updated their safety assessment of TiO2 as a food additive. In Europe, TiO2 is referred to as E171, in accordance with European labelling requirements for food additives. The EU expert panel took into account toxicity studies of TiO2 nanoparticles, which to this point had not been considered relevant to the safety assessment of TiO2 as a food additive.
The EU expert panel did not identify an immediate health concern linked to TiO2 when used as a food additive. However, due mainly to uncertainties concerning the safety of TiO2 nanoparticles, the panel concluded that TiO2 as a food additive (E171) could no longer be considered safe.
The most significant uncertainty identified by the EU experts was the concern that TiO2 particles may have genotoxic effects. Genotoxicity refers to the ability of a chemical to directly damage genetic material within a cell (DNA), which may lead to cancer in certain situations. Although the experts did not conclude that TiO2 particles in E171 are genotoxic, they could not rule out the concern that they might be.
While the conclusions of the EU expert panel were considered in this report, Health Canada's Food Directorate conducted its own comprehensive review of the available science. This included evaluating new scientific data that addressed some of the uncertainties identified by the EU expert panel and were not available at the time of their review.
TiO2 comes in many different forms. However, only a few of these forms are considered food-grade (acceptable to be added to food). Many studies that raised concern about the safety of TiO2, including the concern for genotoxicity, used forms of TiO2 that are not considered acceptable for use in food and have different properties than food-grade TiO2. Other studies did use food-grade TiO2, but took steps to break the material down into smaller particles than what would normally be found in food.
The evidence also suggests that the toxicity of TiO2 particles may be reduced when eaten as part of the diet. This is because proteins and other molecules in a person's diet can bind to the TiO2 particles. This binding alters the physical and chemical properties of the particles, which influences how they interact with cells, tissues and organs.
A few non-dietary studies have reported adverse effects in the gastrointestinal tract of laboratory animals given food-grade TiO2. However, these same effects were not seen when the same or higher doses of food-grade TiO2 were administered in the animals' diet. Dietary studies best reflect how humans are exposed to TiO2 from food. Thus, the Food Directorate placed the most emphasis on the results of these studies in the state of the science report.
Overall, the Food Directorate's comprehensive review of the available science of TiO2 as a food additive showed:
- no evidence of cancer or other adverse effects in mice and rats exposed to high concentrations of food-grade TiO2 (long-term or lifetime study)
- no changes to DNA in various animal studies
- no adverse effects on reproduction, development, immune, gastrointestinal or nervous systems, or general health when rats were exposed from pre-conception to adulthood
In summary, the Food Directorate's position is that there is no conclusive scientific evidence that the food additive TiO2 is a concern for human health. This is based on a review of the available scientific data relevant to food uses of TiO2. However, we will continue to monitor the emerging science on the safety of TiO2 as a food additive and may revisit our position if new scientific information becomes available.
For an electronic copy of the Food Directorate's State of the Science of Titanium Dioxide (TiO2) as a Food Additive, please contact our publications office or send an email to firstname.lastname@example.org. In the subject line of your email, please write "HPFB BCS Titanium Dioxide SOS 2022-eng".
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