Fear of Nanoparticles Takes the White Out of Dunkin' Donuts

Dunkin' Donuts promises to remove titanium dioxide from their powdered sugar coatings

Photo: Rachel Murray/Getty Images
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An advocacy group called As You Sow has managed to get Dunkin' Donuts to remove titanium dioxide (TiO2) from its powdered sugar formula. The move stems from fears that the TiO2 was in a nanoparticle form that had not yet been determined to be safe.

TiO2 is fairly ubiquitous in foodstuffs and is used anywhere that whiteness and opacity are desired characteristics, such as powdered sugar.  Based on this industry-wide use, it was a safe bet that some kind of TiO2 was present in Dunkin’ Donuts powdered sugar donuts.

To ensure there was no doubt, As You Sow reportedly hired an independent consultant to test the donuts for the presence of TiO2 and its use was confirmed in the tests.

The suspicion that TiO2 was in fact in nanoparticle form likely stemmed from research back in 2012 in which Paul Westerhoff and his colleagues at the University of Arizona tested random foodstuffs and personal care products and found that 5 percent of the TiO2 particles contained in the food products were less than 100 nanometers (nm) in at least one dimension.

According to Andrew Maynard, Chair of UM Department of Environmental Health Sciences and Director, University of Michigan Risk Science Center, this size of the nanoparticle is likely incidental to the manufacturing process since the ideal size for these particles from the manufacturers’ perspective is around 200 to 300 nm—the size at which the particles can most effectively do their job of reflecting and blocking light.

Whether the size of the TiO2 particles are in fact nanoscale could be seen as quibbling, but the real question is whether TiO2 nanoparticles are in fact toxic.

As Maynard explains, it is complicated. On the one hand, TiO2 particles that are ingested orally and work their way through our digestive system have thus far shown few signs of toxicity.  However, if TiO2 particles are inhaled, they can lead to pulmonary toxicity.  When the science is applied to donuts, one would hope that people are eating them and not inhaling them.

The move by As You Sow and other advocacy groups to eliminate an ingredient that has been in our food supply for generations is supported under the so-called “precautionary principle” in which producers have to take on the burden of proof regarding the level of risk of their products.

With decades of TiO2 being in our food supply and no reports of toxic reactions, it would seem that the threshold for proof is extremely high, especially when you combine the term “nano” with “asbestos”.

As You Sow makes sure to point out that asbestos is a nanoparticle. While the average diameter of an asbestos fiber is around 20 to 90 nm, their lengths varied between 200 nm and 200 micrometers.

The toxic aspect of asbestos was not its diameter, but its length. The pathogenic quality of asbestos occurs when the body's phagocytes attempt to engulf the fiber, and when unable to get around the entire length of the fiber, the phagocytes try to kill the fiber with toxic products. The attempt fails to kill the fiber but succeeds in damaging the surrounding tissue leading to mesothelioma.

It is, in fact, the longer asbestos fibers—not those nanoscale in length—that lead to the lung disease, mesothelioma. It is a bit of scare tactic to be sure to reference asbestos, but a clearly effective one.

What may turn out to be the most important part of the story is how As You Sow managed to twist Dunkin’ Donuts’ arm to get them to make the move: it was an inside job.

As You Sow’s strategy has been to introduce shareholder proposals at various companies calling for the elimination of the TiO2. At a Dunkin’ Brands’ shareholders meeting last year 19 percent of the shareholders supported a resolution to eliminate TiO2.

When asked about this method, Maynard said: “People will always find avenues to get their agenda on the table. Whatever the method, what is important is that the science is always respected. Sometimes in these efforts, it’s easy to lose sight of what the science indicates on balance.”

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IEEE Spectrum’s nanotechnology blog, featuring news and analysis about the development, applications, and future of science and technology at the nanoscale.