Nanoparticles in Foods Raise Safety Questions

It seemed like a small thing when Paul Westerhoff’s 8-year-old son appeared, with his tongue and lips coated bright white. The boy had just polished off a giant Gobstopper, a confectionery made of sugary, melt-in-the-mouth layers. Curious about the white coating, Westerhoff, an environmental engineer, pored over the jawbreaker’s contents and discovered just how incredibly small the matter was.

Among the Gobstopper’s ingredients were submicroscopic particles of titanium dioxide, a substance commonly added to plastics, paint, cosmetics and sunscreen. At the time, Westerhoff’s lab group at Arizona State University was actively tracking the fate of such particles in municipal wastewater systems across the nation.

Titanium dioxide is also a food additive approved by the U.S. Food and Drug Administration. Ground to teensy particles measuring just tens of billionths of a meter in size — much smaller than a cell or most viruses — titanium dioxide nanoparticles are frequently added to foods to whiten or brighten color.

Weeks after his son’s candy-coated encounter, Westerhoff went to the supermarket, pulled more than 100 products off the shelves and analyzed their contents. His findings, published in 2012 show that many processed foods contain titanium dioxide, much of it in the form of nanoparticles. Candies, cookies, powdered doughnuts and icing were among the products with the highest levels. Titanium dioxide is also found in cheese, cereal and Greek yogurt.

“I began to question why we care about things in the environment — at a few micrograms per liter in water — if we’re freely ingesting these materials,” Westerhoff says.

Titanium dioxide isn’t the only nanoingredient added to food. Various other materials, reduced to the nanoscale, are sprinkled into food or packaging to enhance color, flavor and freshness. A dash of nano will smooth or thicken liquids or extend the shelf life of some products. Scientists have designed nano-sized capsules to slip beneficial nutrients, such as omega-3 fish oil, into juice or mayonnaise, without the fishy taste.

Food scientists aren’t stopping there. They are downsizing the structure of a wide array of ingredients with bold plans to help tackle obesity, malnutrition and other health issues.

But as scientists cook up ways to create heart-healthy mayo and fat-fighting ice cream, some are also considering the potential risks that might accompany the would-be benefits. Because of their small size, ingested nanoparticles may interact with cells or behave differently than their bulkier counter-parts. So far, less-than-perfect laboratory studies offer contradictory results.

Researchers, including those developing nanofoods, say more information is needed on the ingredients’ potential impacts. Current studies, limited to mice or lab dishes, often analyze megadoses of particles far beyond what any normal diet would include. Scientists need a better handle on what happens when people nosh on nanolaced foods daily, taking in small doses at a time, says Ohio State University pathologist James Waldman. He and others are devising tests to find out.