Unbeknownst to just about everyone, nanoparticles made a quiet entrance into the nation’s food supply at least a decade ago. Nanoparticles are materials that are microscopic—significantly smaller than a red blood cell; and tens of thousands of times smaller than the width of a human hair. These particles can help deliver nutrients, ensure longer freshness of food, act as thickening agents or enhance taste or flavor. The problem is, scientists are still determining the health and environmental impact of these tiny particles, even as industry is forging ahead.

“At the moment, there is not much information available on the topic of ingested nanoparticles and human health,” says Birgit Gaiser, Ph.D., a postdoctoral research fellow at Heriot-Watt University in the UK. “Some nanoparticles are present in the human diet, for example titanium dioxide in food products and cosmetics, and silver, which is sold as a nutritional supplement. There is evidence that a small percentage of these particles…can move on from the intestinal tract into the blood, and reach other organs.”

The U.S. Food & Drug Administration (FDA) has been slow to catch up. In fact, the agency doesn’t even track which foods contain nanoparticles. When Sebastian Cianci, a spokesperson at the FDA, was asked about the prevalence of nanomaterials in our food supply he responded: “FDA does not have a list of food products that contain nanomaterials,” and added that he could “not reliably answer” where in food products such nanomaterials are most often found.

Now With Extra Nano

There is no doubt that nanoparticles are in the food supply and have been for years. Recent research found that foods with caramelized sugar, including bread and corn flakes, contain carbon nanoparticles. Many nutritional supplements—or “nanoceuticals”—come equipped with copper, silver or iron nanoparticles. Nanoparticles can be used to purify water, as anticaking and gelatin-forming agents and in packaging to protect against UV light, prevent the growth of microbes or detect contamination. Titanium dioxide lends white pigment to most toothpastes and many processed foods, including Mentos, Trident and Dentyne gum, M&Ms and Betty Crocker Whipped Cream Frosting. The aforementioned products were featured in a report in February 2012 in the journal Environmental Science & Technology which concluded that each of us likely consumes some amount of titanium dioxide (TiO2) nanoparticles each day, and children under 10 likely consume the greatest amounts (around 1-2 mg TiO2 per kilogram body weight per day) due to their higher intake of frosted foods, candy, gum and other sweets.

Then there are the nanoparticles that slip through wastewater treatment in particle or dissolved form and take up residence in the biosolids created at the end of the wastewater treatment process. These biosolids are later applied to fields as fertilizer. In August 2012, a team of researchers discovered that soybean plants absorbed zinc oxide nanoparticles from sunscreens, cosmetics and lotions. It was certain these particles were entering the food supply, but unclear what impact they might be having.

Dietary exposure to nanoparticles is also happening through food packaging. There is nanoclay, used in some beverage containers; nanoaluminum, used in aluminum foil; and nanosilver, used in some food containers. “Nanosilver releases ions, so those ions could be getting into the food,” says Jennifer Sass, a senior scientist with the Natural Resources Defense Council (NRDC). “The ions are toxic, they are the antimicrobial part of the silver.”

From the government’s perspective, nano forms of silver, iron or titanium are no different, fundamentally, from their scaled-up counterparts which have already been safety tested, so the agency has ushered the particles into the food supply under the Generally Recognized as Safe provision. But as the environmental organization Friends of the Earth notes on their website: “The physical and chemical properties of nanoparticles,” including toxicity, “can…be quite different from those of larger particles of the same substance.”

The FDA issued a draft guidance for manufacturers in the food industry in April 2012 advising them to consider where using nanotechnology will affect the identity or safety of the food substance, which could lead to an acknowledgment on the product label, but only at the manufacturer’s discretion.

Companies, Consumers Left Clueless

In many cases, companies don’t know if their food packaging contains nanomaterials. The organization As You Sow released a report in 2011 in which they interviewed five food giants—Kraft Foods, Yum! Brands, Pepsico, McDonald’s and Whole Foods—in hopes to learn how these companies were using or planning to use nanomaterials. As You Sow’s Senior Strategist Michael Passoff says: “They had to go back to their supply chains and check. It’s hard for the companies to know. The manufacturers of nanofood or nanopackaging are not required to identify it anywhere.”

The Woodrow Wilson International Center for Scholars’ Project on Emerging Nanotechnologies may be the only place trying to keep tabs on which products contain nanomaterials, but its 1,000-plus manufacturer-identified inventory is woefully incomplete, particularly when it comes to food, where just five products are listed.

Unknown Health Consequences

While the government remains hands off, consumer health and environmental groups are warning of the mounting evidence suggesting that nanoparticles, because of their small size, can cause harm when inhaled or ingested. In 2011, researchers discovered that silver nanoparticles, when inhaled, cause lung toxicity or inflammation in exposed mice. Carbon nanotubes, used in super-strong plastics and for computer chips, can damage lungs much like asbestos, which the particles resemble in shape and size.

And ingestion, like inhalation, can carry nanoparticles into the bloodstream. A guide on the American Society of Safety Engineers’ website reports that “Nanoparticles may…accumulate in certain organs, disrupt and impair biological, structural and metabolic processes and weaken the immune system.”

Some of the impacts of chronic exposure to nanoparticles appear to be more subtle. A Cornell research team led by Gretchen Mahler, Ph.D., found that when chickens consumed large doses of polystyrene nanoparticles, approved for human consumption, it had two opposite effects. When exposure was acute, it blocked the animals’ ability to absorb iron. When exposure was chronic, it resulted in increased intestinal villi and an increased rate of iron absorption. “Nanoparticle exposure…can have unintended physiological consequences,” Mahler says. “The human response, especially the more subtle effects related to chronic exposure, is not always known.”

And each nanomaterial is unique in the way it interacts with the human body. For this reason, an article in the Journal of Nanobiotechnology cautions that “For those nanoparticles designed to stabilize food or to deliver drug via intestinal uptake other, more demanding, rules exist and should be followed…”

Approach with Caution

In the absence of specific regulations, the onus remains on food producers to identify nanomaterials in their product lines and keep the public informed with clear labeling. A 2011 report from As You Sow provides companies with a series of steps they can take to achieve transparency.

At the NRDC, Sass suggests that the FDA needs to take regulation more seriously. The Safe Chemicals Act, which passed the Senate Committee on the Environment and Public Works in July 2012 and would insist on mandatory safety testing for all approved chemicals, would be, she notes, an important first step. The law would provide some method of controlling the spread of the most suspect nanoparticles. “We’re just trying to get them [nanoparticles] to be considered as unique from conventional, to be regulated better,” says Sass.

The original version of this article first appeared in E-The Environmental Magazine and has been reprinted with permission.