Plastic imbued with clay nanoparticles helps make Miller Brewing Co. beer bottles less likely to break as well as improves how long the brew lasts in storage. Simply H's Toddler Health nutritional drink mix includes 300-nanometer (300 billionths of a meter) iron particles. And a wide range of cooking and cleaning items now employ nanosize silver particles to kill microbes.

Yet, the Washington, D.C.–based environmental group Friends of the Earth (FoE) reports that none of the more than 100 food or food-related products it identified that contain nanoparticles—puny particles between 100 and one nanometers—bears a warning label or has undergone safety testing by government agencies.

"Products created using nanotechnology have entered the food chain," says report author Ian Illuminato, FoE's health and environment lobbyist. "Preliminary studies indicate there is a serious risk…. We should know that it's safe before we put it in our food."

The report builds on several studies in recent years that have shown that some nanoparticles may cause harm. A 2005 study in Environmental Science & Technology showed that zinc oxide nanoparticles were toxic to human lung cells in lab tests even at low concentrations. Other studies have shown that tiny silver particles (15 nanometers) killed liver and brain cells from rats. "They are more chemically reactive and more bioactive," Illuminato says, because of their size, which allows them to easily penetrate organs and cells. "Products should be at least labeled so consumers can choose whether they want to be part of this experiment."

FoE says it is probably underestimating the number of foods and food products containing the miniscule particles, because they depended on self-reporting by companies and a list of 600 nanotechnology products compiled by the Woodrow Wilson International Center for Scholars (a think thank created by Congress in 1968 to foster links between scholars and politicians) as part of its project to study the implications of nanotechnology.

The environmental group charged that the federal government has failed to protect consumers from the potential dangers of nanoparticles and called for a ban on their use in food and food-related products until they have been thoroughly tested to rule out health risks.

The U.S. Food and Drug Administration (FDA) currently does not specifically require nanoparticles to be proved safe but does require manufacturers to provide tests showing that the food goods employing them—be it beer or baby products—are not harmful. "Industry would bear the burden of demonstrating the safety of the material under its intended conditions of use," says FDA spokesperson Christopher Kelly. "Nanoparticle versions of [FDA-approved] materials may well be new materials" that would trigger new investigations, "and this is considered on a case-by-case basis."

To date, there are few published industry, government or scientific studies on the health and environmental impacts of nanoparticles. Further complicating the matter is the fact that nanoparticles have been in the food supply for years. "Nanoparticles have been in food products for decades, we just never realized they were there," says physicist Andrew Maynard, chief science advisor to the Wilson Center project. "We need to better understand how nano can be benign in foods, but [also] where the dangers are."

For example, it remains unclear whether nanoparticles used in food packaging might migrate or leach into food or beverages. And it is completely unknown what impact a wide variety of these nanoparticles might have on human health.

A wide variety of government agencies, including the FDA and the U.S. Environmental Protection Agency (EPA), have taken an interest in nanotechnology. The federal government spent more than $1.4 billion on nanotechnology research last year as part of the National Nanotechnology Initiative, a joint effort of 25 federal agencies investigating the promise and potential perils of the emerging technology. Of that, roughly $40 million was devoted to health and safety research (an amount set to nearly double to $76 million in the fiscal year 2009 proposed budget).

The FDA could not provide figures on how much it spends on assessing the safety of nanoparticles.

The EPA received $8.6 million of that $40 million, some $3 million of which went directly to labs to research potential health and environmental risks, according to Jim Willis, director of the EPA's Chemical Control Division.

The EPA and its counterparts in Canada, Europe, Asia and Australia also began in February a three-year study into the effects of 14 nanomaterials—including silver, iron and other elemental nanoparticles as well as carbon nanotubes and nanoballs. "Once we get the results of phase one, we'll look at moving into more in-depth testing on some of those or maybe some other nanomaterials," Willis says, adding that any new chemical submitted for approval that contains 10 percent or more nanosize elements receives special attention from EPA reviewers. "We've seen about 30 or so in the past three years," he says.

In 2006 the EPA began to regulate nanosilver as a pesticide under the Federal Insecticide, Fungicide and Rodenticide Act. As a result, companies employing such nanosilver particles (as an antimicrobial in a wide array of merchandise from computers to cooking pans) are required to register them as pesticides. Last week, the agency fined computer equipment maker IOGEAR of Irvine, Calif., $200,000 for failing to register the antimicrobial nanosilver in some of its wireless computer keyboards and mouses.

In January the agency also asked companies that use nanoparticles to begin voluntarily providing the results of any health and safety studies they had conducted. Willis says that the EPA will review company response to determine whether voluntary compliance is enough this summer.

Friends of the Earth insists that such reporting should be mandatory, given the potential risks. The lobby also says the definition of what constitutes a nanosize particle should include anything 300 nanometers or smaller. But the Wilson Center's Maynard notes it is the effect rather than the size that is significant.

"It all comes down to the need for more research. We can't fly blind here. We need to know what's going on," Maynard says. "There is no hard evidence that nanomaterials in products on the market will harm humans or the environment, but there is enough evidence to say that we need to reexamine.''