Photgraph by Bon Appetit, Alamy
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Multi-colored layers of gelatin get their bright color from nanoparticles.

Photgraph by Bon Appetit, Alamy

Nanoparticles: Should We Be Worried?

We're ingesting them in cookies, cakes, and Jell-O, but the science is still out on what nanoparticles do to the human body.

Nanoparticles can be found in practically everything—including, it now turns out, powdered baby formula. How nervous should we be?

The fast but unsatisfying answer is that nobody yet knows.

The baby formula scare is a result of a study publicized by the Friends of the Earth which, annoyingly, doesn’t present a lot of hard data. Nanoparticles of hydroxyapatite, titanium dioxide, and silica dioxide have been identified in at least six popular brands of baby formula—but it’s not clear how many particles are present or how hazardous these particles actually are. The study zeroes in on the needle form of nano-hydoxyapatite which, at extreme magnification, looks like a creepy tangle of barbed wire.

The U.S. Food and Drug Administration recognizes hydroxyapatite, a calcium compound and a normal constituent of bones and teeth, as safe. Scientists point out that compounds on the macro scale, however, may be a whole different kettle of fish from the same compounds on the nano scale. By virtue of their small size, nanoparticles may exhibit very different properties and behaviors. Nano-hydroxyapatite, especially in its prickly-looking needle form, may be capable of doing damage to cells and tissues.

Preliminary studies have shown that nano-hydroxyapatite rapidly dissolves in the digestive tract. This means it may be a plus as a delivery mechanism for essential calcium. On the other hand, this doesn’t preclude the possibility that some nanoparticles may still enter the bloodstream and travel throughout the body, perhaps even crossing the crucial blood-brain barrier.

Just what are nanoparticles anyway?

Nanoparticles are unbelievably small, measuring some one to 100 nanometers across. Nano comes from the Greek for dwarf, a term which doesn’t begin to fill the nano-sized smallness bill. A nanometer equals a billionth of a meter. A sheet of paper is about 100,000 nanometers thick; the period at the end of this sentence is 50,000 or so nanometers across. Nanoparticles are, as satirist Douglas Adams might have said, really, really, really small.

Nanoparticles occur naturally, spewed out by volcanoes, forest fires, and other forms of combustion. We ingest untold numbers of them every time we nibble a charred marshmallow or crunch a slice of burned toast. People have been breathing or swallowing such nanoparticles for millennia.

Engineered nanoparticles—those deliberately made by us— are similarly ubiquitous. Currently we produce thousands of tons of these per year. And at a guess, will be manufacturing up to half a million annual tons by 2020. Nanoparticles are now staples of a wide range of industries and disciplines, essential components of everything from optical switches and laser diodes to solar cells, glare-blocking windshield coatings, no-iron clothing, toothpaste, sunscreen, paint, and anti-cancer drugs.

In food, as clarifiers, thickeners, and color enhancers, nanoparticles are common components of candy, cake frosting, pudding, Jell-O, yogurt, mayonnaise, and cheese. We’re all eating them. These engineered nanoparticles, however, are different in composition from their natural counterparts, and scientists don’t yet know exactly what happens when such particles interact with biological systems like our insides.

Friends of the Earth is urging the FDA to recall food products known to contain nanoparticles, enact a moratorium on new commercial nanotech products, require labeling, and conduct more rigorous and well-controlled safety studies.

At present, it’s difficult to judge what risks—if any—nanoparticles pose to human health. It’s clear that these particles may behave very differently from their macro-equivalents and it’s also likely, given their widely differing chemical compositions, that different types of nanoparticles may display varying degrees of toxicity.

In the meantime, we’ll have to wait until the research results are in.