(CNN) -- Some foods sold in supermarkets across America contain tiny, engineered particles called nanomaterials. Our organization decided to test doughnuts after learning that the titanium dioxide used as a coloring in the powdered sugar coating likely contained nano-sized particles.

The tests, conducted by an independent laboratory, found that both Dunkin' Donuts Powdered Cake Donuts and Hostess Donettes did indeed contain titanium dioxide nanoparticles. In response, a spokeswoman for Dunkin Donuts said the company was looking into the matter.

You must be wondering: What are nanomaterials? They are microscopic in size. "If a nanoparticle were the size of a football, a red blood cell would be the size of the field." Nanoparticles have been heralded as having the potential to revolutionize the food industry -- from enabling the production of creamy liquids that contain no fat, to enhancing flavors, improving supplement delivery, providing brighter colors, keeping food fresh longer, or indicating when it spoils.

But there are a few problems.

One is that no one knows how many and which food products have them. Companies are not being forthcoming about whether they are using nanoparticles. To further complicate the issue, some companies may not even be aware that they are selling products containing them(...)

When ingested, nano-sized particles can pass into the blood and lymph, where they circulate through the body and reach in potentially sensitive sites such as bone marrow, lymph nodes, the spleen, the brain, the liver and the heart(...)