Imagine these technological marvels: drugs that seek out and destroy cancer cells, paint that changes color when viewed from different angles, molecular “ink” that encodes millions of pages of information in a square inch, and contact lenses that let you check your blood sugar by just looking in the mirror.

Those and a host of other innovations are already here, or soon will be, thanks to a scientific revolution called nanotechnology, which promises to change our world as profoundly as did electricity and the internal combustion engine.

Nanotech researchers create new materials in two main ways. They can reduce the particles in standard materials to sizes as small as a nanometer, or about one-hundred-thousandth the width of a human hair. At the nanoscale, where the ­mind-bending principles of quantum physics can apply, the characteristics of materials change: Carbon becomes 100 times stronger than steel, aluminum turns highly explosive, and gold melts at room temperature.

In addition, researchers can manipulate individual atoms and molecules, like tiny Lego pieces, to form microscopic tubes, spheres, wires, and films for specific tasks, such as generating electricity or transporting drugs in the body.

Exploiting the vast potential of those discoveries, manufacturers are bringing nanoengineered products to market at breakneck speed, spurred by a torrent of federal funding since 2001 for research and development. About $2.6 trillion worth of goods worldwide are expected to use nanotech by 2014, up from $50 billion in 2006. “Nanotechnology is creating fundamental changes in almost everything on earth,” says Mike Roco, the National Science Foundation’s senior adviser on nanotechnology, “and what we’re seeing now is just a hint of what’s to come."

But a growing number of scientists say the unique properties of nanomaterials might pose substantial risks, which are largely unexplored, to both human health and the environment. “The more we know about nanomaterials’ risks, the more we worry about what we don’t know,” says physicist Andrew Maynard, science adviser for the Project on Emerging Nanotechnologies at the Woodrow Wilson Center, a nonpartisan public-policy institute in Washington, D.C.