The Environmental Protection Agency has awarded $4 million in grants to study the health and environmental risks posed by manufactured nanomaterials -- the new and invisibly tiny materials that are revolutionizing many industries but whose effects on living things remain largely unknown.

The grants to a dozen universities mark the first significant federal effort to assess the biological and medical implications of nanotechnology, a burgeoning field of science that is expected to become a trillion-dollar industry within the next decade.

Among the products the field has begun to make are carbon "nanotube" electrical wires, each just a few ten-thousandths the diameter of a human hair; minuscule cages of atoms that can capture pollutants in water and soil; and ultra-fine-grained catalysts that reduce manufacturers' dependence upon caustic chemicals and other pollutants.

But the strange physical and chemical traits that make these materials so valuable also have potential downsides.

Measuring three-billionths of an inch or less, they are small enough to enter the lungs and perhaps even be absorbed through the skin. Experiments in animals have shown that once in the body, they can travel to the brain and other organs.

Several experiments are already underway that involve deliberately spreading nanomaterials in the environment despite some studies suggesting they can accumulate in the food chain and kill ecologically important microorganisms.

With hundreds of tons of nanomaterials already being made in U.S. labs and factories every year -- and the release this year of several cautionary reports from European scientific organizations and insurance companies -- activists have become more vocal in their demands for safety studies.

The 12 new EPA grants, to be announced today by Paul Gilman, the agency's assistant administrator for research and development, aim to address some of those concerns.

"This emerging field has the potential to transform environmental protection, but at the same time we must understand whether nanomaterials in the environment can have an adverse impact," Gilman said in prepared remarks released last night.

The grants are a small fraction of the $3.7 billion the federal government has committed to boosting the technology over the next four years. Still, said Barbara Karn of the EPA's Office of Research and Development, "it's a lot more than has ever been done" on nanotech safety. "It is infinitely more."

Among the grants being funded:

* A study of the absorption and toxicity of nanoparticles on skin. (Several cosmetic products already contain nanoparticles.)

* A study of what happens to nanoparticles when they get into drinking water, how they interact with other pollutants there, and how toxic they are in water.

* Studies of nanoparticles' effects on cultured human lung tissues and in the airways of live animals -- including a test of whether nanoparticles cause especially severe inflammation, as some suspect.

* Studies of the environmental impacts of nanotubes that have settled into marine and freshwater sediments, and the effects of nanoparticles on aquatic bacteria, algae and plankton.

* A study of the conditions under which nanoparticles may absorb -- and perhaps later release -- environmental contaminants.

Scott Walsh, a project manager at Washington-based Environmental Defense, called the EPA grants "a great start" but decried the federal government's failure to invest more in the effort.

"Government is not yet investing enough to ensure that the risks are discovered in the laboratory instead of in our bodies, our back yards and our workplaces," Walsh said. "We're probably $90 million shy of what we need to be spending to do the job right."

The EPA is not the only federal agency looking into the safety of nanomaterials. The National Toxicology Program, a part of the National Institutes of Health, recently agreed to conduct animal studies to investigate the effects of nanoparticles in the lungs and on the skin, and their uptake and distribution into and through the body.

Other agencies, including the Occupational Safety and Health Administration and the Food and Drug Administration, have also begun to pay attention to the field.

But compared to the federal investment in nanotech's "applications," the investment in the field's "implications" remains far too small, said Hope Shand, research director for ETC Group, an Ottawa-based research and advocacy organization that has called for a moratorium on commercializing nanotech products until governments adopt stricter oversight programs.

"Hundreds of nano products are on the market today, and there is no regulatory oversight to ensure that new manufactured nanomaterials are safe for human health and the environment," Shand said. "The U.S. government is spending nearly a billion dollars per year to promote nanotech. In comparison, EPA's new funding is like a nanodrop in the bucket."

Even revelations of health effects are unlikely to derail the nano-revolution, experts said. One recent promising study, by scientists at Rice University, has shown that it is possible to redesign nanoparticles to make them less toxic. If need be, said Karn of the EPA, existing regulations guiding conventional chemicals and workplace exposures can be made more stringent for nanomaterials.

Risk is not a matter of toxicology alone but also of exposure, safeguards and other factors, Karn noted, offering the example of gasoline.

"If you drink it, it kills you. If you put it in the water, it kills fish. And yet we use it every day, and nobody would think of banning gasoline just because it's toxic."

An ant carries a 1-millimeter chip made with nanotechnology at England's University of Huddersfield.