ORLANDO (FLORIDA): Those consumers already worried about genetically engineered or cloned food reaching their tables may soon find something else in their grocery carts to furrow their brows over - nano-foods. Consumer advocates taking part in a food safety conference in Orlando, Florida, this week said food produced by using nanotechnology is quietly coming onto the market, and they want US authorities to force manufacturers to identify them. Nanotechnology involves the design and manipulation of materials on molecular scales, smaller than the width of a human hair and invisible to the naked eye. Companies using nanotechnology say it can enhance the flavor or nutritional effectiveness of food. US health officials generally prefer not to place warning labels on products unless there are clear reasons for caution or concern. But consumer advocates say uncertainty over health consequences alone is sufficient cause to justify identifying nano-foods. "I think nanotechnology is the new genetic engineering. People just don't know what's going on, and it's moving so fast,"Jane Kolodinsky, a consumer economist at the University of Vermont, said at the conference. American consumers are generally more complacent about genetically modified or cloned foods than their counterparts in Europe. But Michael Hansen, a senior scientist with the Consumers Union, said polls show that 69% of Americans are concerned about eating cloned meat. He said that in focus groups run by the US Food and Drug Administration, no parents were willing to feed their children meat from cloned animals or their offspring. New consumer products created through nanotechnology are coming on the market at the rate of 3 to 4 per week, according to an advocacy group, The Project on Emerging Nanotechnologies (PEN), based on an inventory it has drawn up of 609 known or claimed nano-products. Nano-products in common use today include lightweight tennis rackets and bicycles, and sunscreens containing clear, nonwhite versions of zinc oxide and titanium dioxide. On PEN's list are three foods - a brand of canola cooking oil called Canola Active Oil, a tea called Nanotea and a chocolate diet shake called Nanoceuticals Slim Shake Chocolate.