NEW YORK (CNN/Money) - Fear is big business these days as scores of companies, large and small, have tapped the nation's heightened awareness of the threat of terrorism as a source of revenue and profits.

Previously obscure technology outfits specializing in biometric identification systems and other high-tech security products have found themselves the subject of newspaper headlines and the evening news. At the same time, a cadre of Internet entrepreneurs has emerged, hawking items such as home radiation detectors, gas masks and similar gadgets.

But the effectiveness of these items -- both in preventing and responding to a possible terrorist attack -- and the prospects for future sales remain in question.

Biometrics, a term that refers to the technology and science of using unique biological characteristics to verify a person's identity, has been around for many years. But the companies that specialize in it came sharply into focus on Wall Street shortly after Sept. 11.

Stocks of companies including Identix (IDNX: Research, Estimates), the largest publicly traded biometrics firm, and Viisage Technologies (VISG: Research, Estimates) soared to record highs following the terrorist attacks.

The attacks were carried out by radical Islamists, some of whom were on government watch lists, using four hijacked commercial airliners.

Soon after the attacks, advocates of the use of biometrics at airports suggested that a facial-recognition system -- which scans faces in a crowd and compares them against images in a database -- might have identified those hijackers who were known to the government and possibly prevented at least some of them from carrying out their plans.

RELATED STORIES       Biometric tech at Statue of Liberty Security tech firms buck downturn Identix, Visionics double up Radiation fear spurs sales, controversy Biometrics draws crowd

Several airports have begun testing such systems. But one year after the attacks, the prospects for biometrics haven't changed all that much, and stock prices of biometrics firms have fallen back.

"After 9/11, people looked and immediately said 'Biometrics is going to be a great thing,'" said Charles Kolodgy, an analyst who tracks the biometrics industry at high-tech research firm International Data Corp.

"But the people who are going to be buying this stuff are saying, 'Let's take a look at this and see what it can do for us,'" Kolodgy said. "And they're still in that process."

By IDC's estimate, sales of biometric identification devices are likely to show a 14 percent annual increase this year, then rise 15 percent in 2003.

Prior to Sept. 11, adoption of biometrics technology in the U.S. was impeded by public concerns that the government could use it to keep track of ordinary citizens' movements.

Joseph Atick, president and CEO of Identix and one of the forerunners in the development of facial-recognition technology, said many of those concerns have subsided since the Sept. 11 terrorist attacks and helped speed up the evolution of biometrics.

"Sept. 11 has pushed one important phase, which is the acceptance of the need for this kind of technology," Atick said.

Because biometrics technology ultimately can be used to address a wide range of security problems aside from the threat of terrorists -- including identity theft, computer crime and fraud -- Atick is convinced that there will be significant growth in the industry.

At the same time, he acknowledged that many of the forces that could impede its adoption -- such as legislation and government regulation and resistance by special interest groups -- remain outside the industry's control.

"That's where the risk factors are," Atick said.

Recent headlines about the threat of nuclear terrorism also have been a boon to companies selling radiation detectors, gas masks and other such items. Dozens of Web sites with names like "1-gasmasks.com," "gotgasmask.com," "nukepills.com" and "protectivesuits.com" cropped up over the past 12 months. Many of them disappeared almost as quickly as they appeared.

Jay Thompson, chief technologist of a company called Homeland Protection Inc., said sales of its home radiation detectors have been robust since they began selling earlier this summer, lifted in large part by the media's continued focus on the potential threat of nuclear terrorism.

"Every time there's some kind of story, whether it's positive or negative, there's a sales blip, and then there's a follow-on," said Thompson, one of the Los Angeles-based company's four founders.

The $149 device, called "Raditect," measures gamma radiation, the kind that would be released by a so-called "dirty bomb" as well by an explosion or a meltdown at a nuclear power plant. It sounds an alarm when radiation is detected, which the company says can give people enough time to evacuate the area, seek shelter or take other actions to protect themselves.

We don't see this as one of those quick 'scam' type products where it goes out there, people buy it, and then they stop buying it, and we move on. Jay Thompson Homeland Protection Inc.

Homeland Protection's recent advertising and marketing campaign -- which featured images of nuclear mushroom clouds juxtaposed with pictures of the flaming World Trade Center towers -- prompting criticism that the company is interested more in exploiting people's fears than in offering them any real protection.

Thompson said the company has since toned down its marketing message, backing away from the Sept. 11 imagery, and said he and his partners in the venture are in it for the long haul.

The company already has an upgraded version of the Raditect devices -- with additional features including the ability to upload the data it collects to a personal computer -- in the works, and ultimately plans to expand its product offerings, Thompson said.

A 15-minute infomercial is also currently in production and will begin airing soon, according to Thompson.

"We don't see this as one of those quick 'scam' type products where it goes out there, people buy it, and then they stop buying it, and we move on," he said. "Terrorism is here to stay."

Whether a personal radiation detector, gas mask, chemical protective suit or any other item would be effective in the event of a nuclear, biological or chemical terrorist scenario remains in question.

And some experts worry that people may equip themselves with such items and then, assuming they'll be protected, neglect to exercise an adequate amount of caution and diligence.

"My concern is that by buying these things, it's going to lull people into a false sense of security, and that people will no longer focus on what these threats really are," said Jon Wolfsthal, deputy director of the non-proliferation project at the Carnegie Endowment.

"It's sort of like a person who lives in an active hurricane area and keeps in the back of their car extra water, batteries, a full tank of gas, all the things you need in a hurricane, but then never turns on the radio to listen for when a hurricane is coming," Wolfsthal said.