WASHINGTON (Reuters) - Nearly one in eight U.S. adults has had their credit card hijacked, identity co-opted or credit rating pockmarked by identity thieves over the past five years, the Federal Trade Commission said on Wednesday.

The crime cost U.S. businesses and consumers some $50 billion last year, but victims are getting better at limiting the damage, the FTC said.

Scam artists have used others' identities to take out loans and provide an alibi to police for decades, but identity theft has become much more common in recent years.

The consumer-protection agency has tracked identity-theft since 1998, but exact figures have been hard to come by as many victims never report the crime to criminal authorities, opting instead to work with banks or other businesses to clear their names.

The FTC surveyed some 4,000 adults this spring to come up with the most comprehensive picture yet of the fast-growing crime.

Amid the grim statistics, the agency found a silver lining: After nearly doubling for two to three years, new incidents of identity theft are growing more slowly and tend to involve less money. That's because banks are wising up to the problem, making it more difficult for scam artists to set up fraudulent credit cards, and consumers are spotting suspicious activity on their accounts earlier, said Howard Beales, director of the FTC's consumer-protection division.

"Consumers are learning to look for signs of trouble," Beales said, noting that one-third of victims surveyed said they noticed suspicious activity within a week. "Education, outreach and media reports are helping consumers to wise up."

Businesses have become more sensitive to consumers' privacy as well, limiting the disclosure of account numbers and other sensitive information, he said.

Because consumers are not liable for charges they did not incur, businesses bear the brunt of identity-theft costs. Still, some 38 percent of victims surveyed said they never told anyone about their problem and simply swallowed the charges.

Beales said those who discover unauthorized charges on their credit cards or other signs of identity theft should call the FTC's hotline at 1-877-ID-THEFT (1-877-438-4338), or log on to (http://www.consumer.gov/idtheft).