More than a quarter of young adults in the United States are leading a drive away from traditional wired landline telephones, cutting the cord in favour of cellphones, U.S. government research suggests.

About one in four Americans ranging in age from 18 to 24 have cellphones only, as do 29 per cent of people ages 25 through 29, according to a report by the U.S. Centers for Disease Control and Prevention (CDC) released Monday.

The ratio of U.S. adults who own cellphones and no landline grew to 12 per cent, up more than 2 percentage points in the second half of 2006.

Just 2 per cent of those 65 or older only have a cellphone.

"All those wireless adults are missed" in marketing and opinion surveys that rely on randomized phone calls to households with wired phones, said Stephen Blumberg, a senior scientist at the CDC and the report's author.

Government and private polling organizations are left unable to collect data, he said, including for health surveys.

The shift also affects the ability of 911 emergency service providers to respond to calls, because they can't track the location of the caller the way they can with a landline user.

The seriousness of the potential problem is compounded by the fact that cellphone-only users tend to be disproportionately young and have lower incomes.

According to the study, 22 per cent of the poorest adults had only cellphones — twice as many as those who are not poor.

Other findings included:

• Some 15 per cent of Hispanic adults, 13 per cent of black adults, 12 per cent of Asians and 11 per cent of whites only had cellphones.
• About 13 per cent of males and 11 percent of females only had cellphones.
• Almost 2 per cent of those polled had no phone at all.

The study was based on interviews with people in 13,056 households from June through December 2006.

With files from the Associated Press