Nearly half of teens exposed to porn online

Many of the encounters with online pornography, both sought-out and accidental, were related to use of file-sharing programs to download images, the report from the University of New Hampshire in Durham said.

"Although there is evidence that most youth are not particularly upset when they encounter unwanted pornography on the Internet (it) could have a greater impact on some youth than voluntary encounters with pornography," the study said.

"Some youth may be psychologically and developmentally unprepared for unwanted exposure, and online images may be more graphic and extreme than pornography available from other sources," it added.

The report, published in the February issue of Pediatrics, the journal of the American Academy of Pediatrics, was based on a telephone survey made of a representative sample of 1,500 U.S. youths from March to June, 2005.

In all, 42 percent reported having been exposed to online pornography in the 12 months before they were questioned. Of that group 66 percent said they were not trying to find the material when they encountered it, which happened sometimes because of misspelled Web addresses, pop-up advertisements or spam e-mails.

The remaining third who said they sought out pornography were more likely to be teenaged boys who also used file-sharing programs to download images, talked online to strangers about sex, used the Internet at friends' homes, or possibly suffered from depression.

The researchers said sexual curiosity is normal in the teen years "and many might say that visiting X-rated Web sites is developmentally appropriate behavior." But they said some experts are worried that it could undermine social values or attitudes about sexual behavior, lead to promiscuity or compulsive and deviant behavior.

Doctors, teachers, parents and others "should assume that most boys of high school age who use the Internet have some degree of exposure to online pornography as do many girls," the study concluded.