Comparing pornography to heroin, researchers on Thursday called on Congress to finance studies on "porn addiction" and launch a public health campaign about the dangers.

"We're so afraid to talk about sex in our society that we really give carte blanche to the people who are producing this kind of material," said James B. Weaver, a Virginia Tech professor who studies the impact of pornography.

Internet pornography is corrupting children and hooking adults into an addiction that threatens their jobs and families, a panel of anti-porn advocates told the hearing organized by Sen. Sam Brownback, R-Kan., chairman of the Commerce subcommittee on science.

Brownback, a father of five, said when he was a boy, the typical kid's exposure was limited to occasional peeks at dirty magazines illicitly obtained by a buddy.

Now, he said, pornography seems pervasive. Children run across it while researching homework on the Internet. Vulgar ads arrive unexpectedly by e-mail. Some of his middle-age male friends limit their time alone in hotel rooms to avoid the temptation of graphic pay-per-view movies, Brownback said.

Mary Anne Layden, co-director of a sexual trauma program at the University of Pennsylvania, said pornography's effect on the brain mirrors addiction to heroin or crack cocaine. She told of one patient, a business executive, who arrived at his office at 9 a.m. each day, logged onto Internet porn sites, and didn't log off until 5 p.m.

Layden called for billboards and bus ads warning people to avoid pornography, strip clubs and prostitutes.

The panel discussion ranged from hardcore, violent pornography to audience complaints about a sexually suggestive promo that aired prior to this week's "Monday Night Football" game.

Brownback, an outspoken Christian conservative who has championed efforts to curb indecency on television and the Internet, said the public is beginning to realize "they don't just have to take it."

But he acknowledged the First Amendment right to free speech has limited congressional efforts.

In June, the Supreme Court blocked a law designed to shield Web-surfing children from pornography, ruling that requiring adults to register or use access codes before viewing objectionable material would infringe on their rights.

Brownback said scientific data is needed to help his cause.

Weaver acknowledged that research "directly assessing the impact of pornography addiction on families and communities is rather limited."

But he pointed to studies that show prolonged use of pornography leads to "sexual callousness, the erosion of family values and diminished sexual satisfaction."

Judith Reisman, a vocal critic of the Kinsey Institute and the field of sexology, suggested Congress require police officers to gather evidence of pornography at crime scenes to further research.