Miley Cyrus, who plays the Hanna Montana character on Disney's wildly successful kids' program, set off a firestorm of parental protest over the weekend when suggestive poses of the 15-year old actress appeared in a magazine and quickly made their way to the Internet.

Gigi Durham, author of the new book "The Lolita Effect," says it's all part of a long-running trend to sexualize 'tween girls - those between the ages of 8 and 12 in order to create cradle-to-grave consumers.

The Cyrus photos, shot by celebrity photographer Annie Liebowitz, might seem tame by today's celebrity photo standards, but parents point out that Cyrus is a role model to impressionable young girls. Then, there's also the fact that Cyrus herself is only 15. Durham says it fits into a troubling trend.

At Abercrombie & Fitch, little girls were sold thong underwear tagged with the phrases "eye candy" and "wink wink." In Britain, preschoolers could learn to strip with their very own Peekaboo Pole-Dancing Kits -- complete with kiddie garter belts and play money. And 'tween readers of the magazine Seventeen discovered "405 ways to look hot" like Paris Hilton.

"A lot of very sexual products are being marketed to very young kids," said Durham. "I'm criticizing the unhealthy and damaging representations of girls' sexuality, and how the media present girls' sexuality in a way that's tied to their profit motives. The body ideals presented in the media are virtually impossible to attain, but girls don't always realize that, and they'll buy an awful lot of products to try to achieve those bodies. There's endless consumerism built around that."

Durham advocates healthy and progressive concepts of girls' sexuality, but criticizes the media for its sexual representations. She says studies by the Kaiser Family Foundation and other research organizations show that sexual content aimed at children has increased steadily since the 1990s. You just have to follow the money.

Times were prosperous, Britney Spears emerged as the sexy schoolgirl on MTV, and 'tweens had plenty of disposable income -- a perfect alignment for marketers trying to expand into a new demographic. By 2007, 8- to 12 year-olds' consumer spending was $170 billion worldwide, according to the market research firm Euromonitor.

The book, published this month by Overlook Press, is the culmination of 13 years of research by Durham, an associate professor in the University of Iowa School of Journalism and Mass Communication, part of the UI College of Liberal Arts and Sciences.

In the book, Durham identifies five myths of sexuality and provides advice and resources for caring adults who want to discuss the issue with young girls.

The myths are:

• If you've got it, flaunt it. Bare a "Barbie body" as often as you can. But don't celebrate or enjoy any other body type. "It's really excluding a lot of girls from enjoying and recognizing pleasure in their own bodies," Durham said.

• Anatomy of a sex goddess. "Media reinforce a ridiculous ideal of being both extremely thin and voluptuous -- a body not found in nature," Durham said. "You have to go through borderline starvation and plastic surgery to get it."

• Pretty babies. Representations of sexual girls are getting younger and younger. Many of the images presented as the most sexually desirable are images of girls as young as 11 or 12. "It's problematic in many ways: It encourages sexualization of girls too young to make good decisions about sex. It legitimizes the idea that young girls should be looked at as sexual partners. And, presenting pre-pubescent bodies as the sexual ideal pressures grown women to achieve the body of a child who hasn't even matured yet," Durham said.

• Sexual violence is hot. Media aimed at children -- like PG-13 "slasher" movies -- convey the message that violence is sexy or that sex should be violent.

• Girls don't choose boys; boys choose girls -- and only hot girls. Women and girls are supposed to focus on pleasing men. But little emphasis is placed on women taking pleasure in their own sexuality or bodies, or on guys striving to please gals, Durham said. "It's a very one-way construction of sex."

"The book definitely isn't anti-sex," Durham said. "It starts with the recognition that girls are sexual -- everybody's sexual -- but that girls deserve good information that will help them make good decisions.

"We have the highest rate of teen pregnancy in the industrialized world, and a study by the Centers for Disease Control just reported that 1 in 4 teen girls in the U.S. has an STD. Clearly we're not giving them the kind of information they need to take care of themselves sexually and transition to adulthood in safe ways."

Durham encourages parents, teachers and counselors to jump-start conversations about sexualization of young girls in the media. She says girls should be asked to look through a teen magazine and discuss the messages. How seriously do they take them?

"There's this hesitance to talk about these issues, especially before kids reach adolescence," Durham said. "But often, when parents finally do bring it up, it's too late. Kids have already had their sexual understanding shaped by media. We need to be having a lot of open discussions about the sexualization of childhood and what constitutes healthy sexuality. I don't think we should neglect our responsibility as adults and leave them to navigate this terrain on their own."