It has been on the street for the last few years: displays of cleavage and pelvis on teen girls and bling and strut among boys. These are brought to us, experts say, by raunchy music videos and the "soft porn" look of some mainstream advertising as well as sexual content on TV in general.

The messages flowing from these products of our increasingly sexualized culture are not only responsible for the streetwalker and gangsta looks. It turns out they also have a direct influence on the earlier onset of sexual behaviour and may be responsible for the offhand manner in which some young people engage in sex.

That's because, first of all, for two-thirds of young people, the media is where they learn about sex, according to a 2003 paper by the Canadian Pediatric Society. What they learn worries those who work with teens in crisis situations.

"We know," says McGill University child psychologist Rina Guptha, "that kids are incredibly influenced with respect to fashion and the messages of these music videos."

What they get there has more influence than was previously understood. A study published last year by the American Academy of Pediatrics in the journal Pediatrics suggested that about two-thirds of all TV programs contain sexual content and might actually contribute to "precocious adolescent sex."

"Watching sex on TV predicts and may hasten adolescent sexual initiation," the AAP study concluded, contributing to the rise of what's been termed "age compression."

When examining the sexual activity and TV viewing habits of 1,792 adolescents age 12 to 17, researchers found that the young people who watch the most sexual content acted older than their years. For example, "a 12-year-old girl at the highest levels of exposure (to sexual content on TV) behaved like a 14- or 15-year-old at the lowest levels (of TV viewing)."

Lead researcher Rebecca Collins told Reuters news service: "This is the strongest evidence yet that the sexual content of television programs encourages adolescents to initiate sexual intercourse and other sexual activities."

The study, conducted by the RAND Corporation, found that teens who watch a lot of television with sexual content "are more likely to initiate intercourse in the following year."

The effect of this sexual content is strong. The study showed that youths in the highest percentile of TV viewing could be predicted to have twice the "intercourse initiation" of those in the lowest percentile. Thus, the more an adolescent viewed sexual content on TV, the greater the incidence of sexual behaviour.

While studies show teen pregnancy rates and reports of sexual intercourse among younger teens are declining in the U.S. and Canada, more girls under age 15 are engaging in sexual activities like oral sex.

From the U.S. National Centre for Health Statistics, the newly released results of an exhaustive benchmark survey of U.S. teens conducted in 2002 show 42 per cent of girls and 44 per cent of boys between 15 and 17 had engaged in oral sex, either giving or receiving. In addition, a surprising number of girls between 15 and 19 - 10.6 per cent - said they had had same-sex sexual contact, compared with 4.5 per cent of boys.

And despite birth control and falling birth rates, there has been an alarming increase in sexually transmitted diseases among teens. STDs have increased dramatically, according to a study reported in the Canadian Journal of Human Sexuality, which found the highest chlamydia infection rates in Canada among 15- to 19-year-old females; the chlamydia rate in this age group increased to 1,200.4 per 100,000 in 2000 from 971.6 per 100,000 in 1996.

Guptha, who works with teens at risk, believes the influences they're getting through the media "are much more intense and more complex and confusing - primarily in the music videos." In the last four or five years, she says, the increase in sexual content on screen has been staggering, all the way from faux lesbianism to porn-type scenarios.

Her concern focuses on how out of synch the behaviour is with teens' ability to handle the consequences. "Developmentally, they're incorporating these images, assimilating them, but they don't have enough emotional maturity," Bazergui says.

Adolescence, she says, takes time. "It's a rite of passage, about figuring out who you are, about building connections and relationships. I think adolescents are skipping over that period. Now they're thrown into the whole sexual arena, not really having the emotional tools to deal with it."

Seeing young people who are sexually active, needing the morning-after pill and having sexual relationships with different people has made it clear to Bazergui that "they're not really understanding what they're getting themselves into.

In Hudson, an irate letter to the editor of the local paper during the summer on the subject of teen sexualization pointed out the preteen favourite Avril Lavigne on the cover of Cosmopolitan alongside the headline "10 Great Sex Tricks to Try on Your Boyfriend."

It's rare, Bazergui says, that teens can have a critical perspective on this flood of sexual imagery. "It's what they know," she says, "it's familiar to them. But you sort of wonder what it does to their sense of self."

There are some positive aspects to all of this, Guptha believes. One is that parents are much more realistic than they used to be, a lot of them making sure their daughters have birth control and their sons use condoms.

But knowing about condoms and birth control doesn't give teens understanding about STDs and how they can be transmitted, she says. Nor does it help them navigate the pathway to sexual relations, which increasingly takes place in a nonchalant manner.

A survey used by U.S. author Sabrina Weill for her new book, The Real Truth About Teens & Sex is particularly telling. When asked whether sex should be romantic, nearly one-fifth of 1,059 12- to 17-year-olds surveyed answered: "Don't know."

"I think we've regressed," Bazergui says, "to a place where all young girls are seeing is sexual images, and boys are seeing females in these sexual ways.

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