This time it's a finding that one out of every seven Los Angeles high schoolers with a mobile has sent a sexually-explicit text message or photo.

Survey results in Pediatrics also show that teens who sent racy texts are seven times more likely to be sexually active than those who never sexted.

Says study leader Eric Rice of the University of Southern California in Los Angeles: "What we really wanted to know is: Is there a link between sexting and taking risks with your body? And the answer is a pretty resounding 'yes.'"

It follows a study of Houston high schoolers. There, one in four teens have sent a naked photo of themselves through the internet, and those kids are also much more likely to be having risky sex.

Girls in particular who'd sent naked photos were more likely to engage in risky sex, had multiple partners and used alcohol and drugs before sex.