Development of the Adolescent Exploratory and Risk Behavior Rating Scale ..Nicole Renee Skaar http://conservancy.umn.edu/bitstream/53807/1/Skaar_umn_0130E_10490.pdf
If you're interested in substance use, you can check this article :
Krank M, Stewart SH, O'Connor R, Woicik PB, Wall AM, Conrod PJ. Structural, concurrent, and predictive validity of the Substance Use Risk Profile Scale in early adolescence. Addict Behav. 2011 Jan-Feb;36(1-2):37-46. Epub 2010 Aug 10.
We have a translation in French (I'm not sure it's validated, but it has been used in a national adolescent population survey).
Intriguing question-depends of what you mean by high risk? But, the following compendium has a long list of delinquency and violence-related measures for youth: http://www.cdc.gov/ncipc/pub-res/measure.htm It won't specify if validated in French, but is a start. All best, M
I'd look at Jeffery Derevensky's work from McGill University in Montreal, Canada. He does a lot with risk taking (particularly gambling) and lives in a French-speaking part of Canada, so he might have something.