Prevention strategies based on scientific evidence working with families, schools, and communities can ensure that children and youth, especially the most marginalized and poor, grow and stay healthy and safe into adulthood and old age. For every dollar spent on prevention, at least ten can be saved in future health, social and crime costs.
UNODC Vienna, 2013, 2015
More data in:
http://www.unodc.org/unodc/en/prevention/prevention-standards.html