RESUMEN
The use of alcohol, tobacco, marihuana, cocaine, and bazuco was examined in a cross-sectional study or a random sample of 512 secondary-school students enrolled in public and private schools in Cali, Colombia. The overall prevalence of use for any of these substances was 59.38 percent in the public schools and 36.96 percent in the private schools (z = 4.6, P 0.05). The probability of finding an alcohol user was about 55.26 percent. The frequency of use for all the substances was 18.9 percent in the public schools and 7.46 percent in the private ones. Experience with marihuana, cocaine and bazuco was more frequent in the public schools. The average ages of users (19.91 years) was higher than that of non-users, (16.25 years): t = 8.34, P 0.05. Students in the public schools with a family history of mental illness had almost a ninefold greater risk of being substance users (RR = 8.84, IC 95 percent = 1.22-3.37); among students in the private schools, having personal conflicts with authority figures (teachers and the police) was a significant risk factor (RR = 2.03, IC 95 percent = 1.22-3.37)