This cross-sectional survey was conducted from December 2005 to February 2006 in the geographic area of Naples (Italy). A two-stage cluster sampling technique was employed to draw the required sample. In the area surveyed there were 40 schools and each school was considered a cluster. The first stage consisted of selecting four clusters through random sampling. The second stage consisted of randomly select 255 adults from the parents' files of each sampled school that contained 500 students.