This study aims to determine the dietary exposure to heavy metals of secondary school students in Hong Kong so as to assess whether there are any risks to their health. The potential for any risks to health are assessed by comparing the dietary exposure to heavy metals with the appropriate safe exposure levels - Provisional Tolerable Weekly Intakes (PTWIs) recommended by the Joint FAO/WHO Expert Committee on Food Additives (JECFA). PTWI is an estimate of the amount of a contaminant that can be ingested over a lifetime without appreciable risk.