RESUMEN
A study was carried out with a group of pre-school children staying at the central nursery of the University of São Paulo and with a group of elderly living in private institutions in São Paulo, Brazil, with the aim of evaluating the contents of toxic elements present in the diets of these groups. For sampling, the duplicate portion technique was used, which consisted of collecting all the foods and beverages consumed during three consecutive days. A radiochemical separation procedure was developed and applied to the determination of As, Cd, Sb, W, Th and U, by means of retention of these elements in the resin Chelex 100 and inorganic exchanger tin dioxide in an appropriate medium. The elements analysed presented levels of ingestion below the maximum levels recommended by the World Health Organization (WHO), and thus can be considered as not presenting any health hazard to the individuals studied in the present work.