The Canadian total diet study design: 1992–1999

This paper describes the design of the fourth phase of the Canadian total diet study, conducted for the period 1992–1999. During this phase, complete sets of foods were purchased from eight cities (from one of them twice). For each of the sets, individual foods were prepared as for consumption into about 140 different food composites at Kemptville College, homogenised and bottled. Water from Kemptville, Ontario, was used for the preparation of the foods. The composites were stored frozen at −20°C and then analysed in the Food Research Division for chlorinated dioxins and dibenzofurans, pesticides, PCBs and trace elements. The analytical results were combined with average food consumption values for different age/sex groups, and dietary intakes were calculated. The design of the total diet study provided information to achieve the following goals: (a) background concentrations of the chemicals in the 140 different food composites, (b) average dietary intakes of the chemicals by the population and by different age/sex groups, (c) percent contribution of individual foods and food groups to the dietary intakes, (d) identification of individual contaminated foods and (e) identification of trends in human exposure with time.