The Canadian total diet study design: 1992–1999

Abstract

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.

Keywords:

• dietary intake
• dioxins
• PCBs
• pesticides
• total diet study
• trace elements

Acknowledgements

The authors thank Don Forsyth, Chief, Food Research Division; Barbara Lee, Director, Bureau of Chemical Safety; Samuel Godefroy, Director General of the Food Directorate; and Henry B.S. Conacher (former Chief, Food Research Division, retired) for their personal interest, promotion and organisational support for the TDS. Also, appreciation is expressed for the initiative and efforts of Rudolf Krska, University of Natural Resources and Life Sciences, Tulln, Vienna, Austria, in facilitating the combination and publication of these TDS findings during his sabbatical stay in Canada in 2009–2010.

The purchase of food samples and the preparation of food composites were organised by Russ Graham (retired) between 1985 and 1996 and by Frank Lancaster (retired) in 1998–1999. The food samples were collected by the Field Operations Directorate of Health Canada in 1992–1996 samplings and by the Department of Indian Affairs and Northern Development in 1998 from Whitehorse. The Canadian Food Inspection Agency (Department of Agriculture and Agri-Food) took over this function in 1999 and subsequent years. Thanks are due to Elizabeth K. Forbes, Co-ordinator, Food, Nutrition and Risk Management Programs, Kemptville Campus, University of Guelph, Kemptville, Ontario, for her invaluable advice on the preparation of the food composites and for organising and supervising the composite preparation.

The nutritional components of the TDS were promoted and supported by Kevin Cockell, currently Chief, Nutrition Research Division, Health Canada, while updates to food consumption were provided by both the Bureau of Nutritional Sciences and the Bureau of Biostatistics and Computer Applications.