1. A. Jeanne M. van Loon, University of Limburg, Department of Epidemiology, Maastricht, the Netherlands, Address correspondence to: A. J. M. van Loon University of Limburg Department of Epidemiology, P.O.B. 616 6200 MD Maastricht The Netherlands
2. Johannes Burg, University of Limburg, Department of Health Education, Maastricht, the Netherlands
3. R. Alexandra Goldbohm, University of Limburg, Department of Epidemiology, Maastricht, the Netherlands, TNO-Toxicology and Nutrition Institute, Department of Nutrition, Zeist, the Netherlands
4. Piet A. van den Brandt, University of Limburg, Department of Epidemiology, Maastricht, the Netherlands