Advancement in methodology for the estimation of dietary exposure to chemical substances of the second Hong Kong total diet study

The first Hong Kong Total Diet Study (1^st HKTDS) was conducted in 2010-14 with the aim of obtaining realistic exposure data to contaminants and nutrients for the adult population in Hong Kong. A core food model was applied to reflect the eating habits of the local adult population and to cover the most important foods in terms of consumption and selected substances contribution. The second (2^nd) HKTDS is being conducted since 2023 with the use of the latest food consumption data obtained for the Hong Kong population. By applying the same core food model as that employed in the 1^st HKTDS and other new measures, the TDS food list for the 2^nd HKTDS has been updated to include more food items (187 in total) against the previous list (150). Apart from reflecting the changes in consumption of foods, the TDS food list included more food items considered particularly important for dietary exposure estimation such as food items reported to have high levels of certain chemical substances. The opportunity has been taken to update other aspects of the methodology of the 2^nd HKTDS to align with the current international practices and recommendations, including changes in food sampling, sample preparation, food mapping and analytical methods achieving lower LODs, and the underlying reasons. The updated methodology could better reflect the real exposure to chemical substances than the previous study.