Dietary exposure to perchlorate of the Hong Kong population through a total diet study

Perchlorate and its salts occur naturally in the environment and are also environmental contaminants arising from human activities. Perchlorate has been reported to occur in a wide range of foods including vegetables, fruit, milk and dairy products. Dietary exposure assessment of the Hong Kong adult and younger populations to perchlorate was included in the second Hong Kong Total Diet Study (TDS). A total of 187 commonly consumed food items were collected and prepared 'as consumed'. A total of 374 composite food samples were analysed for perchlorate by isotopic labelled LC-MS/MS. Dietary exposure to perchlorate was estimated based on the analytical results and the food consumption data of the local population. The results showed that 249 out of 374 composite TDS samples (from 144 out of 187 TDS food items) tested positive for perchlorate, with a detection rate of over 75% (at TDS food item level). By comparing perchlorate levels across TDS food items, pumpkin was identified having the highest mean concentration (upper bound: 310 µg/kg), followed by Chinese amaranth (120 µg/kg) and Chinese parsley (67 µg/kg). Perchlorate was mainly contributed from the food group of 'Vegetables and their products', followed by 'Beverage, non-alcoholic' and 'Cereals and their products'. Both the highest upper bound exposure to perchlorate for high consumers of adult and younger populations contributed to 2.7 and 3.8% of its provisional maximum tolerable daily intake (PMTDI) value. Hence, the findings of this study indicated dietary exposure estimates of perchlorate for the average and high consumers of Hong Kong adult and younger populations were unlikely to pose a health risk.