Abstract
Food is generally recognized as the main source of human intake of persistent organic pollutants, such as dioxins and polychlorinated biphenyls (PCBs). A total diet study (TDS) based on a market basket approach is a useful method of estimating the average dietary intake of contaminants in populations. We have conducted annual nationwide TDSs in the general Japanese population (≥1 year old) for dioxins since 1998 and for PCBs since 1977. The national average intake of dioxins was estimated to be 0.44 pg TEQ (toxic equivalents)/kg body weight (bw)/day in 2021. The value was about 11% of the Japanese tolerable daily intake (TDI) of 4 pg TEQ/kg bw/day for dioxins in Japan. The TEQ contribution of the fish and shellfish group to the total dietary TEQs was significant. The latest average dioxin intake was about one-fourth of the average intake in 1998. The national average intake of PCBs was estimated to be 6.7 ng/kg bw/day in 2021. The value was about 0.1% of the Japanese provisional acceptable daily intake (PADI) of 5 μg/kg bw/day. The contribution of the fish and shellfish group to the dietary PCB intakes was significant. The latest average PCB intake was about one-tenth of that in 1977-1978. We also conducted a Monte Carlo simulation to obtain information on the distribution of dioxin intakes from fish and shellfish in six age-groups of the Japanese population. The estimated average and 95th percentile values of the intake distributions of the age-groups were 0.89-1.9 pg TEQ/kg bw/day and 3.3-7.1 TEQ/kg bw/day, respectively. The estimate 95th percentile values of four of six age-groups exceeded the TDI. The estimated average and 95th percentile values of early childhood (1-3 years) was the highest among the six age-groups. Fish groups, including horse mackerel, sardine, yellowtail, and fishery products (salted and dried fish etc.), are the main sources of dioxin intake from fish and shellfish in all 6 age-groups. Thus, dietary intakes of dioxins and PCBs in Japan has been decreasing, and the current intakes as estimated by TDSs were well below the Japanese TDI and PADI. However, overconsumption of fish and shellfish would lead to an increase in our intake of dioxins and PCBs from food, and a balanced diet is recommended.
