抄録
Food is generally recognized as the main source of human intake of polychlorinated dibenzo-p-dioxins, dibenzofurans, and dioxin-like polychlorinated biphenyls, which are known collectively as dioxins. A total diet study is a useful method of estimating the average dietary intake of contaminants. We have conducted a nationwide total diet study of dioxins for the general Japanese population ((≥ 1 year old) annually since 1998. Here, we report the total diet study results for 2017 and also discuss the time trend of dietary intake of dioxins from total diet study results obtained over the last 20 years. High-resolution gas chromatography coupled with high-resolution mass spectrometry has been used to provide sensitive and reliable determination of dioxin concentrations in a total diet sample. In 2017, the average daily intake of dioxins for a person weighing 50 kg, calculated at non-detected congener concentrations assumed to be equal to zero, was estimated to be 0.65 pg TEQ (toxic equivalents)/kg body weight (bw)/day. The value was well below the tolerable daily intake of 4 pg TEQ/kg bw/day for dioxins in Japan. The average intake was highest from fish and shellfish, followed by meat and eggs. The TEQ contribution of the fish and shellfish group to the total dietary TEQs was significant (88%). The latest average intake was about one-third of the average intake in 1998. Overall, the average dioxin intake appeared to be decreasing gradually during the period of study. This decreasing trend in the dietary intake of dioxins was mainly influenced by the decreased dioxin intakes from two food groups, fish and shellfish, and meat and eggs.
