Dietary Exposure to Dioxins, Polychlorinated Biphenyls, and Heavy Metals in the Tokyo Metropolitan Area from 1999 to 2014

Continuous surveillance of the dietary intake of dioxins, polychlorinated biphenyls (PCBs) and heavy metals in foods retailed in the metropolitan Tokyo area was performed from 1999 to 2014 using the total diet-market basket method based on food classification (14 groups) and data about food consumption in the Tokyo region, which were obtained from the National Health and Nutrition Survey in Japan. The daily intake of dioxins per kg of body weight for an average 50-kg adult body was 1.92 pg toxicity equivalency quantity (TEQ)/kg/day in 1999 and it decreased to 0.51 pg TEQ/kg/day in 2014. It is now estimated as being below 1 pg TEQ/kg/day in Tokyo. The daily intake of dioxins in fish and shellfish (group 10) accounted for more than 50% of total WHO-TEQs. In addition, more than 90% of the daily intake of dioxins came from fish and shellfish (group 10), meat and eggs (group 11), and milk and dairy products (group 12). The daily intake of PCBs was estimated as 0.038 -0.051 mu g/kg/day, which is 0.76%-1.02% of the Japanese provisional acceptable daily intake (ADD. The fish and shellfish group made the highest contribution to the total dietary intake of PCBs. During the period of this study, the dietary intake of PCBs remained at the same level, or decreased slightly. The daily intake of methylmercury and mercury remained at a low value and was less than the tolerable weekly intake (TWI) established in Japan. The major sources of methylmercury and mercury intake were fish and shellfish (group 10). The daily intake of cadmium also remained at a low value and it was less than the TWI in Japan. The major sources of cadmium intake were rice and rice products (group 1). There was no specific source of lead intake.