The level of dioxin in produce grown in Tokorozawa, Saitama Prefecture, is not substantially above the national average and does not pose any threat to human health, according to a set of emergency government studies released Thursday.
The Environment Agency, Ministry of Agriculture, Forestry and Fisheries and the Health and Welfare Ministry conducted joint research on dioxin concentrations in spinach and tea, as well as in the air, water and soil, in response to the panic stemming from a Feb. 1 TV Asahi report alleging that agricultural products grown near Tokorozawa, an area with a high number of waste incinerators.
According to the government results, the levels found “will not impact the health of people.” The three government organs, as well as Saitama Prefecture, officially declared later in the day that Saitama produced tea and spinach safe for consumption.
Researchers found that 10 bunches of spinach packed for shipping yielded dioxin concentrations of .0085 to .15 picograms per gram. A picogram is a one-trillionth of a gram.
The results are almost identical to those in a 1997 nationwide survey by the Health and Welfare Ministry, which found .025 to .37 picograms.
According to the ministry, an average diet including spinach with levels found in and around Tokorozawa would result in consumption of between 2.3 and 2.4 picograms of dioxin a day, less than the 10 picogram limit set by the ministry.
However, the Health Ministry is currently working with the Environment Agency to review the standard and will likely lower the limit to between 1 and 4 picograms, similar to those adopted by the World Health Organization, later this year.
Surveys of tea, for which Tokorozawa is famous, found an average of .81 picograms per gram, much lower than the 3.8 picograms per gram found in a study by the Tokyo-based Environmental Research Institute that were reported by TV Asahi.
Tea leaves steeped for one minute in water heated to 90 degrees produced no detectable dioxin. Tea leaves left for five minutes in 100-degree water produced a dioxin concentration of .002 picograms per liter.