The Shadow of Tokyo as Told by the Formation of Hexavalent Chromium: Memories of the City of Oshima, Koto-ku (1970s-1990s)

The Shadow of Tokyo as Told by the Formation of Hexavalent Chromium: Memories of the City of Oshima, Koto-ku (1970s-1990s)
The events surrounding hexavalent chromium pollution in Koto and Edogawa wards are not simply a case of pollution, but a story that quietly illuminates the other side of Tokyo's urban development from the postwar period to its period of rapid economic growth. In particular, the chemical sludge lying underground in Oshima, Koto-ku, symbolizes the structural problems that the city of Tokyo had pretended not to see in order to grow. During the high-growth period, plating and chemical plants were concentrated along rivers and in reclaimed land, and the waste liquid and sludge containing hexavalent chromium were buried underground without being treated. This was a time when shadows were quietly accumulating behind the lights of the city.
Around 1970, as awareness of environmental issues rose nationwide in the wake of the Diet session on pollution, yellowish soil and corroded drums were found in the Oshima area, and the severity of hexavalent chromium contamination became visible. In areas that had already been converted to residential areas, residents' concerns spread rapidly and the government's accountability came under scrutiny, and lawsuits were filed against the Tokyo Metropolitan Government in the 1980s and 1990s, with the main issues being the extent to which the government was aware of the danger and whether it had taken appropriate measures. While the Tokyo District Court found no evidence of willfulness or gross negligence, the case was significant in that it recognized the inadequacy of the administrative response and clearly pointed out that the contamination problem had been neglected for a long time.
Although the Tokyo Metropolitan Government has promoted decontamination work and groundwater monitoring since the 1990s, it is extremely difficult to completely remove hexavalent chromium because it retains its toxicity for more than 100 years if it remains in the deeper layers. The land in Oshima, Koto-ku, still bears the history of distortion of urban formation and environmental burden. The problem of hexavalent chromium contamination is not limited to the local area, but leads to the larger question of what has been sacrificed by Japanese cities in their prioritization of economic growth.