OSAKA – Dioxin found buried on Maishima Island is approaching dangerous levels and thus more environmental testing must be carried out, a scientist with Greenpeace Australia warned.
Darryl Luscombe, a toxin expert who assisted Sydney Olympic organizers in formulating a cleanup response to a similar problem, said once construction for an Olympic stadium on Maishima begins, dioxin in the soil may pose a health hazard to those working at the site.
In mid-February, the city of Osaka released an environmental report that documented dioxin levels in the soil on Maishima, Yumeshima and the surrounding bay. The report was based on tests conducted last fall at 15 different locations.
Dioxin levels of between 1.2 and 2.1 picograms per gram were found in soil samples taken at five locations on the northern end of Maishima Island. A picogram is one-trillionth of a gram.
Samples were taken at roughly 50 cm increments to a depth of 7 meters. Their dioxin readings were well within Japan’s environmental guidelines, and Luscombe said they were very low.
However, at between 17 and 22 meters, it was a different story. Because the original landfill used to form the northern end of the island consisted of incinerated waste and raw sewage, dioxin levels of between 230 and 940 picograms per gram were discovered.
“At those levels, you’re very close to what would be considered hazardous to human health, especially to the health of construction workers who would be digging on the site,” Luscombe said.
Luscombe worked with Greenpeace Australia and the Sydney Olympic Committee to formulate a cleanup of Homebush Bay, part of the Olympic Village.
The bay had once been an industrial zone, and, in 1996, the area and surrounding waterways were found to have levels of PCB and other dioxin nearly 14,000 times the legal limit.
Part of the area was cleaned up by Greenpeace in 1997, and Sydney Olympic officials have announced plans, with Greenpeace’s endorsement, to clean up most of the remaining waste.
Australia’s current environmental regulations call for dioxin levels of 1 nanogram per gram, or the same ratio as 1,000 picograms per gram.
Osaka officials note that, compared with Germany and Holland, where the dioxin standard is 1,000 picogram for residential areas, even the highest levels of dioxin found on Maishima would be considered under the limit in those countries.
City officials claim their dioxin tests were by the book. However, Luscombe said, and city Olympic officials admitted, that the numbers could be higher because of the way the testing was carried out.
Samples taken at every 50 cm of one boring were not individually analyzed but, rather, mixed after being brought to the surface with other samples, and a composite analysis was taken.
“This is the same way that Australia does its testing. The only way to determine what the highest levels of dioxin are is to analyze pure samples, which means more testing and monitoring,” Luscombe said.
Osaka environmental officials said they will continue to monitor the bay area surrounding Maishima Island. They have announced no plans to conduct additional dioxin tests in the areas where incinerated waste is buried.