Dioxins, Endocrine Disrupters Not Decreasing in Japan's Rivers

No clear downward trend has been seen in the concentrations of dioxins and endocrine disrupters in Japan's major (class I) rivers, according to the report of a fiscal 2004 survey on the topic, issued by the Ministry of Land, Infrastructure and Transport on August 2, 2005.

Dioxin concentrations in river water were measured at 241 sites, and 11 were found to exceed the minimum level at which regular monitoring becomes mandatory (i.e., at half the value of the environmental quality standard). Meanwhile, data from two other sites were noted only for reference, as the data were thought to be greatly affected by suspended matter due to rainfall during the survey, but it was noted that at one site, the dioxin concentrations exceeded the environmental standards, and at the other they exceeded the level requiring regular monitoring. Dioxin concentrations in bottom sediment were below the level requiring regular monitoring at all of 242 sites surveyed.

Contamination by endocrine disrupters was tested in river water at 94 sites. At 28 sites river water was found contaminated by at least one of the chemicals targeted by the survey. At 12 of the 28 sites, the concentrations of these chemical exceeded the levels tentatively set as environment standards for this survey, with this level of contamination observed for the first time at seven of the 12 sites. On the other hand, concentrations dropped below the tentative standards at 17 of 22 sites where the standards had been exceeded in the fiscal 2003 survey. Bottom sediment contamination by one of the targeted endocrine disrupting chemicals was tested at 22 sites, and one of these chemicals was found at eight of these sites.

Based on these results, the ministry concluded that there is no clear correlation between sites with high concentrations of dioxins and those with high concentrations of endocrine disrupters, and that no clear downward trend is evident year-to-year in the levels of either dioxins or endocrine disrupters. The ministry plans to continue the survey to accumulate data for its future countermeasures.



Posted: 2005/12/02 03:31:21 PM
Japanese version