An Environment Ministry advisory committee recommended Monday that an environmental standard for dioxin in the sediment of rivers and other bodies of water be set at 150 picograms per gram.
The recommendation was submitted to Environment Minister Hiroshi Ohki, and a relevant ministerial ordinance will be issued in August, making the standard legally binding.
The standard will join limits on dioxin in water, air and soil as well as emission limits for waste incinerators — the major source of dioxins — and other emitters of the carcinogen.
According to ministry officials, the new standard is based on the amount of dioxin in sediment corresponding to the allowable amount in water, which is 1 picogram per liter. A picogram is one trillionth of a gram.
The panel said that measures such as dredging and covering sediment with concrete or sand be adopted at sites above the 150 picogram level.
In a 2000 survey, 14 of 1,836 sites around the nation topped the new level. Overall sediment was found to average 9.6 picograms, with a high of 1,400 and a low of 0.0011 picograms. The government will monitor sediment for dioxin contamination annually.
No other nations have established legally binding environmental dioxin standards for sediment, according to the ministry.