Samples taken from the Hikichi River in Fujisawa, Kanagawa Prefecture, late last year showed dioxin levels up to 16 times the recently-set environmental standard, the Environment Agency announced on Monday.
The samples, part of the agency's 1999 national dioxin survey, found values ranging from 1.1 to 16 picograms per liter of water. The national environmental standard which went into effect in January is 1 picogram per liter. A picogram is a trillionth of a gram.
The announcement follows one last Friday that record levels of dioxin had been found in water released from the Ebara factory -- as high as 8,100 picograms per liter of water.
The water was sampled at Fujimi Bridge, about 2,500 meters downstream from where a stream polluted with dioxin feeds into the river. The dioxin is believed to have come from unprocessed water used in a waste incinerator operated by Ebara Corp. that was accidentally flushed directly into the stream.
Agency officials urged citizens to remain calm and said that water from the river is not in an area used by fishermen, is not used for human consumption or irrigation and they "are not especially worried about the (effect on) the lives of local residents."
The results of a 1998 national study on dioxin in fish found carp in the river to have an average of 12 picograms per gram and crucian carp to have some 9.2 picograms per gram, nearly six times the national average of 2.1 picograms.
But agency officials also said dioxin levels in young sardines off the coast of Kamakura, where the river feeds into the ocean, showed a "sufficiently low" level of 0.4 picograms per gram. The agency has set up a policy network to continue tests to determine the extent of the dioxin pollution and its potential impacts.