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As ardent Hanshin fans count down to the roaring Tigers’ much-awaited baseball title, environmentalists wary of the revelers’ ultimate expression of rapture — a dive into Osaka’s Dotombori River — warn that the waterway is full of toxic sludge.

The poisons that await them include particles of heavy metals such as lead and zinc, dioxins and E-coli bacteria.

Hiroaki Ishiga, a Shimane University professor who studied the heavy metal content of the sludge, says samples taken from Dotombori showed around 10 times the concentration of heavy metals compared with muddy waterways elsewhere.

“Heavy metals are basically poisons. It’s crazy to dive into a place like this,” Ishiga said.

Dotombori River — actually a man-made canal built in the early Edo era that runs through Osaka’s busy Minami area — is traditionally “the place to be” when the people of Osaka celebrate victories in major sporting events, including the 2002 World Cup soccer tournament and the most recent Hanshin Tigers victory 18 years ago.

To determine the exact concentration of heavy metals in the Dotombori sludge, Ishiga took samples from five locations between Ebisu Bridge and Hiyoshi Bridge in March.

He found between 140 and 210 parts per million of lead, 650-700 ppm of zinc, and 470-620 ppm of copper.

Ishiga says the Dotombori sludge contains heavy concentrations of residues from waste water discharged by nearby industrial plants as well as exhaust fumes discharged by cars, all of which has been absorbed into organic matter.

Under normal circumstances, Ishiga says, these organic substances are dissolved by microorganisms or through oxidization, a process that separates heavy metals from other elements. This purification process, however, works poorly in the Dotombori where the flow of fresh, oxygen-rich water is restricted through sluices.

In a separate study conducted by the Osaka City Institute of Public Health and Environmental Sciences in October last year, researchers found that the sludge contains dioxins twice the level the government considers safe for the environment.

In anticipation of river-jumping revelers, the Osaka city office of river administration cleaned up the waterway in July, removing huge amounts of garbage, including discarded bicycles. The sludge, which the office says is 1 meter deep in some places, remains untouched.

Heavy metals and dioxins, however, are only some of the health hazards faced by Hanshin fans.

Another survey conducted by Osaka health authorities in August shows that the concentration of E-coli bacteria in the waterway is more than five times the level that is acceptable in water used by swimmers.

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