A Gunma-based industrial waste disposal firm is suspected of dumping the toxic liquid that polluted part of the Kanto region’s water system last week, the Saitama Prefectural Government said Friday.
When its officials conducted an on-site inspection last week at Dowa Hightech Co. in Hojo, Saitama Prefecture, they found it had hired a contractor from the city of Takasaki in Gunma Prefecture to process industrial waste. The company’s name is being withheld by the prefectural government.
The contractor is suspected of discharging toxic fluids from the waste it processed into the Karasu River, including hexamethylenetetramine, created from ammonia and cancer-causing formaldehyde. The river runs through Gunma and merges with the Tone River — the main water source in Kanto — where formaldehyde levels spiked alarmingly last week in some areas.
Dowa Hightech, a producer of chemical products, has asked the contractor to clean up the affected areas and dispose of the toxic liquid, including the total nitrogen levels it might have contained, Takehiro Narita of the firm’s planning division told The Japan Times on Friday.
The contractor is suspected of incorrectly processing the waste before it was discharged into the river, Narita said.
“If they had processed the total nitrogen content appropriately, it’s impossible that such high levels of hexamethylenetetramine would have been released,” he said.
Dowa Hightech did not inform the disposal company that the waste might have contained hexamethylenetetramine, claiming it was not required to do so by law and that waste-disposal firms are supposed to factor in the possibility anyway.
But a legal battle may be brewing as Takashi Tajima, an official at the Saitama Prefectural Government’s environmental bureau, argued that the industrial waste disposal law requires clients of such contractors to list any chemicals that might produce formaldehyde during the disposal process in the contract.
Tajima said prefectural authorities will continue to investigate the matter to determine whether Dowa Hightech and the contractor violated any laws.
Chiba Prefecture was forced to temporarily turn off the water supply to cities including Noda, Kashiwa and Nagareyana after formaldehyde levels in the Tone River system spiked above the government-set threshold of 0.08 milligrams per liter, affecting more than 340,000 households.
On Thursday, the health ministry and the Environment Ministry announced they had identified hexamethylenetetramine as the source of the formaldehyde in the Tone River system, based on water samples taken at a water purification facility in the city of Nagareyama, Chiba Prefecture.
The ministries said that up to 6 tons of hexamethylenetetramine might have been poured into the Tone River but that they do not anticipate a major environmental impact, as the levels were in the range of 0.04 to 0.2 mg per kilogram.
Hexamethylenetetramine is used for medical purposes such as the treatment of urinary tract infections, and has also been approved as a food additive by the European Union.
At present, Japanese law on water pollution and industrial waste disposal does not designate hexamethylenetetramine as a toxic substance and its usage is not regulated.