May 19, 2012 | Jiji Press | Shared as an educational material
The discovery of formaldehyde exceeding the government-set limit in water has caused suspensions of some water-purifying facilities in the Kanto eastern Japan region by Saturday, disrupting water supplies to 344,000 households in five cities of Chiba Prefecture.
In Chiba, east of Tokyo, water intake was suspended at the Kamihanawa water treatment plant in the city of Noda, the Kitachiba plant in Nagareyama and the Kuriyama plant in Matsudo after formaldehyde above the limit of 0.08 milligram per liter of water was found there.
In Noda, water supplies were suspended from Saturday morning at about 41,000 households, or two-thirds of the total in the city. In the city of Kashiwa, water outage affected about 161,300 households, or almost all of the total there, from noon.
To cope with the situation, the two cities distributed stockpiled water to residents at such locations as playgrounds of elementary and junior high schools.
Supplies were halted at about 68,800 households in Nagareyama, 38,000 in Yachiyo and 35,000 in Abiko.
Water intake remains suspended at the Kamihanawa facility, but restarted at the Kitachiba and Kuriyama facilities on Saturday afternoon as the formaldehyde contamination levels dropped. Water supplies to affected households in the five Chiba cities are thus expected to resume gradually toward Sunday morning, officials said.
Water intake was also temporarily suspended at the Gyoda water-purifying facility in Gyoda, Saitama Prefecture, and at the Tobuchiiki Suido water facility in the town of Chiyoda, Gunma Prefecture. The suspensions were lifted in line with a drop in the formaldehyde levels.
Formaldehyde, a chemical substance used as a material for plastic and adhesives, is thought to be a cause of sick building syndrome. Inhaling formaldehyde could increase the risk of cancer while the health impact from drinking water or beverages containing the chemical substance has not been confirmed, according to officials of the Saitama prefectural government.
The prefectural governments of Gunma and Saitama have been investigating the contamination by focusing on the possibility that a substance that is transformed into formaldehyde when mixed with chlorine may have flowed into rivers, according to prefectural government officials.
Because relatively high levels of formaldehyde have been found in the Karasu River near the city of Takasaki, Gunma Prefecture, the contamination problem may be traced to the river, which is a tributary of the Tone River running through the Kanto region, according to the officials.
As part of the investigation, the Gunma government on Saturday sampled water from seven locations of the Karasu River and three of its tributaries, and started to examine wastewater from factories located along the rivers.
According to preliminary test results, formaldehyde levels were not high for water samples collected at three of the seven sites, officials of the prefectural government said. Detailed results for all sampled water and wastewater from one factory will be available as early as Sunday morning, the officials said.
In the test, chloride will be mixed with the sampled water to see if formaldehyde will be produced, they said, noting that a chemical substance may have been transformed into formaldehyde at the water treatment plants in question during the process of disinfecting water using chloride.
Investigations have also been carried out at multiple rivers in Saitama Prefecture that flow into the Tone River.