The water system in Chiba and Saitama are contaminated, said Saitama Prefecture and Chiba Prefecture on Friday, May 18.
Chiba and Saitama are neighboring to Tokyo.
According to NHK news, the affected population may be up to 2.9 million people in Chiba and Saitama.
They found the high amount of formaldehyde at various water purification plants.
Two plants in Gyoda, Sattama and Noda, Chiba already stopped taking the water from Tone River System.
Local governments started arranging the water trucks just in case.
Gyoda Water Purification Plant detected maximum 0.168 milligram per liter of formaldehyde in the water from the various tests between May 17 and May 18. The government regulation was set to 0.08 milligram per liter. The result was twice as much as the legal limit.
According NHK 9 O'clock news, the current amount does not give serious effects to human body. However, they will continue to monitor the contamination level.
The following is the list of contamination levels between May 17 and May 18, 2012.
The cause of the contamination is still unknown. The local agencies is continuing the investigation.
If you are living in the affected area, please pay attention to the annnouncement by the local government.
Formaldehyde is poisness chemical compound mainly used for resin and preservatives.
If you intake a little amount of it, it could cause sore throat and headache. If people take a lot of it, people may have difficulty breathing, risk of getting cancer, and resuled in death in the worst case senario.
According to Japanese government standard, the legal limit of formaldehyde in the water system is 0.08 milligram per liter