A major wastewater treatment plant is due to begin operation on the outskirts of Tokyo on Monday after a government study said high levels of lead and other heavy metals were found in the wastewater from the plant.
The plant, part of a government-run wastewater management scheme, will be operated by Tokyo Electric Power Co. (TEPCO).
A company spokesman said the wastewater treatment unit would be used for cleaning up toxic metals found in municipal water.
Lead, copper and arsenic were found as high as 400 micrograms per cubic metre in samples collected at the plant, TEPCO said.
It said the contamination was found in water from the sewage treatment plant that has been used since 2008 to treat sewage from over 10,000 households and businesses.
A large section of the plant is expected to be filled with wastewater and the rest will be treated.
The ministry has been investigating the issue.
Lead is the main element found in lead-based paints, cosmetics, water filtration systems and fertilisers.
In a separate incident, TEPEC found traces of lead in drinking water at a wastewater treatment facility in Osaka, Japan’s third-largest city.
Lead in drinking-water samples from around 300 households in Osaka was found to have high levels.
Lead was found at levels as high for some of the people who took part in the study as well as in the drinking water from other municipal facilities, which were not involved in the case, according to a TEPCOC official.
Lead can cause serious health problems, including brain damage, developmental delays and low birth weights.
The government has been conducting a series of water quality surveys since 2011 to investigate the health effects of drinking water and wastewater from wastewater treatment plants, which use toxic chemicals and fertiliser to treat wastewater and produce drinking water.
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