Traces of di-hydrogen oxide have been found in Shanghai's Huangpu River, local environment officials have admitted, weeks after rumours about the pollution shock first started spreading on the internet.
Although the river is well-known for the cocktail of chemical compounds which flows through it, this is believed to be the first time that di-hydrogen oxide, known to scientists by its chemical formula H20, has been detected since regular testing began in 1994.
A spokesman for the Shanghai Environmental Protection Bureau, who gave his surname as Jiang, said: "This is an isolated occurence. We have identified the source and taken the necessary mesasures. This substance poses no risk to the public, and people should go about their business as usual."
Asked how the substance - which is formed by a chemical reaction between hydrogen (an exlosive gas) and oxygen (which is toxic in high concentrations) - came to be found in the Huangpu, Mr Jiang said that it was not convenient to say. Another Bureau official, speaking on condition of anonymity, said that the chemical had probably leaked into the river from "another source", but he could not say what that source might have been.
Shanghai health department officials have stressed that there is little likelihood of the contamination finding its way into the city's drinking supply.
However, some local residents were taking no chances last night, saying that they would not trust what comes out of their kitchen taps until tests show that the leak has been completely cleared up.
Mr Guo, a pedestrian crossing assistant from the city's north-eastern Hongkou district, told reporters: "There's a rumour going round our neighbourhood that this di-hydrogen stuff is in fact what we Shanghainese have always called shui [a local word for 'water']. If that's the case, then of course we're worried. The last time we had shui in our taps was back in 1966, and it didn't do us a lot of good then, I can tell you. People went crazy as a result of drinking the stuff. Even high-ranking officials were affected.
Mr Guo, wearing sunglasses, white gloves, a yellow baseball cap, and a buff-coloured shirt, went on to say: "We're just praying that it's a false alarm this time. If it turns out to be true, I'm going to take my family down to stay with relatives in Guangzhou till they get this situation under control. I know for a fact that there is no shui contamination in the Zhu Jiang [Pearl River]."
Shares in Suntory Ltd, the Japanese drinks giant that owns Shanghai's largest brewery, fell almost 5% on the news.