KHABAROVSK, Dec 22: Toxic chemicals that contaminated a river after a blast at a factory in China last month flowed into the Russian city of Khabarovsk on Thursday, but officials said concentrations were low so far and posed a negligible risk to human health.

“We are taking measurements every three hours at many points,” said Valentina Zozulina, senior laboratory engineer with the Institute of Tectonics and Geophysics with the Russian Academy of Science, who confirmed that toxic nitrobenzene had been detected in waters in Khabarovsk.

She said however that the highest concentrations detected so far in the wider Khabarovsk region were well below acceptable limits and were substantially lower in the waters within the limits of the city itself, which is home to around 600,000 people.

Maximum toxic concentrations were expected to flow into the city from Friday and the entire slick, which has stretched to 190kms in length, will take up to four days to flow through Khabarovsk.

Scientists predicted however that even the highest concentrations would stay below maximum tolerance levels. Officials said new charcoal filters were capable of cleaning the river water and Khabarovsk city did not plan to shut off public water supplies.

The spill was caused by an explosion at a chemical factory in China on Nov 13 that resulted in 100 tons of benzene being dumped in the Songhua river, a tributary of the Amur which runs along the Russia-Chinese border.—AFP