As edie was published, the struggle was still ensuing to prevent the further spread of the leak from the comparatively remote area of Northwest China, where the spill occurred, to major tributaries and a reservoir supplying millions, including the political elite.

As yet, no human casualties have been reported, but wildlife is reported to be have been devastated along a 14km stretch downriver from the accident’s site at a branch of the Hanjiang in Shaanxi Province, which joins the Yangtze River, upon which a quarter of China’s total farmland and one-third of its 1.1 billion population depend. The area lies about 950km south-west of Beijing.

The leak of 5.2 tons of sodium cyanide occurred when a container truck plunged from the road into the river on 29 September, but no reports of the accident appeared in the Chinese press until 3 October.

According to Chinese media, emergency teams, including the army, were immediately dispatched to the site and built two dams to try to prevent the spread of the chemicals. Detergents were then released into the river to decompose and neutralise the chemicals.

Authorities in Shaanxi and Hubei provinces have warned people along the river not to use river water, imposed a ban on drinking tap water and distributed anti-poison medicines. But a six-kilometre toxic slick has already entered the Danjiangkou Reservoir, one of China’s biggest man-made lakes, which feeds the Huanshui River, a major tributary of the Yangtze, which runs through 11 provinces and cities, and also provides water for the Zhongnanhai compound in Beijing, where China’s leaders live. Chinese Premier Zhu Rongji called on local officials to take “urgent measures” to slow the slick.

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