Toxic sludge spill. Satellite image of toxic sludge (red, across centre) that spilt from an aluminium oxide plant in western Hungary on 4th October 2010. An estimated 700,000 cubic metres of caustic sludge were released after a corner wall of a retaining pond broke. The sludge swept into surrounding towns, reaching 2 metres in depth at places. Eight people died as a result of the spill and many others needed treatment for chemical burns. Heavy metals in the sludge could remain in the soil and food chain for decades. Image taken by the Advanced Land Imager (ALI) on NASA's Earth Observing-1 satellite on 9th October 2010.