Kolontar (Hungary): Workers raced to build an emergency dam in western Hungary on Sunday as cracks in a reservoir widened, threatening to unleash a second torrent of toxic sludge on the village of Kolontar and nearby rivers. About one million cubic metres of the waste material leaked out of the alumina plant reservoir into villages and waterways earlier this week, killing seven people, injuring 123 and fouling rivers including a local branch of the Danube. Kolontar was evacuated on Saturday after cracks appeared in the northern wall of the reservoir, threatening a second spill of the toxic red sludge, which swept through neighboring areas on Monday, toppling cars and wreaking havoc in houses. A by-product of alumina production, the thick, highly alkaline substance has a caustic effect on the skin. It contains heavy metals, such as lead, and is slightly radioactive. Inhaling its dust can cause lung cancer. Environment state secretary Zoltan Illes said a 25-meter-long crack in the weakened wall had widened slightly by Sunday morning and the wall of the damaged reservoir now looked beyond repair. Illes said the northern wall of the reservoir could collapse